Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 6687 insertions, 0 deletions

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
new file mode 100644
index 000000000..8a819d0a7
--- /dev/null
+++ b/net/core/skbuff.c
@@ -0,0 +1,6687 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *	Routines having to do with the 'struct sk_buff' memory handlers.
+ *
+ *	Authors:	Alan Cox <alan@lxorguk.ukuu.org.uk>
+ *			Florian La Roche <rzsfl@rz.uni-sb.de>
+ *
+ *	Fixes:
+ *		Alan Cox	:	Fixed the worst of the load
+ *					balancer bugs.
+ *		Dave Platt	:	Interrupt stacking fix.
+ *	Richard Kooijman	:	Timestamp fixes.
+ *		Alan Cox	:	Changed buffer format.
+ *		Alan Cox	:	destructor hook for AF_UNIX etc.
+ *		Linus Torvalds	:	Better skb_clone.
+ *		Alan Cox	:	Added skb_copy.
+ *		Alan Cox	:	Added all the changed routines Linus
+ *					only put in the headers
+ *		Ray VanTassle	:	Fixed --skb->lock in free
+ *		Alan Cox	:	skb_copy copy arp field
+ *		Andi Kleen	:	slabified it.
+ *		Robert Olsson	:	Removed skb_head_pool
+ *
+ *	NOTE:
+ *		The __skb_ routines should be called with interrupts
+ *	disabled, or you better be *real* sure that the operation is atomic
+ *	with respect to whatever list is being frobbed (e.g. via lock_sock()
+ *	or via disabling bottom half handlers, etc).
+ */
+
+/*
+ *	The functions in this file will not compile correctly with gcc 2.4.x
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <linux/in.h>
+#include <linux/inet.h>
+#include <linux/slab.h>
+#include <linux/tcp.h>
+#include <linux/udp.h>
+#include <linux/sctp.h>
+#include <linux/netdevice.h>
+#ifdef CONFIG_NET_CLS_ACT
+#include <net/pkt_sched.h>
+#endif
+#include <linux/string.h>
+#include <linux/skbuff.h>
+#include <linux/splice.h>
+#include <linux/cache.h>
+#include <linux/rtnetlink.h>
+#include <linux/init.h>
+#include <linux/scatterlist.h>
+#include <linux/errqueue.h>
+#include <linux/prefetch.h>
+#include <linux/if_vlan.h>
+#include <linux/mpls.h>
+#include <linux/kcov.h>
+
+#include <net/protocol.h>
+#include <net/dst.h>
+#include <net/sock.h>
+#include <net/checksum.h>
+#include <net/ip6_checksum.h>
+#include <net/xfrm.h>
+#include <net/mpls.h>
+#include <net/mptcp.h>
+#include <net/mctp.h>
+#include <net/page_pool.h>
+
+#include <linux/uaccess.h>
+#include <trace/events/skb.h>
+#include <linux/highmem.h>
+#include <linux/capability.h>
+#include <linux/user_namespace.h>
+#include <linux/indirect_call_wrapper.h>
+
+#include "dev.h"
+#include "sock_destructor.h"
+
+struct kmem_cache *skbuff_head_cache __ro_after_init;
+static struct kmem_cache *skbuff_fclone_cache __ro_after_init;
+#ifdef CONFIG_SKB_EXTENSIONS
+static struct kmem_cache *skbuff_ext_cache __ro_after_init;
+#endif
+int sysctl_max_skb_frags __read_mostly = MAX_SKB_FRAGS;
+EXPORT_SYMBOL(sysctl_max_skb_frags);
+
+#undef FN
+#define FN(reason) [SKB_DROP_REASON_##reason] = #reason,
+const char * const drop_reasons[] = {
+	DEFINE_DROP_REASON(FN, FN)
+};
+EXPORT_SYMBOL(drop_reasons);
+
+/**
+ *	skb_panic - private function for out-of-line support
+ *	@skb:	buffer
+ *	@sz:	size
+ *	@addr:	address
+ *	@msg:	skb_over_panic or skb_under_panic
+ *
+ *	Out-of-line support for skb_put() and skb_push().
+ *	Called via the wrapper skb_over_panic() or skb_under_panic().
+ *	Keep out of line to prevent kernel bloat.
+ *	__builtin_return_address is not used because it is not always reliable.
+ */
+static void skb_panic(struct sk_buff *skb, unsigned int sz, void *addr,
+		      const char msg[])
+{
+	pr_emerg("%s: text:%px len:%d put:%d head:%px data:%px tail:%#lx end:%#lx dev:%s\n",
+		 msg, addr, skb->len, sz, skb->head, skb->data,
+		 (unsigned long)skb->tail, (unsigned long)skb->end,
+		 skb->dev ? skb->dev->name : "<NULL>");
+	BUG();
+}
+
+static void skb_over_panic(struct sk_buff *skb, unsigned int sz, void *addr)
+{
+	skb_panic(skb, sz, addr, __func__);
+}
+
+static void skb_under_panic(struct sk_buff *skb, unsigned int sz, void *addr)
+{
+	skb_panic(skb, sz, addr, __func__);
+}
+
+#define NAPI_SKB_CACHE_SIZE	64
+#define NAPI_SKB_CACHE_BULK	16
+#define NAPI_SKB_CACHE_HALF	(NAPI_SKB_CACHE_SIZE / 2)
+
+#if PAGE_SIZE == SZ_4K
+
+#define NAPI_HAS_SMALL_PAGE_FRAG	1
+#define NAPI_SMALL_PAGE_PFMEMALLOC(nc)	((nc).pfmemalloc)
+
+/* specialized page frag allocator using a single order 0 page
+ * and slicing it into 1K sized fragment. Constrained to systems
+ * with a very limited amount of 1K fragments fitting a single
+ * page - to avoid excessive truesize underestimation
+ */
+
+struct page_frag_1k {
+	void *va;
+	u16 offset;
+	bool pfmemalloc;
+};
+
+static void *page_frag_alloc_1k(struct page_frag_1k *nc, gfp_t gfp)
+{
+	struct page *page;
+	int offset;
+
+	offset = nc->offset - SZ_1K;
+	if (likely(offset >= 0))
+		goto use_frag;
+
+	page = alloc_pages_node(NUMA_NO_NODE, gfp, 0);
+	if (!page)
+		return NULL;
+
+	nc->va = page_address(page);
+	nc->pfmemalloc = page_is_pfmemalloc(page);
+	offset = PAGE_SIZE - SZ_1K;
+	page_ref_add(page, offset / SZ_1K);
+
+use_frag:
+	nc->offset = offset;
+	return nc->va + offset;
+}
+#else
+
+/* the small page is actually unused in this build; add dummy helpers
+ * to please the compiler and avoid later preprocessor's conditionals
+ */
+#define NAPI_HAS_SMALL_PAGE_FRAG	0
+#define NAPI_SMALL_PAGE_PFMEMALLOC(nc)	false
+
+struct page_frag_1k {
+};
+
+static void *page_frag_alloc_1k(struct page_frag_1k *nc, gfp_t gfp_mask)
+{
+	return NULL;
+}
+
+#endif
+
+struct napi_alloc_cache {
+	struct page_frag_cache page;
+	struct page_frag_1k page_small;
+	unsigned int skb_count;
+	void *skb_cache[NAPI_SKB_CACHE_SIZE];
+};
+
+static DEFINE_PER_CPU(struct page_frag_cache, netdev_alloc_cache);
+static DEFINE_PER_CPU(struct napi_alloc_cache, napi_alloc_cache);
+
+/* Double check that napi_get_frags() allocates skbs with
+ * skb->head being backed by slab, not a page fragment.
+ * This is to make sure bug fixed in 3226b158e67c
+ * ("net: avoid 32 x truesize under-estimation for tiny skbs")
+ * does not accidentally come back.
+ */
+void napi_get_frags_check(struct napi_struct *napi)
+{
+	struct sk_buff *skb;
+
+	local_bh_disable();
+	skb = napi_get_frags(napi);
+	WARN_ON_ONCE(!NAPI_HAS_SMALL_PAGE_FRAG && skb && skb->head_frag);
+	napi_free_frags(napi);
+	local_bh_enable();
+}
+
+void *__napi_alloc_frag_align(unsigned int fragsz, unsigned int align_mask)
+{
+	struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
+
+	fragsz = SKB_DATA_ALIGN(fragsz);
+
+	return page_frag_alloc_align(&nc->page, fragsz, GFP_ATOMIC, align_mask);
+}
+EXPORT_SYMBOL(__napi_alloc_frag_align);
+
+void *__netdev_alloc_frag_align(unsigned int fragsz, unsigned int align_mask)
+{
+	void *data;
+
+	fragsz = SKB_DATA_ALIGN(fragsz);
+	if (in_hardirq() || irqs_disabled()) {
+		struct page_frag_cache *nc = this_cpu_ptr(&netdev_alloc_cache);
+
+		data = page_frag_alloc_align(nc, fragsz, GFP_ATOMIC, align_mask);
+	} else {
+		struct napi_alloc_cache *nc;
+
+		local_bh_disable();
+		nc = this_cpu_ptr(&napi_alloc_cache);
+		data = page_frag_alloc_align(&nc->page, fragsz, GFP_ATOMIC, align_mask);
+		local_bh_enable();
+	}
+	return data;
+}
+EXPORT_SYMBOL(__netdev_alloc_frag_align);
+
+static struct sk_buff *napi_skb_cache_get(void)
+{
+	struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
+	struct sk_buff *skb;
+
+	if (unlikely(!nc->skb_count)) {
+		nc->skb_count = kmem_cache_alloc_bulk(skbuff_head_cache,
+						      GFP_ATOMIC,
+						      NAPI_SKB_CACHE_BULK,
+						      nc->skb_cache);
+		if (unlikely(!nc->skb_count))
+			return NULL;
+	}
+
+	skb = nc->skb_cache[--nc->skb_count];
+	kasan_unpoison_object_data(skbuff_head_cache, skb);
+
+	return skb;
+}
+
+/* Caller must provide SKB that is memset cleared */
+static void __build_skb_around(struct sk_buff *skb, void *data,
+			       unsigned int frag_size)
+{
+	struct skb_shared_info *shinfo;
+	unsigned int size = frag_size ? : ksize(data);
+
+	size -= SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
+
+	/* Assumes caller memset cleared SKB */
+	skb->truesize = SKB_TRUESIZE(size);
+	refcount_set(&skb->users, 1);
+	skb->head = data;
+	skb->data = data;
+	skb_reset_tail_pointer(skb);
+	skb_set_end_offset(skb, size);
+	skb->mac_header = (typeof(skb->mac_header))~0U;
+	skb->transport_header = (typeof(skb->transport_header))~0U;
+	skb->alloc_cpu = raw_smp_processor_id();
+	/* make sure we initialize shinfo sequentially */
+	shinfo = skb_shinfo(skb);
+	memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
+	atomic_set(&shinfo->dataref, 1);
+
+	skb_set_kcov_handle(skb, kcov_common_handle());
+}
+
+/**
+ * __build_skb - build a network buffer
+ * @data: data buffer provided by caller
+ * @frag_size: size of data, or 0 if head was kmalloced
+ *
+ * Allocate a new &sk_buff. Caller provides space holding head and
+ * skb_shared_info. @data must have been allocated by kmalloc() only if
+ * @frag_size is 0, otherwise data should come from the page allocator
+ *  or vmalloc()
+ * The return is the new skb buffer.
+ * On a failure the return is %NULL, and @data is not freed.
+ * Notes :
+ *  Before IO, driver allocates only data buffer where NIC put incoming frame
+ *  Driver should add room at head (NET_SKB_PAD) and
+ *  MUST add room at tail (SKB_DATA_ALIGN(skb_shared_info))
+ *  After IO, driver calls build_skb(), to allocate sk_buff and populate it
+ *  before giving packet to stack.
+ *  RX rings only contains data buffers, not full skbs.
+ */
+struct sk_buff *__build_skb(void *data, unsigned int frag_size)
+{
+	struct sk_buff *skb;
+
+	skb = kmem_cache_alloc(skbuff_head_cache, GFP_ATOMIC);
+	if (unlikely(!skb))
+		return NULL;
+
+	memset(skb, 0, offsetof(struct sk_buff, tail));
+	__build_skb_around(skb, data, frag_size);
+
+	return skb;
+}
+
+/* build_skb() is wrapper over __build_skb(), that specifically
+ * takes care of skb->head and skb->pfmemalloc
+ * This means that if @frag_size is not zero, then @data must be backed
+ * by a page fragment, not kmalloc() or vmalloc()
+ */
+struct sk_buff *build_skb(void *data, unsigned int frag_size)
+{
+	struct sk_buff *skb = __build_skb(data, frag_size);
+
+	if (skb && frag_size) {
+		skb->head_frag = 1;
+		if (page_is_pfmemalloc(virt_to_head_page(data)))
+			skb->pfmemalloc = 1;
+	}
+	return skb;
+}
+EXPORT_SYMBOL(build_skb);
+
+/**
+ * build_skb_around - build a network buffer around provided skb
+ * @skb: sk_buff provide by caller, must be memset cleared
+ * @data: data buffer provided by caller
+ * @frag_size: size of data, or 0 if head was kmalloced
+ */
+struct sk_buff *build_skb_around(struct sk_buff *skb,
+				 void *data, unsigned int frag_size)
+{
+	if (unlikely(!skb))
+		return NULL;
+
+	__build_skb_around(skb, data, frag_size);
+
+	if (frag_size) {
+		skb->head_frag = 1;
+		if (page_is_pfmemalloc(virt_to_head_page(data)))
+			skb->pfmemalloc = 1;
+	}
+	return skb;
+}
+EXPORT_SYMBOL(build_skb_around);
+
+/**
+ * __napi_build_skb - build a network buffer
+ * @data: data buffer provided by caller
+ * @frag_size: size of data, or 0 if head was kmalloced
+ *
+ * Version of __build_skb() that uses NAPI percpu caches to obtain
+ * skbuff_head instead of inplace allocation.
+ *
+ * Returns a new &sk_buff on success, %NULL on allocation failure.
+ */
+static struct sk_buff *__napi_build_skb(void *data, unsigned int frag_size)
+{
+	struct sk_buff *skb;
+
+	skb = napi_skb_cache_get();
+	if (unlikely(!skb))
+		return NULL;
+
+	memset(skb, 0, offsetof(struct sk_buff, tail));
+	__build_skb_around(skb, data, frag_size);
+
+	return skb;
+}
+
+/**
+ * napi_build_skb - build a network buffer
+ * @data: data buffer provided by caller
+ * @frag_size: size of data, or 0 if head was kmalloced
+ *
+ * Version of __napi_build_skb() that takes care of skb->head_frag
+ * and skb->pfmemalloc when the data is a page or page fragment.
+ *
+ * Returns a new &sk_buff on success, %NULL on allocation failure.
+ */
+struct sk_buff *napi_build_skb(void *data, unsigned int frag_size)
+{
+	struct sk_buff *skb = __napi_build_skb(data, frag_size);
+
+	if (likely(skb) && frag_size) {
+		skb->head_frag = 1;
+		skb_propagate_pfmemalloc(virt_to_head_page(data), skb);
+	}
+
+	return skb;
+}
+EXPORT_SYMBOL(napi_build_skb);
+
+/*
+ * kmalloc_reserve is a wrapper around kmalloc_node_track_caller that tells
+ * the caller if emergency pfmemalloc reserves are being used. If it is and
+ * the socket is later found to be SOCK_MEMALLOC then PFMEMALLOC reserves
+ * may be used. Otherwise, the packet data may be discarded until enough
+ * memory is free
+ */
+static void *kmalloc_reserve(unsigned int *size, gfp_t flags, int node,
+			     bool *pfmemalloc)
+{
+	bool ret_pfmemalloc = false;
+	size_t obj_size;
+	void *obj;
+
+	obj_size = SKB_HEAD_ALIGN(*size);
+
+	obj_size = kmalloc_size_roundup(obj_size);
+	/* The following cast might truncate high-order bits of obj_size, this
+	 * is harmless because kmalloc(obj_size >= 2^32) will fail anyway.
+	 */
+	*size = (unsigned int)obj_size;
+
+	/*
+	 * Try a regular allocation, when that fails and we're not entitled
+	 * to the reserves, fail.
+	 */
+	obj = kmalloc_node_track_caller(obj_size,
+					flags | __GFP_NOMEMALLOC | __GFP_NOWARN,
+					node);
+	if (obj || !(gfp_pfmemalloc_allowed(flags)))
+		goto out;
+
+	/* Try again but now we are using pfmemalloc reserves */
+	ret_pfmemalloc = true;
+	obj = kmalloc_node_track_caller(obj_size, flags, node);
+
+out:
+	if (pfmemalloc)
+		*pfmemalloc = ret_pfmemalloc;
+
+	return obj;
+}
+
+/* 	Allocate a new skbuff. We do this ourselves so we can fill in a few
+ *	'private' fields and also do memory statistics to find all the
+ *	[BEEP] leaks.
+ *
+ */
+
+/**
+ *	__alloc_skb	-	allocate a network buffer
+ *	@size: size to allocate
+ *	@gfp_mask: allocation mask
+ *	@flags: If SKB_ALLOC_FCLONE is set, allocate from fclone cache
+ *		instead of head cache and allocate a cloned (child) skb.
+ *		If SKB_ALLOC_RX is set, __GFP_MEMALLOC will be used for
+ *		allocations in case the data is required for writeback
+ *	@node: numa node to allocate memory on
+ *
+ *	Allocate a new &sk_buff. The returned buffer has no headroom and a
+ *	tail room of at least size bytes. The object has a reference count
+ *	of one. The return is the buffer. On a failure the return is %NULL.
+ *
+ *	Buffers may only be allocated from interrupts using a @gfp_mask of
+ *	%GFP_ATOMIC.
+ */
+struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
+			    int flags, int node)
+{
+	struct kmem_cache *cache;
+	struct sk_buff *skb;
+	bool pfmemalloc;
+	u8 *data;
+
+	cache = (flags & SKB_ALLOC_FCLONE)
+		? skbuff_fclone_cache : skbuff_head_cache;
+
+	if (sk_memalloc_socks() && (flags & SKB_ALLOC_RX))
+		gfp_mask |= __GFP_MEMALLOC;
+
+	/* Get the HEAD */
+	if ((flags & (SKB_ALLOC_FCLONE | SKB_ALLOC_NAPI)) == SKB_ALLOC_NAPI &&
+	    likely(node == NUMA_NO_NODE || node == numa_mem_id()))
+		skb = napi_skb_cache_get();
+	else
+		skb = kmem_cache_alloc_node(cache, gfp_mask & ~GFP_DMA, node);
+	if (unlikely(!skb))
+		return NULL;
+	prefetchw(skb);
+
+	/* We do our best to align skb_shared_info on a separate cache
+	 * line. It usually works because kmalloc(X > SMP_CACHE_BYTES) gives
+	 * aligned memory blocks, unless SLUB/SLAB debug is enabled.
+	 * Both skb->head and skb_shared_info are cache line aligned.
+	 */
+	data = kmalloc_reserve(&size, gfp_mask, node, &pfmemalloc);
+	if (unlikely(!data))
+		goto nodata;
+	/* kmalloc_size_roundup() might give us more room than requested.
+	 * Put skb_shared_info exactly at the end of allocated zone,
+	 * to allow max possible filling before reallocation.
+	 */
+	prefetchw(data + SKB_WITH_OVERHEAD(size));
+
+	/*
+	 * Only clear those fields we need to clear, not those that we will
+	 * actually initialise below. Hence, don't put any more fields after
+	 * the tail pointer in struct sk_buff!
+	 */
+	memset(skb, 0, offsetof(struct sk_buff, tail));
+	__build_skb_around(skb, data, size);
+	skb->pfmemalloc = pfmemalloc;
+
+	if (flags & SKB_ALLOC_FCLONE) {
+		struct sk_buff_fclones *fclones;
+
+		fclones = container_of(skb, struct sk_buff_fclones, skb1);
+
+		skb->fclone = SKB_FCLONE_ORIG;
+		refcount_set(&fclones->fclone_ref, 1);
+	}
+
+	return skb;
+
+nodata:
+	kmem_cache_free(cache, skb);
+	return NULL;
+}
+EXPORT_SYMBOL(__alloc_skb);
+
+/**
+ *	__netdev_alloc_skb - allocate an skbuff for rx on a specific device
+ *	@dev: network device to receive on
+ *	@len: length to allocate
+ *	@gfp_mask: get_free_pages mask, passed to alloc_skb
+ *
+ *	Allocate a new &sk_buff and assign it a usage count of one. The
+ *	buffer has NET_SKB_PAD headroom built in. Users should allocate
+ *	the headroom they think they need without accounting for the
+ *	built in space. The built in space is used for optimisations.
+ *
+ *	%NULL is returned if there is no free memory.
+ */
+struct sk_buff *__netdev_alloc_skb(struct net_device *dev, unsigned int len,
+				   gfp_t gfp_mask)
+{
+	struct page_frag_cache *nc;
+	struct sk_buff *skb;
+	bool pfmemalloc;
+	void *data;
+
+	len += NET_SKB_PAD;
+
+	/* If requested length is either too small or too big,
+	 * we use kmalloc() for skb->head allocation.
+	 */
+	if (len <= SKB_WITH_OVERHEAD(1024) ||
+	    len > SKB_WITH_OVERHEAD(PAGE_SIZE) ||
+	    (gfp_mask & (__GFP_DIRECT_RECLAIM | GFP_DMA))) {
+		skb = __alloc_skb(len, gfp_mask, SKB_ALLOC_RX, NUMA_NO_NODE);
+		if (!skb)
+			goto skb_fail;
+		goto skb_success;
+	}
+
+	len = SKB_HEAD_ALIGN(len);
+
+	if (sk_memalloc_socks())
+		gfp_mask |= __GFP_MEMALLOC;
+
+	if (in_hardirq() || irqs_disabled()) {
+		nc = this_cpu_ptr(&netdev_alloc_cache);
+		data = page_frag_alloc(nc, len, gfp_mask);
+		pfmemalloc = nc->pfmemalloc;
+	} else {
+		local_bh_disable();
+		nc = this_cpu_ptr(&napi_alloc_cache.page);
+		data = page_frag_alloc(nc, len, gfp_mask);
+		pfmemalloc = nc->pfmemalloc;
+		local_bh_enable();
+	}
+
+	if (unlikely(!data))
+		return NULL;
+
+	skb = __build_skb(data, len);
+	if (unlikely(!skb)) {
+		skb_free_frag(data);
+		return NULL;
+	}
+
+	if (pfmemalloc)
+		skb->pfmemalloc = 1;
+	skb->head_frag = 1;
+
+skb_success:
+	skb_reserve(skb, NET_SKB_PAD);
+	skb->dev = dev;
+
+skb_fail:
+	return skb;
+}
+EXPORT_SYMBOL(__netdev_alloc_skb);
+
+/**
+ *	__napi_alloc_skb - allocate skbuff for rx in a specific NAPI instance
+ *	@napi: napi instance this buffer was allocated for
+ *	@len: length to allocate
+ *	@gfp_mask: get_free_pages mask, passed to alloc_skb and alloc_pages
+ *
+ *	Allocate a new sk_buff for use in NAPI receive.  This buffer will
+ *	attempt to allocate the head from a special reserved region used
+ *	only for NAPI Rx allocation.  By doing this we can save several
+ *	CPU cycles by avoiding having to disable and re-enable IRQs.
+ *
+ *	%NULL is returned if there is no free memory.
+ */
+struct sk_buff *__napi_alloc_skb(struct napi_struct *napi, unsigned int len,
+				 gfp_t gfp_mask)
+{
+	struct napi_alloc_cache *nc;
+	struct sk_buff *skb;
+	bool pfmemalloc;
+	void *data;
+
+	DEBUG_NET_WARN_ON_ONCE(!in_softirq());
+	len += NET_SKB_PAD + NET_IP_ALIGN;
+
+	/* If requested length is either too small or too big,
+	 * we use kmalloc() for skb->head allocation.
+	 * When the small frag allocator is available, prefer it over kmalloc
+	 * for small fragments
+	 */
+	if ((!NAPI_HAS_SMALL_PAGE_FRAG && len <= SKB_WITH_OVERHEAD(1024)) ||
+	    len > SKB_WITH_OVERHEAD(PAGE_SIZE) ||
+	    (gfp_mask & (__GFP_DIRECT_RECLAIM | GFP_DMA))) {
+		skb = __alloc_skb(len, gfp_mask, SKB_ALLOC_RX | SKB_ALLOC_NAPI,
+				  NUMA_NO_NODE);
+		if (!skb)
+			goto skb_fail;
+		goto skb_success;
+	}
+
+	nc = this_cpu_ptr(&napi_alloc_cache);
+
+	if (sk_memalloc_socks())
+		gfp_mask |= __GFP_MEMALLOC;
+
+	if (NAPI_HAS_SMALL_PAGE_FRAG && len <= SKB_WITH_OVERHEAD(1024)) {
+		/* we are artificially inflating the allocation size, but
+		 * that is not as bad as it may look like, as:
+		 * - 'len' less than GRO_MAX_HEAD makes little sense
+		 * - On most systems, larger 'len' values lead to fragment
+		 *   size above 512 bytes
+		 * - kmalloc would use the kmalloc-1k slab for such values
+		 * - Builds with smaller GRO_MAX_HEAD will very likely do
+		 *   little networking, as that implies no WiFi and no
+		 *   tunnels support, and 32 bits arches.
+		 */
+		len = SZ_1K;
+
+		data = page_frag_alloc_1k(&nc->page_small, gfp_mask);
+		pfmemalloc = NAPI_SMALL_PAGE_PFMEMALLOC(nc->page_small);
+	} else {
+		len = SKB_HEAD_ALIGN(len);
+
+		data = page_frag_alloc(&nc->page, len, gfp_mask);
+		pfmemalloc = nc->page.pfmemalloc;
+	}
+
+	if (unlikely(!data))
+		return NULL;
+
+	skb = __napi_build_skb(data, len);
+	if (unlikely(!skb)) {
+		skb_free_frag(data);
+		return NULL;
+	}
+
+	if (pfmemalloc)
+		skb->pfmemalloc = 1;
+	skb->head_frag = 1;
+
+skb_success:
+	skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
+	skb->dev = napi->dev;
+
+skb_fail:
+	return skb;
+}
+EXPORT_SYMBOL(__napi_alloc_skb);
+
+void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
+		     int size, unsigned int truesize)
+{
+	skb_fill_page_desc(skb, i, page, off, size);
+	skb->len += size;
+	skb->data_len += size;
+	skb->truesize += truesize;
+}
+EXPORT_SYMBOL(skb_add_rx_frag);
+
+void skb_coalesce_rx_frag(struct sk_buff *skb, int i, int size,
+			  unsigned int truesize)
+{
+	skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
+
+	skb_frag_size_add(frag, size);
+	skb->len += size;
+	skb->data_len += size;
+	skb->truesize += truesize;
+}
+EXPORT_SYMBOL(skb_coalesce_rx_frag);
+
+static void skb_drop_list(struct sk_buff **listp)
+{
+	kfree_skb_list(*listp);
+	*listp = NULL;
+}
+
+static inline void skb_drop_fraglist(struct sk_buff *skb)
+{
+	skb_drop_list(&skb_shinfo(skb)->frag_list);
+}
+
+static void skb_clone_fraglist(struct sk_buff *skb)
+{
+	struct sk_buff *list;
+
+	skb_walk_frags(skb, list)
+		skb_get(list);
+}
+
+static void skb_free_head(struct sk_buff *skb)
+{
+	unsigned char *head = skb->head;
+
+	if (skb->head_frag) {
+		if (skb_pp_recycle(skb, head))
+			return;
+		skb_free_frag(head);
+	} else {
+		kfree(head);
+	}
+}
+
+static void skb_release_data(struct sk_buff *skb)
+{
+	struct skb_shared_info *shinfo = skb_shinfo(skb);
+	int i;
+
+	if (skb->cloned &&
+	    atomic_sub_return(skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1,
+			      &shinfo->dataref))
+		goto exit;
+
+	if (skb_zcopy(skb)) {
+		bool skip_unref = shinfo->flags & SKBFL_MANAGED_FRAG_REFS;
+
+		skb_zcopy_clear(skb, true);
+		if (skip_unref)
+			goto free_head;
+	}
+
+	for (i = 0; i < shinfo->nr_frags; i++)
+		__skb_frag_unref(&shinfo->frags[i], skb->pp_recycle);
+
+free_head:
+	if (shinfo->frag_list)
+		kfree_skb_list(shinfo->frag_list);
+
+	skb_free_head(skb);
+exit:
+	/* When we clone an SKB we copy the reycling bit. The pp_recycle
+	 * bit is only set on the head though, so in order to avoid races
+	 * while trying to recycle fragments on __skb_frag_unref() we need
+	 * to make one SKB responsible for triggering the recycle path.
+	 * So disable the recycling bit if an SKB is cloned and we have
+	 * additional references to the fragmented part of the SKB.
+	 * Eventually the last SKB will have the recycling bit set and it's
+	 * dataref set to 0, which will trigger the recycling
+	 */
+	skb->pp_recycle = 0;
+}
+
+/*
+ *	Free an skbuff by memory without cleaning the state.
+ */
+static void kfree_skbmem(struct sk_buff *skb)
+{
+	struct sk_buff_fclones *fclones;
+
+	switch (skb->fclone) {
+	case SKB_FCLONE_UNAVAILABLE:
+		kmem_cache_free(skbuff_head_cache, skb);
+		return;
+
+	case SKB_FCLONE_ORIG:
+		fclones = container_of(skb, struct sk_buff_fclones, skb1);
+
+		/* We usually free the clone (TX completion) before original skb
+		 * This test would have no chance to be true for the clone,
+		 * while here, branch prediction will be good.
+		 */
+		if (refcount_read(&fclones->fclone_ref) == 1)
+			goto fastpath;
+		break;
+
+	default: /* SKB_FCLONE_CLONE */
+		fclones = container_of(skb, struct sk_buff_fclones, skb2);
+		break;
+	}
+	if (!refcount_dec_and_test(&fclones->fclone_ref))
+		return;
+fastpath:
+	kmem_cache_free(skbuff_fclone_cache, fclones);
+}
+
+void skb_release_head_state(struct sk_buff *skb)
+{
+	skb_dst_drop(skb);
+	if (skb->destructor) {
+		DEBUG_NET_WARN_ON_ONCE(in_hardirq());
+		skb->destructor(skb);
+	}
+#if IS_ENABLED(CONFIG_NF_CONNTRACK)
+	nf_conntrack_put(skb_nfct(skb));
+#endif
+	skb_ext_put(skb);
+}
+
+/* Free everything but the sk_buff shell. */
+static void skb_release_all(struct sk_buff *skb)
+{
+	skb_release_head_state(skb);
+	if (likely(skb->head))
+		skb_release_data(skb);
+}
+
+/**
+ *	__kfree_skb - private function
+ *	@skb: buffer
+ *
+ *	Free an sk_buff. Release anything attached to the buffer.
+ *	Clean the state. This is an internal helper function. Users should
+ *	always call kfree_skb
+ */
+
+void __kfree_skb(struct sk_buff *skb)
+{
+	skb_release_all(skb);
+	kfree_skbmem(skb);
+}
+EXPORT_SYMBOL(__kfree_skb);
+
+/**
+ *	kfree_skb_reason - free an sk_buff with special reason
+ *	@skb: buffer to free
+ *	@reason: reason why this skb is dropped
+ *
+ *	Drop a reference to the buffer and free it if the usage count has
+ *	hit zero. Meanwhile, pass the drop reason to 'kfree_skb'
+ *	tracepoint.
+ */
+void __fix_address
+kfree_skb_reason(struct sk_buff *skb, enum skb_drop_reason reason)
+{
+	if (unlikely(!skb_unref(skb)))
+		return;
+
+	DEBUG_NET_WARN_ON_ONCE(reason <= 0 || reason >= SKB_DROP_REASON_MAX);
+
+	trace_kfree_skb(skb, __builtin_return_address(0), reason);
+	__kfree_skb(skb);
+}
+EXPORT_SYMBOL(kfree_skb_reason);
+
+void kfree_skb_list_reason(struct sk_buff *segs,
+			   enum skb_drop_reason reason)
+{
+	while (segs) {
+		struct sk_buff *next = segs->next;
+
+		kfree_skb_reason(segs, reason);
+		segs = next;
+	}
+}
+EXPORT_SYMBOL(kfree_skb_list_reason);
+
+/* Dump skb information and contents.
+ *
+ * Must only be called from net_ratelimit()-ed paths.
+ *
+ * Dumps whole packets if full_pkt, only headers otherwise.
+ */
+void skb_dump(const char *level, const struct sk_buff *skb, bool full_pkt)
+{
+	struct skb_shared_info *sh = skb_shinfo(skb);
+	struct net_device *dev = skb->dev;
+	struct sock *sk = skb->sk;
+	struct sk_buff *list_skb;
+	bool has_mac, has_trans;
+	int headroom, tailroom;
+	int i, len, seg_len;
+
+	if (full_pkt)
+		len = skb->len;
+	else
+		len = min_t(int, skb->len, MAX_HEADER + 128);
+
+	headroom = skb_headroom(skb);
+	tailroom = skb_tailroom(skb);
+
+	has_mac = skb_mac_header_was_set(skb);
+	has_trans = skb_transport_header_was_set(skb);
+
+	printk("%sskb len=%u headroom=%u headlen=%u tailroom=%u\n"
+	       "mac=(%d,%d) net=(%d,%d) trans=%d\n"
+	       "shinfo(txflags=%u nr_frags=%u gso(size=%hu type=%u segs=%hu))\n"
+	       "csum(0x%x ip_summed=%u complete_sw=%u valid=%u level=%u)\n"
+	       "hash(0x%x sw=%u l4=%u) proto=0x%04x pkttype=%u iif=%d\n",
+	       level, skb->len, headroom, skb_headlen(skb), tailroom,
+	       has_mac ? skb->mac_header : -1,
+	       has_mac ? skb_mac_header_len(skb) : -1,
+	       skb->network_header,
+	       has_trans ? skb_network_header_len(skb) : -1,
+	       has_trans ? skb->transport_header : -1,
+	       sh->tx_flags, sh->nr_frags,
+	       sh->gso_size, sh->gso_type, sh->gso_segs,
+	       skb->csum, skb->ip_summed, skb->csum_complete_sw,
+	       skb->csum_valid, skb->csum_level,
+	       skb->hash, skb->sw_hash, skb->l4_hash,
+	       ntohs(skb->protocol), skb->pkt_type, skb->skb_iif);
+
+	if (dev)
+		printk("%sdev name=%s feat=%pNF\n",
+		       level, dev->name, &dev->features);
+	if (sk)
+		printk("%ssk family=%hu type=%u proto=%u\n",
+		       level, sk->sk_family, sk->sk_type, sk->sk_protocol);
+
+	if (full_pkt && headroom)
+		print_hex_dump(level, "skb headroom: ", DUMP_PREFIX_OFFSET,
+			       16, 1, skb->head, headroom, false);
+
+	seg_len = min_t(int, skb_headlen(skb), len);
+	if (seg_len)
+		print_hex_dump(level, "skb linear:   ", DUMP_PREFIX_OFFSET,
+			       16, 1, skb->data, seg_len, false);
+	len -= seg_len;
+
+	if (full_pkt && tailroom)
+		print_hex_dump(level, "skb tailroom: ", DUMP_PREFIX_OFFSET,
+			       16, 1, skb_tail_pointer(skb), tailroom, false);
+
+	for (i = 0; len && i < skb_shinfo(skb)->nr_frags; i++) {
+		skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
+		u32 p_off, p_len, copied;
+		struct page *p;
+		u8 *vaddr;
+
+		skb_frag_foreach_page(frag, skb_frag_off(frag),
+				      skb_frag_size(frag), p, p_off, p_len,
+				      copied) {
+			seg_len = min_t(int, p_len, len);
+			vaddr = kmap_atomic(p);
+			print_hex_dump(level, "skb frag:     ",
+				       DUMP_PREFIX_OFFSET,
+				       16, 1, vaddr + p_off, seg_len, false);
+			kunmap_atomic(vaddr);
+			len -= seg_len;
+			if (!len)
+				break;
+		}
+	}
+
+	if (full_pkt && skb_has_frag_list(skb)) {
+		printk("skb fraglist:\n");
+		skb_walk_frags(skb, list_skb)
+			skb_dump(level, list_skb, true);
+	}
+}
+EXPORT_SYMBOL(skb_dump);
+
+/**
+ *	skb_tx_error - report an sk_buff xmit error
+ *	@skb: buffer that triggered an error
+ *
+ *	Report xmit error if a device callback is tracking this skb.
+ *	skb must be freed afterwards.
+ */
+void skb_tx_error(struct sk_buff *skb)
+{
+	if (skb) {
+		skb_zcopy_downgrade_managed(skb);
+		skb_zcopy_clear(skb, true);
+	}
+}
+EXPORT_SYMBOL(skb_tx_error);
+
+#ifdef CONFIG_TRACEPOINTS
+/**
+ *	consume_skb - free an skbuff
+ *	@skb: buffer to free
+ *
+ *	Drop a ref to the buffer and free it if the usage count has hit zero
+ *	Functions identically to kfree_skb, but kfree_skb assumes that the frame
+ *	is being dropped after a failure and notes that
+ */
+void consume_skb(struct sk_buff *skb)
+{
+	if (!skb_unref(skb))
+		return;
+
+	trace_consume_skb(skb);
+	__kfree_skb(skb);
+}
+EXPORT_SYMBOL(consume_skb);
+#endif
+
+/**
+ *	__consume_stateless_skb - free an skbuff, assuming it is stateless
+ *	@skb: buffer to free
+ *
+ *	Alike consume_skb(), but this variant assumes that this is the last
+ *	skb reference and all the head states have been already dropped
+ */
+void __consume_stateless_skb(struct sk_buff *skb)
+{
+	trace_consume_skb(skb);
+	skb_release_data(skb);
+	kfree_skbmem(skb);
+}
+
+static void napi_skb_cache_put(struct sk_buff *skb)
+{
+	struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
+	u32 i;
+
+	kasan_poison_object_data(skbuff_head_cache, skb);
+	nc->skb_cache[nc->skb_count++] = skb;
+
+	if (unlikely(nc->skb_count == NAPI_SKB_CACHE_SIZE)) {
+		for (i = NAPI_SKB_CACHE_HALF; i < NAPI_SKB_CACHE_SIZE; i++)
+			kasan_unpoison_object_data(skbuff_head_cache,
+						   nc->skb_cache[i]);
+
+		kmem_cache_free_bulk(skbuff_head_cache, NAPI_SKB_CACHE_HALF,
+				     nc->skb_cache + NAPI_SKB_CACHE_HALF);
+		nc->skb_count = NAPI_SKB_CACHE_HALF;
+	}
+}
+
+void __kfree_skb_defer(struct sk_buff *skb)
+{
+	skb_release_all(skb);
+	napi_skb_cache_put(skb);
+}
+
+void napi_skb_free_stolen_head(struct sk_buff *skb)
+{
+	if (unlikely(skb->slow_gro)) {
+		nf_reset_ct(skb);
+		skb_dst_drop(skb);
+		skb_ext_put(skb);
+		skb_orphan(skb);
+		skb->slow_gro = 0;
+	}
+	napi_skb_cache_put(skb);
+}
+
+void napi_consume_skb(struct sk_buff *skb, int budget)
+{
+	/* Zero budget indicate non-NAPI context called us, like netpoll */
+	if (unlikely(!budget)) {
+		dev_consume_skb_any(skb);
+		return;
+	}
+
+	DEBUG_NET_WARN_ON_ONCE(!in_softirq());
+
+	if (!skb_unref(skb))
+		return;
+
+	/* if reaching here SKB is ready to free */
+	trace_consume_skb(skb);
+
+	/* if SKB is a clone, don't handle this case */
+	if (skb->fclone != SKB_FCLONE_UNAVAILABLE) {
+		__kfree_skb(skb);
+		return;
+	}
+
+	skb_release_all(skb);
+	napi_skb_cache_put(skb);
+}
+EXPORT_SYMBOL(napi_consume_skb);
+
+/* Make sure a field is contained by headers group */
+#define CHECK_SKB_FIELD(field) \
+	BUILD_BUG_ON(offsetof(struct sk_buff, field) !=		\
+		     offsetof(struct sk_buff, headers.field));	\
+
+static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
+{
+	new->tstamp		= old->tstamp;
+	/* We do not copy old->sk */
+	new->dev		= old->dev;
+	memcpy(new->cb, old->cb, sizeof(old->cb));
+	skb_dst_copy(new, old);
+	__skb_ext_copy(new, old);
+	__nf_copy(new, old, false);
+
+	/* Note : this field could be in the headers group.
+	 * It is not yet because we do not want to have a 16 bit hole
+	 */
+	new->queue_mapping = old->queue_mapping;
+
+	memcpy(&new->headers, &old->headers, sizeof(new->headers));
+	CHECK_SKB_FIELD(protocol);
+	CHECK_SKB_FIELD(csum);
+	CHECK_SKB_FIELD(hash);
+	CHECK_SKB_FIELD(priority);
+	CHECK_SKB_FIELD(skb_iif);
+	CHECK_SKB_FIELD(vlan_proto);
+	CHECK_SKB_FIELD(vlan_tci);
+	CHECK_SKB_FIELD(transport_header);
+	CHECK_SKB_FIELD(network_header);
+	CHECK_SKB_FIELD(mac_header);
+	CHECK_SKB_FIELD(inner_protocol);
+	CHECK_SKB_FIELD(inner_transport_header);
+	CHECK_SKB_FIELD(inner_network_header);
+	CHECK_SKB_FIELD(inner_mac_header);
+	CHECK_SKB_FIELD(mark);
+#ifdef CONFIG_NETWORK_SECMARK
+	CHECK_SKB_FIELD(secmark);
+#endif
+#ifdef CONFIG_NET_RX_BUSY_POLL
+	CHECK_SKB_FIELD(napi_id);
+#endif
+	CHECK_SKB_FIELD(alloc_cpu);
+#ifdef CONFIG_XPS
+	CHECK_SKB_FIELD(sender_cpu);
+#endif
+#ifdef CONFIG_NET_SCHED
+	CHECK_SKB_FIELD(tc_index);
+#endif
+
+}
+
+/*
+ * You should not add any new code to this function.  Add it to
+ * __copy_skb_header above instead.
+ */
+static struct sk_buff *__skb_clone(struct sk_buff *n, struct sk_buff *skb)
+{
+#define C(x) n->x = skb->x
+
+	n->next = n->prev = NULL;
+	n->sk = NULL;
+	__copy_skb_header(n, skb);
+
+	C(len);
+	C(data_len);
+	C(mac_len);
+	n->hdr_len = skb->nohdr ? skb_headroom(skb) : skb->hdr_len;
+	n->cloned = 1;
+	n->nohdr = 0;
+	n->peeked = 0;
+	C(pfmemalloc);
+	C(pp_recycle);
+	n->destructor = NULL;
+	C(tail);
+	C(end);
+	C(head);
+	C(head_frag);
+	C(data);
+	C(truesize);
+	refcount_set(&n->users, 1);
+
+	atomic_inc(&(skb_shinfo(skb)->dataref));
+	skb->cloned = 1;
+
+	return n;
+#undef C
+}
+
+/**
+ * alloc_skb_for_msg() - allocate sk_buff to wrap frag list forming a msg
+ * @first: first sk_buff of the msg
+ */
+struct sk_buff *alloc_skb_for_msg(struct sk_buff *first)
+{
+	struct sk_buff *n;
+
+	n = alloc_skb(0, GFP_ATOMIC);
+	if (!n)
+		return NULL;
+
+	n->len = first->len;
+	n->data_len = first->len;
+	n->truesize = first->truesize;
+
+	skb_shinfo(n)->frag_list = first;
+
+	__copy_skb_header(n, first);
+	n->destructor = NULL;
+
+	return n;
+}
+EXPORT_SYMBOL_GPL(alloc_skb_for_msg);
+
+/**
+ *	skb_morph	-	morph one skb into another
+ *	@dst: the skb to receive the contents
+ *	@src: the skb to supply the contents
+ *
+ *	This is identical to skb_clone except that the target skb is
+ *	supplied by the user.
+ *
+ *	The target skb is returned upon exit.
+ */
+struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src)
+{
+	skb_release_all(dst);
+	return __skb_clone(dst, src);
+}
+EXPORT_SYMBOL_GPL(skb_morph);
+
+int mm_account_pinned_pages(struct mmpin *mmp, size_t size)
+{
+	unsigned long max_pg, num_pg, new_pg, old_pg;
+	struct user_struct *user;
+
+	if (capable(CAP_IPC_LOCK) || !size)
+		return 0;
+
+	num_pg = (size >> PAGE_SHIFT) + 2;	/* worst case */
+	max_pg = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
+	user = mmp->user ? : current_user();
+
+	do {
+		old_pg = atomic_long_read(&user->locked_vm);
+		new_pg = old_pg + num_pg;
+		if (new_pg > max_pg)
+			return -ENOBUFS;
+	} while (atomic_long_cmpxchg(&user->locked_vm, old_pg, new_pg) !=
+		 old_pg);
+
+	if (!mmp->user) {
+		mmp->user = get_uid(user);
+		mmp->num_pg = num_pg;
+	} else {
+		mmp->num_pg += num_pg;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(mm_account_pinned_pages);
+
+void mm_unaccount_pinned_pages(struct mmpin *mmp)
+{
+	if (mmp->user) {
+		atomic_long_sub(mmp->num_pg, &mmp->user->locked_vm);
+		free_uid(mmp->user);
+	}
+}
+EXPORT_SYMBOL_GPL(mm_unaccount_pinned_pages);
+
+static struct ubuf_info *msg_zerocopy_alloc(struct sock *sk, size_t size)
+{
+	struct ubuf_info_msgzc *uarg;
+	struct sk_buff *skb;
+
+	WARN_ON_ONCE(!in_task());
+
+	skb = sock_omalloc(sk, 0, GFP_KERNEL);
+	if (!skb)
+		return NULL;
+
+	BUILD_BUG_ON(sizeof(*uarg) > sizeof(skb->cb));
+	uarg = (void *)skb->cb;
+	uarg->mmp.user = NULL;
+
+	if (mm_account_pinned_pages(&uarg->mmp, size)) {
+		kfree_skb(skb);
+		return NULL;
+	}
+
+	uarg->ubuf.callback = msg_zerocopy_callback;
+	uarg->id = ((u32)atomic_inc_return(&sk->sk_zckey)) - 1;
+	uarg->len = 1;
+	uarg->bytelen = size;
+	uarg->zerocopy = 1;
+	uarg->ubuf.flags = SKBFL_ZEROCOPY_FRAG | SKBFL_DONT_ORPHAN;
+	refcount_set(&uarg->ubuf.refcnt, 1);
+	sock_hold(sk);
+
+	return &uarg->ubuf;
+}
+
+static inline struct sk_buff *skb_from_uarg(struct ubuf_info_msgzc *uarg)
+{
+	return container_of((void *)uarg, struct sk_buff, cb);
+}
+
+struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
+				       struct ubuf_info *uarg)
+{
+	if (uarg) {
+		struct ubuf_info_msgzc *uarg_zc;
+		const u32 byte_limit = 1 << 19;		/* limit to a few TSO */
+		u32 bytelen, next;
+
+		/* there might be non MSG_ZEROCOPY users */
+		if (uarg->callback != msg_zerocopy_callback)
+			return NULL;
+
+		/* realloc only when socket is locked (TCP, UDP cork),
+		 * so uarg->len and sk_zckey access is serialized
+		 */
+		if (!sock_owned_by_user(sk)) {
+			WARN_ON_ONCE(1);
+			return NULL;
+		}
+
+		uarg_zc = uarg_to_msgzc(uarg);
+		bytelen = uarg_zc->bytelen + size;
+		if (uarg_zc->len == USHRT_MAX - 1 || bytelen > byte_limit) {
+			/* TCP can create new skb to attach new uarg */
+			if (sk->sk_type == SOCK_STREAM)
+				goto new_alloc;
+			return NULL;
+		}
+
+		next = (u32)atomic_read(&sk->sk_zckey);
+		if ((u32)(uarg_zc->id + uarg_zc->len) == next) {
+			if (mm_account_pinned_pages(&uarg_zc->mmp, size))
+				return NULL;
+			uarg_zc->len++;
+			uarg_zc->bytelen = bytelen;
+			atomic_set(&sk->sk_zckey, ++next);
+
+			/* no extra ref when appending to datagram (MSG_MORE) */
+			if (sk->sk_type == SOCK_STREAM)
+				net_zcopy_get(uarg);
+
+			return uarg;
+		}
+	}
+
+new_alloc:
+	return msg_zerocopy_alloc(sk, size);
+}
+EXPORT_SYMBOL_GPL(msg_zerocopy_realloc);
+
+static bool skb_zerocopy_notify_extend(struct sk_buff *skb, u32 lo, u16 len)
+{
+	struct sock_exterr_skb *serr = SKB_EXT_ERR(skb);
+	u32 old_lo, old_hi;
+	u64 sum_len;
+
+	old_lo = serr->ee.ee_info;
+	old_hi = serr->ee.ee_data;
+	sum_len = old_hi - old_lo + 1ULL + len;
+
+	if (sum_len >= (1ULL << 32))
+		return false;
+
+	if (lo != old_hi + 1)
+		return false;
+
+	serr->ee.ee_data += len;
+	return true;
+}
+
+static void __msg_zerocopy_callback(struct ubuf_info_msgzc *uarg)
+{
+	struct sk_buff *tail, *skb = skb_from_uarg(uarg);
+	struct sock_exterr_skb *serr;
+	struct sock *sk = skb->sk;
+	struct sk_buff_head *q;
+	unsigned long flags;
+	bool is_zerocopy;
+	u32 lo, hi;
+	u16 len;
+
+	mm_unaccount_pinned_pages(&uarg->mmp);
+
+	/* if !len, there was only 1 call, and it was aborted
+	 * so do not queue a completion notification
+	 */
+	if (!uarg->len || sock_flag(sk, SOCK_DEAD))
+		goto release;
+
+	len = uarg->len;
+	lo = uarg->id;
+	hi = uarg->id + len - 1;
+	is_zerocopy = uarg->zerocopy;
+
+	serr = SKB_EXT_ERR(skb);
+	memset(serr, 0, sizeof(*serr));
+	serr->ee.ee_errno = 0;
+	serr->ee.ee_origin = SO_EE_ORIGIN_ZEROCOPY;
+	serr->ee.ee_data = hi;
+	serr->ee.ee_info = lo;
+	if (!is_zerocopy)
+		serr->ee.ee_code |= SO_EE_CODE_ZEROCOPY_COPIED;
+
+	q = &sk->sk_error_queue;
+	spin_lock_irqsave(&q->lock, flags);
+	tail = skb_peek_tail(q);
+	if (!tail || SKB_EXT_ERR(tail)->ee.ee_origin != SO_EE_ORIGIN_ZEROCOPY ||
+	    !skb_zerocopy_notify_extend(tail, lo, len)) {
+		__skb_queue_tail(q, skb);
+		skb = NULL;
+	}
+	spin_unlock_irqrestore(&q->lock, flags);
+
+	sk_error_report(sk);
+
+release:
+	consume_skb(skb);
+	sock_put(sk);
+}
+
+void msg_zerocopy_callback(struct sk_buff *skb, struct ubuf_info *uarg,
+			   bool success)
+{
+	struct ubuf_info_msgzc *uarg_zc = uarg_to_msgzc(uarg);
+
+	uarg_zc->zerocopy = uarg_zc->zerocopy & success;
+
+	if (refcount_dec_and_test(&uarg->refcnt))
+		__msg_zerocopy_callback(uarg_zc);
+}
+EXPORT_SYMBOL_GPL(msg_zerocopy_callback);
+
+void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref)
+{
+	struct sock *sk = skb_from_uarg(uarg_to_msgzc(uarg))->sk;
+
+	atomic_dec(&sk->sk_zckey);
+	uarg_to_msgzc(uarg)->len--;
+
+	if (have_uref)
+		msg_zerocopy_callback(NULL, uarg, true);
+}
+EXPORT_SYMBOL_GPL(msg_zerocopy_put_abort);
+
+int skb_zerocopy_iter_stream(struct sock *sk, struct sk_buff *skb,
+			     struct msghdr *msg, int len,
+			     struct ubuf_info *uarg)
+{
+	struct ubuf_info *orig_uarg = skb_zcopy(skb);
+	int err, orig_len = skb->len;
+
+	/* An skb can only point to one uarg. This edge case happens when
+	 * TCP appends to an skb, but zerocopy_realloc triggered a new alloc.
+	 */
+	if (orig_uarg && uarg != orig_uarg)
+		return -EEXIST;
+
+	err = __zerocopy_sg_from_iter(msg, sk, skb, &msg->msg_iter, len);
+	if (err == -EFAULT || (err == -EMSGSIZE && skb->len == orig_len)) {
+		struct sock *save_sk = skb->sk;
+
+		/* Streams do not free skb on error. Reset to prev state. */
+		iov_iter_revert(&msg->msg_iter, skb->len - orig_len);
+		skb->sk = sk;
+		___pskb_trim(skb, orig_len);
+		skb->sk = save_sk;
+		return err;
+	}
+
+	skb_zcopy_set(skb, uarg, NULL);
+	return skb->len - orig_len;
+}
+EXPORT_SYMBOL_GPL(skb_zerocopy_iter_stream);
+
+void __skb_zcopy_downgrade_managed(struct sk_buff *skb)
+{
+	int i;
+
+	skb_shinfo(skb)->flags &= ~SKBFL_MANAGED_FRAG_REFS;
+	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
+		skb_frag_ref(skb, i);
+}
+EXPORT_SYMBOL_GPL(__skb_zcopy_downgrade_managed);
+
+static int skb_zerocopy_clone(struct sk_buff *nskb, struct sk_buff *orig,
+			      gfp_t gfp_mask)
+{
+	if (skb_zcopy(orig)) {
+		if (skb_zcopy(nskb)) {
+			/* !gfp_mask callers are verified to !skb_zcopy(nskb) */
+			if (!gfp_mask) {
+				WARN_ON_ONCE(1);
+				return -ENOMEM;
+			}
+			if (skb_uarg(nskb) == skb_uarg(orig))
+				return 0;
+			if (skb_copy_ubufs(nskb, GFP_ATOMIC))
+				return -EIO;
+		}
+		skb_zcopy_set(nskb, skb_uarg(orig), NULL);
+	}
+	return 0;
+}
+
+/**
+ *	skb_copy_ubufs	-	copy userspace skb frags buffers to kernel
+ *	@skb: the skb to modify
+ *	@gfp_mask: allocation priority
+ *
+ *	This must be called on skb with SKBFL_ZEROCOPY_ENABLE.
+ *	It will copy all frags into kernel and drop the reference
+ *	to userspace pages.
+ *
+ *	If this function is called from an interrupt gfp_mask() must be
+ *	%GFP_ATOMIC.
+ *
+ *	Returns 0 on success or a negative error code on failure
+ *	to allocate kernel memory to copy to.
+ */
+int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask)
+{
+	int num_frags = skb_shinfo(skb)->nr_frags;
+	struct page *page, *head = NULL;
+	int i, order, psize, new_frags;
+	u32 d_off;
+
+	if (skb_shared(skb) || skb_unclone(skb, gfp_mask))
+		return -EINVAL;
+
+	if (!num_frags)
+		goto release;
+
+	/* We might have to allocate high order pages, so compute what minimum
+	 * page order is needed.
+	 */
+	order = 0;
+	while ((PAGE_SIZE << order) * MAX_SKB_FRAGS < __skb_pagelen(skb))
+		order++;
+	psize = (PAGE_SIZE << order);
+
+	new_frags = (__skb_pagelen(skb) + psize - 1) >> (PAGE_SHIFT + order);
+	for (i = 0; i < new_frags; i++) {
+		page = alloc_pages(gfp_mask | __GFP_COMP, order);
+		if (!page) {
+			while (head) {
+				struct page *next = (struct page *)page_private(head);
+				put_page(head);
+				head = next;
+			}
+			return -ENOMEM;
+		}
+		set_page_private(page, (unsigned long)head);
+		head = page;
+	}
+
+	page = head;
+	d_off = 0;
+	for (i = 0; i < num_frags; i++) {
+		skb_frag_t *f = &skb_shinfo(skb)->frags[i];
+		u32 p_off, p_len, copied;
+		struct page *p;
+		u8 *vaddr;
+
+		skb_frag_foreach_page(f, skb_frag_off(f), skb_frag_size(f),
+				      p, p_off, p_len, copied) {
+			u32 copy, done = 0;
+			vaddr = kmap_atomic(p);
+
+			while (done < p_len) {
+				if (d_off == psize) {
+					d_off = 0;
+					page = (struct page *)page_private(page);
+				}
+				copy = min_t(u32, psize - d_off, p_len - done);
+				memcpy(page_address(page) + d_off,
+				       vaddr + p_off + done, copy);
+				done += copy;
+				d_off += copy;
+			}
+			kunmap_atomic(vaddr);
+		}
+	}
+
+	/* skb frags release userspace buffers */
+	for (i = 0; i < num_frags; i++)
+		skb_frag_unref(skb, i);
+
+	/* skb frags point to kernel buffers */
+	for (i = 0; i < new_frags - 1; i++) {
+		__skb_fill_page_desc(skb, i, head, 0, psize);
+		head = (struct page *)page_private(head);
+	}
+	__skb_fill_page_desc(skb, new_frags - 1, head, 0, d_off);
+	skb_shinfo(skb)->nr_frags = new_frags;
+
+release:
+	skb_zcopy_clear(skb, false);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(skb_copy_ubufs);
+
+/**
+ *	skb_clone	-	duplicate an sk_buff
+ *	@skb: buffer to clone
+ *	@gfp_mask: allocation priority
+ *
+ *	Duplicate an &sk_buff. The new one is not owned by a socket. Both
+ *	copies share the same packet data but not structure. The new
+ *	buffer has a reference count of 1. If the allocation fails the
+ *	function returns %NULL otherwise the new buffer is returned.
+ *
+ *	If this function is called from an interrupt gfp_mask() must be
+ *	%GFP_ATOMIC.
+ */
+
+struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
+{
+	struct sk_buff_fclones *fclones = container_of(skb,
+						       struct sk_buff_fclones,
+						       skb1);
+	struct sk_buff *n;
+
+	if (skb_orphan_frags(skb, gfp_mask))
+		return NULL;
+
+	if (skb->fclone == SKB_FCLONE_ORIG &&
+	    refcount_read(&fclones->fclone_ref) == 1) {
+		n = &fclones->skb2;
+		refcount_set(&fclones->fclone_ref, 2);
+		n->fclone = SKB_FCLONE_CLONE;
+	} else {
+		if (skb_pfmemalloc(skb))
+			gfp_mask |= __GFP_MEMALLOC;
+
+		n = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
+		if (!n)
+			return NULL;
+
+		n->fclone = SKB_FCLONE_UNAVAILABLE;
+	}
+
+	return __skb_clone(n, skb);
+}
+EXPORT_SYMBOL(skb_clone);
+
+void skb_headers_offset_update(struct sk_buff *skb, int off)
+{
+	/* Only adjust this if it actually is csum_start rather than csum */
+	if (skb->ip_summed == CHECKSUM_PARTIAL)
+		skb->csum_start += off;
+	/* {transport,network,mac}_header and tail are relative to skb->head */
+	skb->transport_header += off;
+	skb->network_header   += off;
+	if (skb_mac_header_was_set(skb))
+		skb->mac_header += off;
+	skb->inner_transport_header += off;
+	skb->inner_network_header += off;
+	skb->inner_mac_header += off;
+}
+EXPORT_SYMBOL(skb_headers_offset_update);
+
+void skb_copy_header(struct sk_buff *new, const struct sk_buff *old)
+{
+	__copy_skb_header(new, old);
+
+	skb_shinfo(new)->gso_size = skb_shinfo(old)->gso_size;
+	skb_shinfo(new)->gso_segs = skb_shinfo(old)->gso_segs;
+	skb_shinfo(new)->gso_type = skb_shinfo(old)->gso_type;
+}
+EXPORT_SYMBOL(skb_copy_header);
+
+static inline int skb_alloc_rx_flag(const struct sk_buff *skb)
+{
+	if (skb_pfmemalloc(skb))
+		return SKB_ALLOC_RX;
+	return 0;
+}
+
+/**
+ *	skb_copy	-	create private copy of an sk_buff
+ *	@skb: buffer to copy
+ *	@gfp_mask: allocation priority
+ *
+ *	Make a copy of both an &sk_buff and its data. This is used when the
+ *	caller wishes to modify the data and needs a private copy of the
+ *	data to alter. Returns %NULL on failure or the pointer to the buffer
+ *	on success. The returned buffer has a reference count of 1.
+ *
+ *	As by-product this function converts non-linear &sk_buff to linear
+ *	one, so that &sk_buff becomes completely private and caller is allowed
+ *	to modify all the data of returned buffer. This means that this
+ *	function is not recommended for use in circumstances when only
+ *	header is going to be modified. Use pskb_copy() instead.
+ */
+
+struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask)
+{
+	int headerlen = skb_headroom(skb);
+	unsigned int size = skb_end_offset(skb) + skb->data_len;
+	struct sk_buff *n = __alloc_skb(size, gfp_mask,
+					skb_alloc_rx_flag(skb), NUMA_NO_NODE);
+
+	if (!n)
+		return NULL;
+
+	/* Set the data pointer */
+	skb_reserve(n, headerlen);
+	/* Set the tail pointer and length */
+	skb_put(n, skb->len);
+
+	BUG_ON(skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len));
+
+	skb_copy_header(n, skb);
+	return n;
+}
+EXPORT_SYMBOL(skb_copy);
+
+/**
+ *	__pskb_copy_fclone	-  create copy of an sk_buff with private head.
+ *	@skb: buffer to copy
+ *	@headroom: headroom of new skb
+ *	@gfp_mask: allocation priority
+ *	@fclone: if true allocate the copy of the skb from the fclone
+ *	cache instead of the head cache; it is recommended to set this
+ *	to true for the cases where the copy will likely be cloned
+ *
+ *	Make a copy of both an &sk_buff and part of its data, located
+ *	in header. Fragmented data remain shared. This is used when
+ *	the caller wishes to modify only header of &sk_buff and needs
+ *	private copy of the header to alter. Returns %NULL on failure
+ *	or the pointer to the buffer on success.
+ *	The returned buffer has a reference count of 1.
+ */
+
+struct sk_buff *__pskb_copy_fclone(struct sk_buff *skb, int headroom,
+				   gfp_t gfp_mask, bool fclone)
+{
+	unsigned int size = skb_headlen(skb) + headroom;
+	int flags = skb_alloc_rx_flag(skb) | (fclone ? SKB_ALLOC_FCLONE : 0);
+	struct sk_buff *n = __alloc_skb(size, gfp_mask, flags, NUMA_NO_NODE);
+
+	if (!n)
+		goto out;
+
+	/* Set the data pointer */
+	skb_reserve(n, headroom);
+	/* Set the tail pointer and length */
+	skb_put(n, skb_headlen(skb));
+	/* Copy the bytes */
+	skb_copy_from_linear_data(skb, n->data, n->len);
+
+	n->truesize += skb->data_len;
+	n->data_len  = skb->data_len;
+	n->len	     = skb->len;
+
+	if (skb_shinfo(skb)->nr_frags) {
+		int i;
+
+		if (skb_orphan_frags(skb, gfp_mask) ||
+		    skb_zerocopy_clone(n, skb, gfp_mask)) {
+			kfree_skb(n);
+			n = NULL;
+			goto out;
+		}
+		for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+			skb_shinfo(n)->frags[i] = skb_shinfo(skb)->frags[i];
+			skb_frag_ref(skb, i);
+		}
+		skb_shinfo(n)->nr_frags = i;
+	}
+
+	if (skb_has_frag_list(skb)) {
+		skb_shinfo(n)->frag_list = skb_shinfo(skb)->frag_list;
+		skb_clone_fraglist(n);
+	}
+
+	skb_copy_header(n, skb);
+out:
+	return n;
+}
+EXPORT_SYMBOL(__pskb_copy_fclone);
+
+/**
+ *	pskb_expand_head - reallocate header of &sk_buff
+ *	@skb: buffer to reallocate
+ *	@nhead: room to add at head
+ *	@ntail: room to add at tail
+ *	@gfp_mask: allocation priority
+ *
+ *	Expands (or creates identical copy, if @nhead and @ntail are zero)
+ *	header of @skb. &sk_buff itself is not changed. &sk_buff MUST have
+ *	reference count of 1. Returns zero in the case of success or error,
+ *	if expansion failed. In the last case, &sk_buff is not changed.
+ *
+ *	All the pointers pointing into skb header may change and must be
+ *	reloaded after call to this function.
+ */
+
+int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
+		     gfp_t gfp_mask)
+{
+	unsigned int osize = skb_end_offset(skb);
+	unsigned int size = osize + nhead + ntail;
+	long off;
+	u8 *data;
+	int i;
+
+	BUG_ON(nhead < 0);
+
+	BUG_ON(skb_shared(skb));
+
+	skb_zcopy_downgrade_managed(skb);
+
+	if (skb_pfmemalloc(skb))
+		gfp_mask |= __GFP_MEMALLOC;
+
+	data = kmalloc_reserve(&size, gfp_mask, NUMA_NO_NODE, NULL);
+	if (!data)
+		goto nodata;
+	size = SKB_WITH_OVERHEAD(size);
+
+	/* Copy only real data... and, alas, header. This should be
+	 * optimized for the cases when header is void.
+	 */
+	memcpy(data + nhead, skb->head, skb_tail_pointer(skb) - skb->head);
+
+	memcpy((struct skb_shared_info *)(data + size),
+	       skb_shinfo(skb),
+	       offsetof(struct skb_shared_info, frags[skb_shinfo(skb)->nr_frags]));
+
+	/*
+	 * if shinfo is shared we must drop the old head gracefully, but if it
+	 * is not we can just drop the old head and let the existing refcount
+	 * be since all we did is relocate the values
+	 */
+	if (skb_cloned(skb)) {
+		if (skb_orphan_frags(skb, gfp_mask))
+			goto nofrags;
+		if (skb_zcopy(skb))
+			refcount_inc(&skb_uarg(skb)->refcnt);
+		for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
+			skb_frag_ref(skb, i);
+
+		if (skb_has_frag_list(skb))
+			skb_clone_fraglist(skb);
+
+		skb_release_data(skb);
+	} else {
+		skb_free_head(skb);
+	}
+	off = (data + nhead) - skb->head;
+
+	skb->head     = data;
+	skb->head_frag = 0;
+	skb->data    += off;
+
+	skb_set_end_offset(skb, size);
+#ifdef NET_SKBUFF_DATA_USES_OFFSET
+	off           = nhead;
+#endif
+	skb->tail	      += off;
+	skb_headers_offset_update(skb, nhead);
+	skb->cloned   = 0;
+	skb->hdr_len  = 0;
+	skb->nohdr    = 0;
+	atomic_set(&skb_shinfo(skb)->dataref, 1);
+
+	skb_metadata_clear(skb);
+
+	/* It is not generally safe to change skb->truesize.
+	 * For the moment, we really care of rx path, or
+	 * when skb is orphaned (not attached to a socket).
+	 */
+	if (!skb->sk || skb->destructor == sock_edemux)
+		skb->truesize += size - osize;
+
+	return 0;
+
+nofrags:
+	kfree(data);
+nodata:
+	return -ENOMEM;
+}
+EXPORT_SYMBOL(pskb_expand_head);
+
+/* Make private copy of skb with writable head and some headroom */
+
+struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom)
+{
+	struct sk_buff *skb2;
+	int delta = headroom - skb_headroom(skb);
+
+	if (delta <= 0)
+		skb2 = pskb_copy(skb, GFP_ATOMIC);
+	else {
+		skb2 = skb_clone(skb, GFP_ATOMIC);
+		if (skb2 && pskb_expand_head(skb2, SKB_DATA_ALIGN(delta), 0,
+					     GFP_ATOMIC)) {
+			kfree_skb(skb2);
+			skb2 = NULL;
+		}
+	}
+	return skb2;
+}
+EXPORT_SYMBOL(skb_realloc_headroom);
+
+int __skb_unclone_keeptruesize(struct sk_buff *skb, gfp_t pri)
+{
+	unsigned int saved_end_offset, saved_truesize;
+	struct skb_shared_info *shinfo;
+	int res;
+
+	saved_end_offset = skb_end_offset(skb);
+	saved_truesize = skb->truesize;
+
+	res = pskb_expand_head(skb, 0, 0, pri);
+	if (res)
+		return res;
+
+	skb->truesize = saved_truesize;
+
+	if (likely(skb_end_offset(skb) == saved_end_offset))
+		return 0;
+
+	shinfo = skb_shinfo(skb);
+
+	/* We are about to change back skb->end,
+	 * we need to move skb_shinfo() to its new location.
+	 */
+	memmove(skb->head + saved_end_offset,
+		shinfo,
+		offsetof(struct skb_shared_info, frags[shinfo->nr_frags]));
+
+	skb_set_end_offset(skb, saved_end_offset);
+
+	return 0;
+}
+
+/**
+ *	skb_expand_head - reallocate header of &sk_buff
+ *	@skb: buffer to reallocate
+ *	@headroom: needed headroom
+ *
+ *	Unlike skb_realloc_headroom, this one does not allocate a new skb
+ *	if possible; copies skb->sk to new skb as needed
+ *	and frees original skb in case of failures.
+ *
+ *	It expect increased headroom and generates warning otherwise.
+ */
+
+struct sk_buff *skb_expand_head(struct sk_buff *skb, unsigned int headroom)
+{
+	int delta = headroom - skb_headroom(skb);
+	int osize = skb_end_offset(skb);
+	struct sock *sk = skb->sk;
+
+	if (WARN_ONCE(delta <= 0,
+		      "%s is expecting an increase in the headroom", __func__))
+		return skb;
+
+	delta = SKB_DATA_ALIGN(delta);
+	/* pskb_expand_head() might crash, if skb is shared. */
+	if (skb_shared(skb) || !is_skb_wmem(skb)) {
+		struct sk_buff *nskb = skb_clone(skb, GFP_ATOMIC);
+
+		if (unlikely(!nskb))
+			goto fail;
+
+		if (sk)
+			skb_set_owner_w(nskb, sk);
+		consume_skb(skb);
+		skb = nskb;
+	}
+	if (pskb_expand_head(skb, delta, 0, GFP_ATOMIC))
+		goto fail;
+
+	if (sk && is_skb_wmem(skb)) {
+		delta = skb_end_offset(skb) - osize;
+		refcount_add(delta, &sk->sk_wmem_alloc);
+		skb->truesize += delta;
+	}
+	return skb;
+
+fail:
+	kfree_skb(skb);
+	return NULL;
+}
+EXPORT_SYMBOL(skb_expand_head);
+
+/**
+ *	skb_copy_expand	-	copy and expand sk_buff
+ *	@skb: buffer to copy
+ *	@newheadroom: new free bytes at head
+ *	@newtailroom: new free bytes at tail
+ *	@gfp_mask: allocation priority
+ *
+ *	Make a copy of both an &sk_buff and its data and while doing so
+ *	allocate additional space.
+ *
+ *	This is used when the caller wishes to modify the data and needs a
+ *	private copy of the data to alter as well as more space for new fields.
+ *	Returns %NULL on failure or the pointer to the buffer
+ *	on success. The returned buffer has a reference count of 1.
+ *
+ *	You must pass %GFP_ATOMIC as the allocation priority if this function
+ *	is called from an interrupt.
+ */
+struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
+				int newheadroom, int newtailroom,
+				gfp_t gfp_mask)
+{
+	/*
+	 *	Allocate the copy buffer
+	 */
+	struct sk_buff *n = __alloc_skb(newheadroom + skb->len + newtailroom,
+					gfp_mask, skb_alloc_rx_flag(skb),
+					NUMA_NO_NODE);
+	int oldheadroom = skb_headroom(skb);
+	int head_copy_len, head_copy_off;
+
+	if (!n)
+		return NULL;
+
+	skb_reserve(n, newheadroom);
+
+	/* Set the tail pointer and length */
+	skb_put(n, skb->len);
+
+	head_copy_len = oldheadroom;
+	head_copy_off = 0;
+	if (newheadroom <= head_copy_len)
+		head_copy_len = newheadroom;
+	else
+		head_copy_off = newheadroom - head_copy_len;
+
+	/* Copy the linear header and data. */
+	BUG_ON(skb_copy_bits(skb, -head_copy_len, n->head + head_copy_off,
+			     skb->len + head_copy_len));
+
+	skb_copy_header(n, skb);
+
+	skb_headers_offset_update(n, newheadroom - oldheadroom);
+
+	return n;
+}
+EXPORT_SYMBOL(skb_copy_expand);
+
+/**
+ *	__skb_pad		-	zero pad the tail of an skb
+ *	@skb: buffer to pad
+ *	@pad: space to pad
+ *	@free_on_error: free buffer on error
+ *
+ *	Ensure that a buffer is followed by a padding area that is zero
+ *	filled. Used by network drivers which may DMA or transfer data
+ *	beyond the buffer end onto the wire.
+ *
+ *	May return error in out of memory cases. The skb is freed on error
+ *	if @free_on_error is true.
+ */
+
+int __skb_pad(struct sk_buff *skb, int pad, bool free_on_error)
+{
+	int err;
+	int ntail;
+
+	/* If the skbuff is non linear tailroom is always zero.. */
+	if (!skb_cloned(skb) && skb_tailroom(skb) >= pad) {
+		memset(skb->data+skb->len, 0, pad);
+		return 0;
+	}
+
+	ntail = skb->data_len + pad - (skb->end - skb->tail);
+	if (likely(skb_cloned(skb) || ntail > 0)) {
+		err = pskb_expand_head(skb, 0, ntail, GFP_ATOMIC);
+		if (unlikely(err))
+			goto free_skb;
+	}
+
+	/* FIXME: The use of this function with non-linear skb's really needs
+	 * to be audited.
+	 */
+	err = skb_linearize(skb);
+	if (unlikely(err))
+		goto free_skb;
+
+	memset(skb->data + skb->len, 0, pad);
+	return 0;
+
+free_skb:
+	if (free_on_error)
+		kfree_skb(skb);
+	return err;
+}
+EXPORT_SYMBOL(__skb_pad);
+
+/**
+ *	pskb_put - add data to the tail of a potentially fragmented buffer
+ *	@skb: start of the buffer to use
+ *	@tail: tail fragment of the buffer to use
+ *	@len: amount of data to add
+ *
+ *	This function extends the used data area of the potentially
+ *	fragmented buffer. @tail must be the last fragment of @skb -- or
+ *	@skb itself. If this would exceed the total buffer size the kernel
+ *	will panic. A pointer to the first byte of the extra data is
+ *	returned.
+ */
+
+void *pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len)
+{
+	if (tail != skb) {
+		skb->data_len += len;
+		skb->len += len;
+	}
+	return skb_put(tail, len);
+}
+EXPORT_SYMBOL_GPL(pskb_put);
+
+/**
+ *	skb_put - add data to a buffer
+ *	@skb: buffer to use
+ *	@len: amount of data to add
+ *
+ *	This function extends the used data area of the buffer. If this would
+ *	exceed the total buffer size the kernel will panic. A pointer to the
+ *	first byte of the extra data is returned.
+ */
+void *skb_put(struct sk_buff *skb, unsigned int len)
+{
+	void *tmp = skb_tail_pointer(skb);
+	SKB_LINEAR_ASSERT(skb);
+	skb->tail += len;
+	skb->len  += len;
+	if (unlikely(skb->tail > skb->end))
+		skb_over_panic(skb, len, __builtin_return_address(0));
+	return tmp;
+}
+EXPORT_SYMBOL(skb_put);
+
+/**
+ *	skb_push - add data to the start of a buffer
+ *	@skb: buffer to use
+ *	@len: amount of data to add
+ *
+ *	This function extends the used data area of the buffer at the buffer
+ *	start. If this would exceed the total buffer headroom the kernel will
+ *	panic. A pointer to the first byte of the extra data is returned.
+ */
+void *skb_push(struct sk_buff *skb, unsigned int len)
+{
+	skb->data -= len;
+	skb->len  += len;
+	if (unlikely(skb->data < skb->head))
+		skb_under_panic(skb, len, __builtin_return_address(0));
+	return skb->data;
+}
+EXPORT_SYMBOL(skb_push);
+
+/**
+ *	skb_pull - remove data from the start of a buffer
+ *	@skb: buffer to use
+ *	@len: amount of data to remove
+ *
+ *	This function removes data from the start of a buffer, returning
+ *	the memory to the headroom. A pointer to the next data in the buffer
+ *	is returned. Once the data has been pulled future pushes will overwrite
+ *	the old data.
+ */
+void *skb_pull(struct sk_buff *skb, unsigned int len)
+{
+	return skb_pull_inline(skb, len);
+}
+EXPORT_SYMBOL(skb_pull);
+
+/**
+ *	skb_pull_data - remove data from the start of a buffer returning its
+ *	original position.
+ *	@skb: buffer to use
+ *	@len: amount of data to remove
+ *
+ *	This function removes data from the start of a buffer, returning
+ *	the memory to the headroom. A pointer to the original data in the buffer
+ *	is returned after checking if there is enough data to pull. Once the
+ *	data has been pulled future pushes will overwrite the old data.
+ */
+void *skb_pull_data(struct sk_buff *skb, size_t len)
+{
+	void *data = skb->data;
+
+	if (skb->len < len)
+		return NULL;
+
+	skb_pull(skb, len);
+
+	return data;
+}
+EXPORT_SYMBOL(skb_pull_data);
+
+/**
+ *	skb_trim - remove end from a buffer
+ *	@skb: buffer to alter
+ *	@len: new length
+ *
+ *	Cut the length of a buffer down by removing data from the tail. If
+ *	the buffer is already under the length specified it is not modified.
+ *	The skb must be linear.
+ */
+void skb_trim(struct sk_buff *skb, unsigned int len)
+{
+	if (skb->len > len)
+		__skb_trim(skb, len);
+}
+EXPORT_SYMBOL(skb_trim);
+
+/* Trims skb to length len. It can change skb pointers.
+ */
+
+int ___pskb_trim(struct sk_buff *skb, unsigned int len)
+{
+	struct sk_buff **fragp;
+	struct sk_buff *frag;
+	int offset = skb_headlen(skb);
+	int nfrags = skb_shinfo(skb)->nr_frags;
+	int i;
+	int err;
+
+	if (skb_cloned(skb) &&
+	    unlikely((err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC))))
+		return err;
+
+	i = 0;
+	if (offset >= len)
+		goto drop_pages;
+
+	for (; i < nfrags; i++) {
+		int end = offset + skb_frag_size(&skb_shinfo(skb)->frags[i]);
+
+		if (end < len) {
+			offset = end;
+			continue;
+		}
+
+		skb_frag_size_set(&skb_shinfo(skb)->frags[i++], len - offset);
+
+drop_pages:
+		skb_shinfo(skb)->nr_frags = i;
+
+		for (; i < nfrags; i++)
+			skb_frag_unref(skb, i);
+
+		if (skb_has_frag_list(skb))
+			skb_drop_fraglist(skb);
+		goto done;
+	}
+
+	for (fragp = &skb_shinfo(skb)->frag_list; (frag = *fragp);
+	     fragp = &frag->next) {
+		int end = offset + frag->len;
+
+		if (skb_shared(frag)) {
+			struct sk_buff *nfrag;
+
+			nfrag = skb_clone(frag, GFP_ATOMIC);
+			if (unlikely(!nfrag))
+				return -ENOMEM;
+
+			nfrag->next = frag->next;
+			consume_skb(frag);
+			frag = nfrag;
+			*fragp = frag;
+		}
+
+		if (end < len) {
+			offset = end;
+			continue;
+		}
+
+		if (end > len &&
+		    unlikely((err = pskb_trim(frag, len - offset))))
+			return err;
+
+		if (frag->next)
+			skb_drop_list(&frag->next);
+		break;
+	}
+
+done:
+	if (len > skb_headlen(skb)) {
+		skb->data_len -= skb->len - len;
+		skb->len       = len;
+	} else {
+		skb->len       = len;
+		skb->data_len  = 0;
+		skb_set_tail_pointer(skb, len);
+	}
+
+	if (!skb->sk || skb->destructor == sock_edemux)
+		skb_condense(skb);
+	return 0;
+}
+EXPORT_SYMBOL(___pskb_trim);
+
+/* Note : use pskb_trim_rcsum() instead of calling this directly
+ */
+int pskb_trim_rcsum_slow(struct sk_buff *skb, unsigned int len)
+{
+	if (skb->ip_summed == CHECKSUM_COMPLETE) {
+		int delta = skb->len - len;
+
+		skb->csum = csum_block_sub(skb->csum,
+					   skb_checksum(skb, len, delta, 0),
+					   len);
+	} else if (skb->ip_summed == CHECKSUM_PARTIAL) {
+		int hdlen = (len > skb_headlen(skb)) ? skb_headlen(skb) : len;
+		int offset = skb_checksum_start_offset(skb) + skb->csum_offset;
+
+		if (offset + sizeof(__sum16) > hdlen)
+			return -EINVAL;
+	}
+	return __pskb_trim(skb, len);
+}
+EXPORT_SYMBOL(pskb_trim_rcsum_slow);
+
+/**
+ *	__pskb_pull_tail - advance tail of skb header
+ *	@skb: buffer to reallocate
+ *	@delta: number of bytes to advance tail
+ *
+ *	The function makes a sense only on a fragmented &sk_buff,
+ *	it expands header moving its tail forward and copying necessary
+ *	data from fragmented part.
+ *
+ *	&sk_buff MUST have reference count of 1.
+ *
+ *	Returns %NULL (and &sk_buff does not change) if pull failed
+ *	or value of new tail of skb in the case of success.
+ *
+ *	All the pointers pointing into skb header may change and must be
+ *	reloaded after call to this function.
+ */
+
+/* Moves tail of skb head forward, copying data from fragmented part,
+ * when it is necessary.
+ * 1. It may fail due to malloc failure.
+ * 2. It may change skb pointers.
+ *
+ * It is pretty complicated. Luckily, it is called only in exceptional cases.
+ */
+void *__pskb_pull_tail(struct sk_buff *skb, int delta)
+{
+	/* If skb has not enough free space at tail, get new one
+	 * plus 128 bytes for future expansions. If we have enough
+	 * room at tail, reallocate without expansion only if skb is cloned.
+	 */
+	int i, k, eat = (skb->tail + delta) - skb->end;
+
+	if (eat > 0 || skb_cloned(skb)) {
+		if (pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0,
+				     GFP_ATOMIC))
+			return NULL;
+	}
+
+	BUG_ON(skb_copy_bits(skb, skb_headlen(skb),
+			     skb_tail_pointer(skb), delta));
+
+	/* Optimization: no fragments, no reasons to preestimate
+	 * size of pulled pages. Superb.
+	 */
+	if (!skb_has_frag_list(skb))
+		goto pull_pages;
+
+	/* Estimate size of pulled pages. */
+	eat = delta;
+	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+		int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
+
+		if (size >= eat)
+			goto pull_pages;
+		eat -= size;
+	}
+
+	/* If we need update frag list, we are in troubles.
+	 * Certainly, it is possible to add an offset to skb data,
+	 * but taking into account that pulling is expected to
+	 * be very rare operation, it is worth to fight against
+	 * further bloating skb head and crucify ourselves here instead.
+	 * Pure masohism, indeed. 8)8)
+	 */
+	if (eat) {
+		struct sk_buff *list = skb_shinfo(skb)->frag_list;
+		struct sk_buff *clone = NULL;
+		struct sk_buff *insp = NULL;
+
+		do {
+			if (list->len <= eat) {
+				/* Eaten as whole. */
+				eat -= list->len;
+				list = list->next;
+				insp = list;
+			} else {
+				/* Eaten partially. */
+				if (skb_is_gso(skb) && !list->head_frag &&
+				    skb_headlen(list))
+					skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
+
+				if (skb_shared(list)) {
+					/* Sucks! We need to fork list. :-( */
+					clone = skb_clone(list, GFP_ATOMIC);
+					if (!clone)
+						return NULL;
+					insp = list->next;
+					list = clone;
+				} else {
+					/* This may be pulled without
+					 * problems. */
+					insp = list;
+				}
+				if (!pskb_pull(list, eat)) {
+					kfree_skb(clone);
+					return NULL;
+				}
+				break;
+			}
+		} while (eat);
+
+		/* Free pulled out fragments. */
+		while ((list = skb_shinfo(skb)->frag_list) != insp) {
+			skb_shinfo(skb)->frag_list = list->next;
+			consume_skb(list);
+		}
+		/* And insert new clone at head. */
+		if (clone) {
+			clone->next = list;
+			skb_shinfo(skb)->frag_list = clone;
+		}
+	}
+	/* Success! Now we may commit changes to skb data. */
+
+pull_pages:
+	eat = delta;
+	k = 0;
+	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+		int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
+
+		if (size <= eat) {
+			skb_frag_unref(skb, i);
+			eat -= size;
+		} else {
+			skb_frag_t *frag = &skb_shinfo(skb)->frags[k];
+
+			*frag = skb_shinfo(skb)->frags[i];
+			if (eat) {
+				skb_frag_off_add(frag, eat);
+				skb_frag_size_sub(frag, eat);
+				if (!i)
+					goto end;
+				eat = 0;
+			}
+			k++;
+		}
+	}
+	skb_shinfo(skb)->nr_frags = k;
+
+end:
+	skb->tail     += delta;
+	skb->data_len -= delta;
+
+	if (!skb->data_len)
+		skb_zcopy_clear(skb, false);
+
+	return skb_tail_pointer(skb);
+}
+EXPORT_SYMBOL(__pskb_pull_tail);
+
+/**
+ *	skb_copy_bits - copy bits from skb to kernel buffer
+ *	@skb: source skb
+ *	@offset: offset in source
+ *	@to: destination buffer
+ *	@len: number of bytes to copy
+ *
+ *	Copy the specified number of bytes from the source skb to the
+ *	destination buffer.
+ *
+ *	CAUTION ! :
+ *		If its prototype is ever changed,
+ *		check arch/{*}/net/{*}.S files,
+ *		since it is called from BPF assembly code.
+ */
+int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len)
+{
+	int start = skb_headlen(skb);
+	struct sk_buff *frag_iter;
+	int i, copy;
+
+	if (offset > (int)skb->len - len)
+		goto fault;
+
+	/* Copy header. */
+	if ((copy = start - offset) > 0) {
+		if (copy > len)
+			copy = len;
+		skb_copy_from_linear_data_offset(skb, offset, to, copy);
+		if ((len -= copy) == 0)
+			return 0;
+		offset += copy;
+		to     += copy;
+	}
+
+	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+		int end;
+		skb_frag_t *f = &skb_shinfo(skb)->frags[i];
+
+		WARN_ON(start > offset + len);
+
+		end = start + skb_frag_size(f);
+		if ((copy = end - offset) > 0) {
+			u32 p_off, p_len, copied;
+			struct page *p;
+			u8 *vaddr;
+
+			if (copy > len)
+				copy = len;
+
+			skb_frag_foreach_page(f,
+					      skb_frag_off(f) + offset - start,
+					      copy, p, p_off, p_len, copied) {
+				vaddr = kmap_atomic(p);
+				memcpy(to + copied, vaddr + p_off, p_len);
+				kunmap_atomic(vaddr);
+			}
+
+			if ((len -= copy) == 0)
+				return 0;
+			offset += copy;
+			to     += copy;
+		}
+		start = end;
+	}
+
+	skb_walk_frags(skb, frag_iter) {
+		int end;
+
+		WARN_ON(start > offset + len);
+
+		end = start + frag_iter->len;
+		if ((copy = end - offset) > 0) {
+			if (copy > len)
+				copy = len;
+			if (skb_copy_bits(frag_iter, offset - start, to, copy))
+				goto fault;
+			if ((len -= copy) == 0)
+				return 0;
+			offset += copy;
+			to     += copy;
+		}
+		start = end;
+	}
+
+	if (!len)
+		return 0;
+
+fault:
+	return -EFAULT;
+}
+EXPORT_SYMBOL(skb_copy_bits);
+
+/*
+ * Callback from splice_to_pipe(), if we need to release some pages
+ * at the end of the spd in case we error'ed out in filling the pipe.
+ */
+static void sock_spd_release(struct splice_pipe_desc *spd, unsigned int i)
+{
+	put_page(spd->pages[i]);
+}
+
+static struct page *linear_to_page(struct page *page, unsigned int *len,
+				   unsigned int *offset,
+				   struct sock *sk)
+{
+	struct page_frag *pfrag = sk_page_frag(sk);
+
+	if (!sk_page_frag_refill(sk, pfrag))
+		return NULL;
+
+	*len = min_t(unsigned int, *len, pfrag->size - pfrag->offset);
+
+	memcpy(page_address(pfrag->page) + pfrag->offset,
+	       page_address(page) + *offset, *len);
+	*offset = pfrag->offset;
+	pfrag->offset += *len;
+
+	return pfrag->page;
+}
+
+static bool spd_can_coalesce(const struct splice_pipe_desc *spd,
+			     struct page *page,
+			     unsigned int offset)
+{
+	return	spd->nr_pages &&
+		spd->pages[spd->nr_pages - 1] == page &&
+		(spd->partial[spd->nr_pages - 1].offset +
+		 spd->partial[spd->nr_pages - 1].len == offset);
+}
+
+/*
+ * Fill page/offset/length into spd, if it can hold more pages.
+ */
+static bool spd_fill_page(struct splice_pipe_desc *spd,
+			  struct pipe_inode_info *pipe, struct page *page,
+			  unsigned int *len, unsigned int offset,
+			  bool linear,
+			  struct sock *sk)
+{
+	if (unlikely(spd->nr_pages == MAX_SKB_FRAGS))
+		return true;
+
+	if (linear) {
+		page = linear_to_page(page, len, &offset, sk);
+		if (!page)
+			return true;
+	}
+	if (spd_can_coalesce(spd, page, offset)) {
+		spd->partial[spd->nr_pages - 1].len += *len;
+		return false;
+	}
+	get_page(page);
+	spd->pages[spd->nr_pages] = page;
+	spd->partial[spd->nr_pages].len = *len;
+	spd->partial[spd->nr_pages].offset = offset;
+	spd->nr_pages++;
+
+	return false;
+}
+
+static bool __splice_segment(struct page *page, unsigned int poff,
+			     unsigned int plen, unsigned int *off,
+			     unsigned int *len,
+			     struct splice_pipe_desc *spd, bool linear,
+			     struct sock *sk,
+			     struct pipe_inode_info *pipe)
+{
+	if (!*len)
+		return true;
+
+	/* skip this segment if already processed */
+	if (*off >= plen) {
+		*off -= plen;
+		return false;
+	}
+
+	/* ignore any bits we already processed */
+	poff += *off;
+	plen -= *off;
+	*off = 0;
+
+	do {
+		unsigned int flen = min(*len, plen);
+
+		if (spd_fill_page(spd, pipe, page, &flen, poff,
+				  linear, sk))
+			return true;
+		poff += flen;
+		plen -= flen;
+		*len -= flen;
+	} while (*len && plen);
+
+	return false;
+}
+
+/*
+ * Map linear and fragment data from the skb to spd. It reports true if the
+ * pipe is full or if we already spliced the requested length.
+ */
+static bool __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe,
+			      unsigned int *offset, unsigned int *len,
+			      struct splice_pipe_desc *spd, struct sock *sk)
+{
+	int seg;
+	struct sk_buff *iter;
+
+	/* map the linear part :
+	 * If skb->head_frag is set, this 'linear' part is backed by a
+	 * fragment, and if the head is not shared with any clones then
+	 * we can avoid a copy since we own the head portion of this page.
+	 */
+	if (__splice_segment(virt_to_page(skb->data),
+			     (unsigned long) skb->data & (PAGE_SIZE - 1),
+			     skb_headlen(skb),
+			     offset, len, spd,
+			     skb_head_is_locked(skb),
+			     sk, pipe))
+		return true;
+
+	/*
+	 * then map the fragments
+	 */
+	for (seg = 0; seg < skb_shinfo(skb)->nr_frags; seg++) {
+		const skb_frag_t *f = &skb_shinfo(skb)->frags[seg];
+
+		if (__splice_segment(skb_frag_page(f),
+				     skb_frag_off(f), skb_frag_size(f),
+				     offset, len, spd, false, sk, pipe))
+			return true;
+	}
+
+	skb_walk_frags(skb, iter) {
+		if (*offset >= iter->len) {
+			*offset -= iter->len;
+			continue;
+		}
+		/* __skb_splice_bits() only fails if the output has no room
+		 * left, so no point in going over the frag_list for the error
+		 * case.
+		 */
+		if (__skb_splice_bits(iter, pipe, offset, len, spd, sk))
+			return true;
+	}
+
+	return false;
+}
+
+/*
+ * Map data from the skb to a pipe. Should handle both the linear part,
+ * the fragments, and the frag list.
+ */
+int skb_splice_bits(struct sk_buff *skb, struct sock *sk, unsigned int offset,
+		    struct pipe_inode_info *pipe, unsigned int tlen,
+		    unsigned int flags)
+{
+	struct partial_page partial[MAX_SKB_FRAGS];
+	struct page *pages[MAX_SKB_FRAGS];
+	struct splice_pipe_desc spd = {
+		.pages = pages,
+		.partial = partial,
+		.nr_pages_max = MAX_SKB_FRAGS,
+		.ops = &nosteal_pipe_buf_ops,
+		.spd_release = sock_spd_release,
+	};
+	int ret = 0;
+
+	__skb_splice_bits(skb, pipe, &offset, &tlen, &spd, sk);
+
+	if (spd.nr_pages)
+		ret = splice_to_pipe(pipe, &spd);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(skb_splice_bits);
+
+static int sendmsg_unlocked(struct sock *sk, struct msghdr *msg,
+			    struct kvec *vec, size_t num, size_t size)
+{
+	struct socket *sock = sk->sk_socket;
+
+	if (!sock)
+		return -EINVAL;
+	return kernel_sendmsg(sock, msg, vec, num, size);
+}
+
+static int sendpage_unlocked(struct sock *sk, struct page *page, int offset,
+			     size_t size, int flags)
+{
+	struct socket *sock = sk->sk_socket;
+
+	if (!sock)
+		return -EINVAL;
+	return kernel_sendpage(sock, page, offset, size, flags);
+}
+
+typedef int (*sendmsg_func)(struct sock *sk, struct msghdr *msg,
+			    struct kvec *vec, size_t num, size_t size);
+typedef int (*sendpage_func)(struct sock *sk, struct page *page, int offset,
+			     size_t size, int flags);
+static int __skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset,
+			   int len, sendmsg_func sendmsg, sendpage_func sendpage)
+{
+	unsigned int orig_len = len;
+	struct sk_buff *head = skb;
+	unsigned short fragidx;
+	int slen, ret;
+
+do_frag_list:
+
+	/* Deal with head data */
+	while (offset < skb_headlen(skb) && len) {
+		struct kvec kv;
+		struct msghdr msg;
+
+		slen = min_t(int, len, skb_headlen(skb) - offset);
+		kv.iov_base = skb->data + offset;
+		kv.iov_len = slen;
+		memset(&msg, 0, sizeof(msg));
+		msg.msg_flags = MSG_DONTWAIT;
+
+		ret = INDIRECT_CALL_2(sendmsg, kernel_sendmsg_locked,
+				      sendmsg_unlocked, sk, &msg, &kv, 1, slen);
+		if (ret <= 0)
+			goto error;
+
+		offset += ret;
+		len -= ret;
+	}
+
+	/* All the data was skb head? */
+	if (!len)
+		goto out;
+
+	/* Make offset relative to start of frags */
+	offset -= skb_headlen(skb);
+
+	/* Find where we are in frag list */
+	for (fragidx = 0; fragidx < skb_shinfo(skb)->nr_frags; fragidx++) {
+		skb_frag_t *frag  = &skb_shinfo(skb)->frags[fragidx];
+
+		if (offset < skb_frag_size(frag))
+			break;
+
+		offset -= skb_frag_size(frag);
+	}
+
+	for (; len && fragidx < skb_shinfo(skb)->nr_frags; fragidx++) {
+		skb_frag_t *frag  = &skb_shinfo(skb)->frags[fragidx];
+
+		slen = min_t(size_t, len, skb_frag_size(frag) - offset);
+
+		while (slen) {
+			ret = INDIRECT_CALL_2(sendpage, kernel_sendpage_locked,
+					      sendpage_unlocked, sk,
+					      skb_frag_page(frag),
+					      skb_frag_off(frag) + offset,
+					      slen, MSG_DONTWAIT);
+			if (ret <= 0)
+				goto error;
+
+			len -= ret;
+			offset += ret;
+			slen -= ret;
+		}
+
+		offset = 0;
+	}
+
+	if (len) {
+		/* Process any frag lists */
+
+		if (skb == head) {
+			if (skb_has_frag_list(skb)) {
+				skb = skb_shinfo(skb)->frag_list;
+				goto do_frag_list;
+			}
+		} else if (skb->next) {
+			skb = skb->next;
+			goto do_frag_list;
+		}
+	}
+
+out:
+	return orig_len - len;
+
+error:
+	return orig_len == len ? ret : orig_len - len;
+}
+
+/* Send skb data on a socket. Socket must be locked. */
+int skb_send_sock_locked(struct sock *sk, struct sk_buff *skb, int offset,
+			 int len)
+{
+	return __skb_send_sock(sk, skb, offset, len, kernel_sendmsg_locked,
+			       kernel_sendpage_locked);
+}
+EXPORT_SYMBOL_GPL(skb_send_sock_locked);
+
+/* Send skb data on a socket. Socket must be unlocked. */
+int skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset, int len)
+{
+	return __skb_send_sock(sk, skb, offset, len, sendmsg_unlocked,
+			       sendpage_unlocked);
+}
+
+/**
+ *	skb_store_bits - store bits from kernel buffer to skb
+ *	@skb: destination buffer
+ *	@offset: offset in destination
+ *	@from: source buffer
+ *	@len: number of bytes to copy
+ *
+ *	Copy the specified number of bytes from the source buffer to the
+ *	destination skb.  This function handles all the messy bits of
+ *	traversing fragment lists and such.
+ */
+
+int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len)
+{
+	int start = skb_headlen(skb);
+	struct sk_buff *frag_iter;
+	int i, copy;
+
+	if (offset > (int)skb->len - len)
+		goto fault;
+
+	if ((copy = start - offset) > 0) {
+		if (copy > len)
+			copy = len;
+		skb_copy_to_linear_data_offset(skb, offset, from, copy);
+		if ((len -= copy) == 0)
+			return 0;
+		offset += copy;
+		from += copy;
+	}
+
+	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+		skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
+		int end;
+
+		WARN_ON(start > offset + len);
+
+		end = start + skb_frag_size(frag);
+		if ((copy = end - offset) > 0) {
+			u32 p_off, p_len, copied;
+			struct page *p;
+			u8 *vaddr;
+
+			if (copy > len)
+				copy = len;
+
+			skb_frag_foreach_page(frag,
+					      skb_frag_off(frag) + offset - start,
+					      copy, p, p_off, p_len, copied) {
+				vaddr = kmap_atomic(p);
+				memcpy(vaddr + p_off, from + copied, p_len);
+				kunmap_atomic(vaddr);
+			}
+
+			if ((len -= copy) == 0)
+				return 0;
+			offset += copy;
+			from += copy;
+		}
+		start = end;
+	}
+
+	skb_walk_frags(skb, frag_iter) {
+		int end;
+
+		WARN_ON(start > offset + len);
+
+		end = start + frag_iter->len;
+		if ((copy = end - offset) > 0) {
+			if (copy > len)
+				copy = len;
+			if (skb_store_bits(frag_iter, offset - start,
+					   from, copy))
+				goto fault;
+			if ((len -= copy) == 0)
+				return 0;
+			offset += copy;
+			from += copy;
+		}
+		start = end;
+	}
+	if (!len)
+		return 0;
+
+fault:
+	return -EFAULT;
+}
+EXPORT_SYMBOL(skb_store_bits);
+
+/* Checksum skb data. */
+__wsum __skb_checksum(const struct sk_buff *skb, int offset, int len,
+		      __wsum csum, const struct skb_checksum_ops *ops)
+{
+	int start = skb_headlen(skb);
+	int i, copy = start - offset;
+	struct sk_buff *frag_iter;
+	int pos = 0;
+
+	/* Checksum header. */
+	if (copy > 0) {
+		if (copy > len)
+			copy = len;
+		csum = INDIRECT_CALL_1(ops->update, csum_partial_ext,
+				       skb->data + offset, copy, csum);
+		if ((len -= copy) == 0)
+			return csum;
+		offset += copy;
+		pos	= copy;
+	}
+
+	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+		int end;
+		skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
+
+		WARN_ON(start > offset + len);
+
+		end = start + skb_frag_size(frag);
+		if ((copy = end - offset) > 0) {
+			u32 p_off, p_len, copied;
+			struct page *p;
+			__wsum csum2;
+			u8 *vaddr;
+
+			if (copy > len)
+				copy = len;
+
+			skb_frag_foreach_page(frag,
+					      skb_frag_off(frag) + offset - start,
+					      copy, p, p_off, p_len, copied) {
+				vaddr = kmap_atomic(p);
+				csum2 = INDIRECT_CALL_1(ops->update,
+							csum_partial_ext,
+							vaddr + p_off, p_len, 0);
+				kunmap_atomic(vaddr);
+				csum = INDIRECT_CALL_1(ops->combine,
+						       csum_block_add_ext, csum,
+						       csum2, pos, p_len);
+				pos += p_len;
+			}
+
+			if (!(len -= copy))
+				return csum;
+			offset += copy;
+		}
+		start = end;
+	}
+
+	skb_walk_frags(skb, frag_iter) {
+		int end;
+
+		WARN_ON(start > offset + len);
+
+		end = start + frag_iter->len;
+		if ((copy = end - offset) > 0) {
+			__wsum csum2;
+			if (copy > len)
+				copy = len;
+			csum2 = __skb_checksum(frag_iter, offset - start,
+					       copy, 0, ops);
+			csum = INDIRECT_CALL_1(ops->combine, csum_block_add_ext,
+					       csum, csum2, pos, copy);
+			if ((len -= copy) == 0)
+				return csum;
+			offset += copy;
+			pos    += copy;
+		}
+		start = end;
+	}
+	BUG_ON(len);
+
+	return csum;
+}
+EXPORT_SYMBOL(__skb_checksum);
+
+__wsum skb_checksum(const struct sk_buff *skb, int offset,
+		    int len, __wsum csum)
+{
+	const struct skb_checksum_ops ops = {
+		.update  = csum_partial_ext,
+		.combine = csum_block_add_ext,
+	};
+
+	return __skb_checksum(skb, offset, len, csum, &ops);
+}
+EXPORT_SYMBOL(skb_checksum);
+
+/* Both of above in one bottle. */
+
+__wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset,
+				    u8 *to, int len)
+{
+	int start = skb_headlen(skb);
+	int i, copy = start - offset;
+	struct sk_buff *frag_iter;
+	int pos = 0;
+	__wsum csum = 0;
+
+	/* Copy header. */
+	if (copy > 0) {
+		if (copy > len)
+			copy = len;
+		csum = csum_partial_copy_nocheck(skb->data + offset, to,
+						 copy);
+		if ((len -= copy) == 0)
+			return csum;
+		offset += copy;
+		to     += copy;
+		pos	= copy;
+	}
+
+	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+		int end;
+
+		WARN_ON(start > offset + len);
+
+		end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]);
+		if ((copy = end - offset) > 0) {
+			skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
+			u32 p_off, p_len, copied;
+			struct page *p;
+			__wsum csum2;
+			u8 *vaddr;
+
+			if (copy > len)
+				copy = len;
+
+			skb_frag_foreach_page(frag,
+					      skb_frag_off(frag) + offset - start,
+					      copy, p, p_off, p_len, copied) {
+				vaddr = kmap_atomic(p);
+				csum2 = csum_partial_copy_nocheck(vaddr + p_off,
+								  to + copied,
+								  p_len);
+				kunmap_atomic(vaddr);
+				csum = csum_block_add(csum, csum2, pos);
+				pos += p_len;
+			}
+
+			if (!(len -= copy))
+				return csum;
+			offset += copy;
+			to     += copy;
+		}
+		start = end;
+	}
+
+	skb_walk_frags(skb, frag_iter) {
+		__wsum csum2;
+		int end;
+
+		WARN_ON(start > offset + len);
+
+		end = start + frag_iter->len;
+		if ((copy = end - offset) > 0) {
+			if (copy > len)
+				copy = len;
+			csum2 = skb_copy_and_csum_bits(frag_iter,
+						       offset - start,
+						       to, copy);
+			csum = csum_block_add(csum, csum2, pos);
+			if ((len -= copy) == 0)
+				return csum;
+			offset += copy;
+			to     += copy;
+			pos    += copy;
+		}
+		start = end;
+	}
+	BUG_ON(len);
+	return csum;
+}
+EXPORT_SYMBOL(skb_copy_and_csum_bits);
+
+__sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len)
+{
+	__sum16 sum;
+
+	sum = csum_fold(skb_checksum(skb, 0, len, skb->csum));
+	/* See comments in __skb_checksum_complete(). */
+	if (likely(!sum)) {
+		if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
+		    !skb->csum_complete_sw)
+			netdev_rx_csum_fault(skb->dev, skb);
+	}
+	if (!skb_shared(skb))
+		skb->csum_valid = !sum;
+	return sum;
+}
+EXPORT_SYMBOL(__skb_checksum_complete_head);
+
+/* This function assumes skb->csum already holds pseudo header's checksum,
+ * which has been changed from the hardware checksum, for example, by
+ * __skb_checksum_validate_complete(). And, the original skb->csum must
+ * have been validated unsuccessfully for CHECKSUM_COMPLETE case.
+ *
+ * It returns non-zero if the recomputed checksum is still invalid, otherwise
+ * zero. The new checksum is stored back into skb->csum unless the skb is
+ * shared.
+ */
+__sum16 __skb_checksum_complete(struct sk_buff *skb)
+{
+	__wsum csum;
+	__sum16 sum;
+
+	csum = skb_checksum(skb, 0, skb->len, 0);
+
+	sum = csum_fold(csum_add(skb->csum, csum));
+	/* This check is inverted, because we already knew the hardware
+	 * checksum is invalid before calling this function. So, if the
+	 * re-computed checksum is valid instead, then we have a mismatch
+	 * between the original skb->csum and skb_checksum(). This means either
+	 * the original hardware checksum is incorrect or we screw up skb->csum
+	 * when moving skb->data around.
+	 */
+	if (likely(!sum)) {
+		if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
+		    !skb->csum_complete_sw)
+			netdev_rx_csum_fault(skb->dev, skb);
+	}
+
+	if (!skb_shared(skb)) {
+		/* Save full packet checksum */
+		skb->csum = csum;
+		skb->ip_summed = CHECKSUM_COMPLETE;
+		skb->csum_complete_sw = 1;
+		skb->csum_valid = !sum;
+	}
+
+	return sum;
+}
+EXPORT_SYMBOL(__skb_checksum_complete);
+
+static __wsum warn_crc32c_csum_update(const void *buff, int len, __wsum sum)
+{
+	net_warn_ratelimited(
+		"%s: attempt to compute crc32c without libcrc32c.ko\n",
+		__func__);
+	return 0;
+}
+
+static __wsum warn_crc32c_csum_combine(__wsum csum, __wsum csum2,
+				       int offset, int len)
+{
+	net_warn_ratelimited(
+		"%s: attempt to compute crc32c without libcrc32c.ko\n",
+		__func__);
+	return 0;
+}
+
+static const struct skb_checksum_ops default_crc32c_ops = {
+	.update  = warn_crc32c_csum_update,
+	.combine = warn_crc32c_csum_combine,
+};
+
+const struct skb_checksum_ops *crc32c_csum_stub __read_mostly =
+	&default_crc32c_ops;
+EXPORT_SYMBOL(crc32c_csum_stub);
+
+ /**
+ *	skb_zerocopy_headlen - Calculate headroom needed for skb_zerocopy()
+ *	@from: source buffer
+ *
+ *	Calculates the amount of linear headroom needed in the 'to' skb passed
+ *	into skb_zerocopy().
+ */
+unsigned int
+skb_zerocopy_headlen(const struct sk_buff *from)
+{
+	unsigned int hlen = 0;
+
+	if (!from->head_frag ||
+	    skb_headlen(from) < L1_CACHE_BYTES ||
+	    skb_shinfo(from)->nr_frags >= MAX_SKB_FRAGS) {
+		hlen = skb_headlen(from);
+		if (!hlen)
+			hlen = from->len;
+	}
+
+	if (skb_has_frag_list(from))
+		hlen = from->len;
+
+	return hlen;
+}
+EXPORT_SYMBOL_GPL(skb_zerocopy_headlen);
+
+/**
+ *	skb_zerocopy - Zero copy skb to skb
+ *	@to: destination buffer
+ *	@from: source buffer
+ *	@len: number of bytes to copy from source buffer
+ *	@hlen: size of linear headroom in destination buffer
+ *
+ *	Copies up to `len` bytes from `from` to `to` by creating references
+ *	to the frags in the source buffer.
+ *
+ *	The `hlen` as calculated by skb_zerocopy_headlen() specifies the
+ *	headroom in the `to` buffer.
+ *
+ *	Return value:
+ *	0: everything is OK
+ *	-ENOMEM: couldn't orphan frags of @from due to lack of memory
+ *	-EFAULT: skb_copy_bits() found some problem with skb geometry
+ */
+int
+skb_zerocopy(struct sk_buff *to, struct sk_buff *from, int len, int hlen)
+{
+	int i, j = 0;
+	int plen = 0; /* length of skb->head fragment */
+	int ret;
+	struct page *page;
+	unsigned int offset;
+
+	BUG_ON(!from->head_frag && !hlen);
+
+	/* dont bother with small payloads */
+	if (len <= skb_tailroom(to))
+		return skb_copy_bits(from, 0, skb_put(to, len), len);
+
+	if (hlen) {
+		ret = skb_copy_bits(from, 0, skb_put(to, hlen), hlen);
+		if (unlikely(ret))
+			return ret;
+		len -= hlen;
+	} else {
+		plen = min_t(int, skb_headlen(from), len);
+		if (plen) {
+			page = virt_to_head_page(from->head);
+			offset = from->data - (unsigned char *)page_address(page);
+			__skb_fill_page_desc(to, 0, page, offset, plen);
+			get_page(page);
+			j = 1;
+			len -= plen;
+		}
+	}
+
+	skb_len_add(to, len + plen);
+
+	if (unlikely(skb_orphan_frags(from, GFP_ATOMIC))) {
+		skb_tx_error(from);
+		return -ENOMEM;
+	}
+	skb_zerocopy_clone(to, from, GFP_ATOMIC);
+
+	for (i = 0; i < skb_shinfo(from)->nr_frags; i++) {
+		int size;
+
+		if (!len)
+			break;
+		skb_shinfo(to)->frags[j] = skb_shinfo(from)->frags[i];
+		size = min_t(int, skb_frag_size(&skb_shinfo(to)->frags[j]),
+					len);
+		skb_frag_size_set(&skb_shinfo(to)->frags[j], size);
+		len -= size;
+		skb_frag_ref(to, j);
+		j++;
+	}
+	skb_shinfo(to)->nr_frags = j;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(skb_zerocopy);
+
+void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to)
+{
+	__wsum csum;
+	long csstart;
+
+	if (skb->ip_summed == CHECKSUM_PARTIAL)
+		csstart = skb_checksum_start_offset(skb);
+	else
+		csstart = skb_headlen(skb);
+
+	BUG_ON(csstart > skb_headlen(skb));
+
+	skb_copy_from_linear_data(skb, to, csstart);
+
+	csum = 0;
+	if (csstart != skb->len)
+		csum = skb_copy_and_csum_bits(skb, csstart, to + csstart,
+					      skb->len - csstart);
+
+	if (skb->ip_summed == CHECKSUM_PARTIAL) {
+		long csstuff = csstart + skb->csum_offset;
+
+		*((__sum16 *)(to + csstuff)) = csum_fold(csum);
+	}
+}
+EXPORT_SYMBOL(skb_copy_and_csum_dev);
+
+/**
+ *	skb_dequeue - remove from the head of the queue
+ *	@list: list to dequeue from
+ *
+ *	Remove the head of the list. The list lock is taken so the function
+ *	may be used safely with other locking list functions. The head item is
+ *	returned or %NULL if the list is empty.
+ */
+
+struct sk_buff *skb_dequeue(struct sk_buff_head *list)
+{
+	unsigned long flags;
+	struct sk_buff *result;
+
+	spin_lock_irqsave(&list->lock, flags);
+	result = __skb_dequeue(list);
+	spin_unlock_irqrestore(&list->lock, flags);
+	return result;
+}
+EXPORT_SYMBOL(skb_dequeue);
+
+/**
+ *	skb_dequeue_tail - remove from the tail of the queue
+ *	@list: list to dequeue from
+ *
+ *	Remove the tail of the list. The list lock is taken so the function
+ *	may be used safely with other locking list functions. The tail item is
+ *	returned or %NULL if the list is empty.
+ */
+struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list)
+{
+	unsigned long flags;
+	struct sk_buff *result;
+
+	spin_lock_irqsave(&list->lock, flags);
+	result = __skb_dequeue_tail(list);
+	spin_unlock_irqrestore(&list->lock, flags);
+	return result;
+}
+EXPORT_SYMBOL(skb_dequeue_tail);
+
+/**
+ *	skb_queue_purge - empty a list
+ *	@list: list to empty
+ *
+ *	Delete all buffers on an &sk_buff list. Each buffer is removed from
+ *	the list and one reference dropped. This function takes the list
+ *	lock and is atomic with respect to other list locking functions.
+ */
+void skb_queue_purge(struct sk_buff_head *list)
+{
+	struct sk_buff *skb;
+	while ((skb = skb_dequeue(list)) != NULL)
+		kfree_skb(skb);
+}
+EXPORT_SYMBOL(skb_queue_purge);
+
+/**
+ *	skb_rbtree_purge - empty a skb rbtree
+ *	@root: root of the rbtree to empty
+ *	Return value: the sum of truesizes of all purged skbs.
+ *
+ *	Delete all buffers on an &sk_buff rbtree. Each buffer is removed from
+ *	the list and one reference dropped. This function does not take
+ *	any lock. Synchronization should be handled by the caller (e.g., TCP
+ *	out-of-order queue is protected by the socket lock).
+ */
+unsigned int skb_rbtree_purge(struct rb_root *root)
+{
+	struct rb_node *p = rb_first(root);
+	unsigned int sum = 0;
+
+	while (p) {
+		struct sk_buff *skb = rb_entry(p, struct sk_buff, rbnode);
+
+		p = rb_next(p);
+		rb_erase(&skb->rbnode, root);
+		sum += skb->truesize;
+		kfree_skb(skb);
+	}
+	return sum;
+}
+
+/**
+ *	skb_queue_head - queue a buffer at the list head
+ *	@list: list to use
+ *	@newsk: buffer to queue
+ *
+ *	Queue a buffer at the start of the list. This function takes the
+ *	list lock and can be used safely with other locking &sk_buff functions
+ *	safely.
+ *
+ *	A buffer cannot be placed on two lists at the same time.
+ */
+void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&list->lock, flags);
+	__skb_queue_head(list, newsk);
+	spin_unlock_irqrestore(&list->lock, flags);
+}
+EXPORT_SYMBOL(skb_queue_head);
+
+/**
+ *	skb_queue_tail - queue a buffer at the list tail
+ *	@list: list to use
+ *	@newsk: buffer to queue
+ *
+ *	Queue a buffer at the tail of the list. This function takes the
+ *	list lock and can be used safely with other locking &sk_buff functions
+ *	safely.
+ *
+ *	A buffer cannot be placed on two lists at the same time.
+ */
+void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&list->lock, flags);
+	__skb_queue_tail(list, newsk);
+	spin_unlock_irqrestore(&list->lock, flags);
+}
+EXPORT_SYMBOL(skb_queue_tail);
+
+/**
+ *	skb_unlink	-	remove a buffer from a list
+ *	@skb: buffer to remove
+ *	@list: list to use
+ *
+ *	Remove a packet from a list. The list locks are taken and this
+ *	function is atomic with respect to other list locked calls
+ *
+ *	You must know what list the SKB is on.
+ */
+void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&list->lock, flags);
+	__skb_unlink(skb, list);
+	spin_unlock_irqrestore(&list->lock, flags);
+}
+EXPORT_SYMBOL(skb_unlink);
+
+/**
+ *	skb_append	-	append a buffer
+ *	@old: buffer to insert after
+ *	@newsk: buffer to insert
+ *	@list: list to use
+ *
+ *	Place a packet after a given packet in a list. The list locks are taken
+ *	and this function is atomic with respect to other list locked calls.
+ *	A buffer cannot be placed on two lists at the same time.
+ */
+void skb_append(struct sk_buff *old, struct sk_buff *newsk, struct sk_buff_head *list)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&list->lock, flags);
+	__skb_queue_after(list, old, newsk);
+	spin_unlock_irqrestore(&list->lock, flags);
+}
+EXPORT_SYMBOL(skb_append);
+
+static inline void skb_split_inside_header(struct sk_buff *skb,
+					   struct sk_buff* skb1,
+					   const u32 len, const int pos)
+{
+	int i;
+
+	skb_copy_from_linear_data_offset(skb, len, skb_put(skb1, pos - len),
+					 pos - len);
+	/* And move data appendix as is. */
+	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
+		skb_shinfo(skb1)->frags[i] = skb_shinfo(skb)->frags[i];
+
+	skb_shinfo(skb1)->nr_frags = skb_shinfo(skb)->nr_frags;
+	skb_shinfo(skb)->nr_frags  = 0;
+	skb1->data_len		   = skb->data_len;
+	skb1->len		   += skb1->data_len;
+	skb->data_len		   = 0;
+	skb->len		   = len;
+	skb_set_tail_pointer(skb, len);
+}
+
+static inline void skb_split_no_header(struct sk_buff *skb,
+				       struct sk_buff* skb1,
+				       const u32 len, int pos)
+{
+	int i, k = 0;
+	const int nfrags = skb_shinfo(skb)->nr_frags;
+
+	skb_shinfo(skb)->nr_frags = 0;
+	skb1->len		  = skb1->data_len = skb->len - len;
+	skb->len		  = len;
+	skb->data_len		  = len - pos;
+
+	for (i = 0; i < nfrags; i++) {
+		int size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
+
+		if (pos + size > len) {
+			skb_shinfo(skb1)->frags[k] = skb_shinfo(skb)->frags[i];
+
+			if (pos < len) {
+				/* Split frag.
+				 * We have two variants in this case:
+				 * 1. Move all the frag to the second
+				 *    part, if it is possible. F.e.
+				 *    this approach is mandatory for TUX,
+				 *    where splitting is expensive.
+				 * 2. Split is accurately. We make this.
+				 */
+				skb_frag_ref(skb, i);
+				skb_frag_off_add(&skb_shinfo(skb1)->frags[0], len - pos);
+				skb_frag_size_sub(&skb_shinfo(skb1)->frags[0], len - pos);
+				skb_frag_size_set(&skb_shinfo(skb)->frags[i], len - pos);
+				skb_shinfo(skb)->nr_frags++;
+			}
+			k++;
+		} else
+			skb_shinfo(skb)->nr_frags++;
+		pos += size;
+	}
+	skb_shinfo(skb1)->nr_frags = k;
+}
+
+/**
+ * skb_split - Split fragmented skb to two parts at length len.
+ * @skb: the buffer to split
+ * @skb1: the buffer to receive the second part
+ * @len: new length for skb
+ */
+void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len)
+{
+	int pos = skb_headlen(skb);
+	const int zc_flags = SKBFL_SHARED_FRAG | SKBFL_PURE_ZEROCOPY;
+
+	skb_zcopy_downgrade_managed(skb);
+
+	skb_shinfo(skb1)->flags |= skb_shinfo(skb)->flags & zc_flags;
+	skb_zerocopy_clone(skb1, skb, 0);
+	if (len < pos)	/* Split line is inside header. */
+		skb_split_inside_header(skb, skb1, len, pos);
+	else		/* Second chunk has no header, nothing to copy. */
+		skb_split_no_header(skb, skb1, len, pos);
+}
+EXPORT_SYMBOL(skb_split);
+
+/* Shifting from/to a cloned skb is a no-go.
+ *
+ * Caller cannot keep skb_shinfo related pointers past calling here!
+ */
+static int skb_prepare_for_shift(struct sk_buff *skb)
+{
+	return skb_unclone_keeptruesize(skb, GFP_ATOMIC);
+}
+
+/**
+ * skb_shift - Shifts paged data partially from skb to another
+ * @tgt: buffer into which tail data gets added
+ * @skb: buffer from which the paged data comes from
+ * @shiftlen: shift up to this many bytes
+ *
+ * Attempts to shift up to shiftlen worth of bytes, which may be less than
+ * the length of the skb, from skb to tgt. Returns number bytes shifted.
+ * It's up to caller to free skb if everything was shifted.
+ *
+ * If @tgt runs out of frags, the whole operation is aborted.
+ *
+ * Skb cannot include anything else but paged data while tgt is allowed
+ * to have non-paged data as well.
+ *
+ * TODO: full sized shift could be optimized but that would need
+ * specialized skb free'er to handle frags without up-to-date nr_frags.
+ */
+int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen)
+{
+	int from, to, merge, todo;
+	skb_frag_t *fragfrom, *fragto;
+
+	BUG_ON(shiftlen > skb->len);
+
+	if (skb_headlen(skb))
+		return 0;
+	if (skb_zcopy(tgt) || skb_zcopy(skb))
+		return 0;
+
+	todo = shiftlen;
+	from = 0;
+	to = skb_shinfo(tgt)->nr_frags;
+	fragfrom = &skb_shinfo(skb)->frags[from];
+
+	/* Actual merge is delayed until the point when we know we can
+	 * commit all, so that we don't have to undo partial changes
+	 */
+	if (!to ||
+	    !skb_can_coalesce(tgt, to, skb_frag_page(fragfrom),
+			      skb_frag_off(fragfrom))) {
+		merge = -1;
+	} else {
+		merge = to - 1;
+
+		todo -= skb_frag_size(fragfrom);
+		if (todo < 0) {
+			if (skb_prepare_for_shift(skb) ||
+			    skb_prepare_for_shift(tgt))
+				return 0;
+
+			/* All previous frag pointers might be stale! */
+			fragfrom = &skb_shinfo(skb)->frags[from];
+			fragto = &skb_shinfo(tgt)->frags[merge];
+
+			skb_frag_size_add(fragto, shiftlen);
+			skb_frag_size_sub(fragfrom, shiftlen);
+			skb_frag_off_add(fragfrom, shiftlen);
+
+			goto onlymerged;
+		}
+
+		from++;
+	}
+
+	/* Skip full, not-fitting skb to avoid expensive operations */
+	if ((shiftlen == skb->len) &&
+	    (skb_shinfo(skb)->nr_frags - from) > (MAX_SKB_FRAGS - to))
+		return 0;
+
+	if (skb_prepare_for_shift(skb) || skb_prepare_for_shift(tgt))
+		return 0;
+
+	while ((todo > 0) && (from < skb_shinfo(skb)->nr_frags)) {
+		if (to == MAX_SKB_FRAGS)
+			return 0;
+
+		fragfrom = &skb_shinfo(skb)->frags[from];
+		fragto = &skb_shinfo(tgt)->frags[to];
+
+		if (todo >= skb_frag_size(fragfrom)) {
+			*fragto = *fragfrom;
+			todo -= skb_frag_size(fragfrom);
+			from++;
+			to++;
+
+		} else {
+			__skb_frag_ref(fragfrom);
+			skb_frag_page_copy(fragto, fragfrom);
+			skb_frag_off_copy(fragto, fragfrom);
+			skb_frag_size_set(fragto, todo);
+
+			skb_frag_off_add(fragfrom, todo);
+			skb_frag_size_sub(fragfrom, todo);
+			todo = 0;
+
+			to++;
+			break;
+		}
+	}
+
+	/* Ready to "commit" this state change to tgt */
+	skb_shinfo(tgt)->nr_frags = to;
+
+	if (merge >= 0) {
+		fragfrom = &skb_shinfo(skb)->frags[0];
+		fragto = &skb_shinfo(tgt)->frags[merge];
+
+		skb_frag_size_add(fragto, skb_frag_size(fragfrom));
+		__skb_frag_unref(fragfrom, skb->pp_recycle);
+	}
+
+	/* Reposition in the original skb */
+	to = 0;
+	while (from < skb_shinfo(skb)->nr_frags)
+		skb_shinfo(skb)->frags[to++] = skb_shinfo(skb)->frags[from++];
+	skb_shinfo(skb)->nr_frags = to;
+
+	BUG_ON(todo > 0 && !skb_shinfo(skb)->nr_frags);
+
+onlymerged:
+	/* Most likely the tgt won't ever need its checksum anymore, skb on
+	 * the other hand might need it if it needs to be resent
+	 */
+	tgt->ip_summed = CHECKSUM_PARTIAL;
+	skb->ip_summed = CHECKSUM_PARTIAL;
+
+	skb_len_add(skb, -shiftlen);
+	skb_len_add(tgt, shiftlen);
+
+	return shiftlen;
+}
+
+/**
+ * skb_prepare_seq_read - Prepare a sequential read of skb data
+ * @skb: the buffer to read
+ * @from: lower offset of data to be read
+ * @to: upper offset of data to be read
+ * @st: state variable
+ *
+ * Initializes the specified state variable. Must be called before
+ * invoking skb_seq_read() for the first time.
+ */
+void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
+			  unsigned int to, struct skb_seq_state *st)
+{
+	st->lower_offset = from;
+	st->upper_offset = to;
+	st->root_skb = st->cur_skb = skb;
+	st->frag_idx = st->stepped_offset = 0;
+	st->frag_data = NULL;
+	st->frag_off = 0;
+}
+EXPORT_SYMBOL(skb_prepare_seq_read);
+
+/**
+ * skb_seq_read - Sequentially read skb data
+ * @consumed: number of bytes consumed by the caller so far
+ * @data: destination pointer for data to be returned
+ * @st: state variable
+ *
+ * Reads a block of skb data at @consumed relative to the
+ * lower offset specified to skb_prepare_seq_read(). Assigns
+ * the head of the data block to @data and returns the length
+ * of the block or 0 if the end of the skb data or the upper
+ * offset has been reached.
+ *
+ * The caller is not required to consume all of the data
+ * returned, i.e. @consumed is typically set to the number
+ * of bytes already consumed and the next call to
+ * skb_seq_read() will return the remaining part of the block.
+ *
+ * Note 1: The size of each block of data returned can be arbitrary,
+ *       this limitation is the cost for zerocopy sequential
+ *       reads of potentially non linear data.
+ *
+ * Note 2: Fragment lists within fragments are not implemented
+ *       at the moment, state->root_skb could be replaced with
+ *       a stack for this purpose.
+ */
+unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
+			  struct skb_seq_state *st)
+{
+	unsigned int block_limit, abs_offset = consumed + st->lower_offset;
+	skb_frag_t *frag;
+
+	if (unlikely(abs_offset >= st->upper_offset)) {
+		if (st->frag_data) {
+			kunmap_atomic(st->frag_data);
+			st->frag_data = NULL;
+		}
+		return 0;
+	}
+
+next_skb:
+	block_limit = skb_headlen(st->cur_skb) + st->stepped_offset;
+
+	if (abs_offset < block_limit && !st->frag_data) {
+		*data = st->cur_skb->data + (abs_offset - st->stepped_offset);
+		return block_limit - abs_offset;
+	}
+
+	if (st->frag_idx == 0 && !st->frag_data)
+		st->stepped_offset += skb_headlen(st->cur_skb);
+
+	while (st->frag_idx < skb_shinfo(st->cur_skb)->nr_frags) {
+		unsigned int pg_idx, pg_off, pg_sz;
+
+		frag = &skb_shinfo(st->cur_skb)->frags[st->frag_idx];
+
+		pg_idx = 0;
+		pg_off = skb_frag_off(frag);
+		pg_sz = skb_frag_size(frag);
+
+		if (skb_frag_must_loop(skb_frag_page(frag))) {
+			pg_idx = (pg_off + st->frag_off) >> PAGE_SHIFT;
+			pg_off = offset_in_page(pg_off + st->frag_off);
+			pg_sz = min_t(unsigned int, pg_sz - st->frag_off,
+						    PAGE_SIZE - pg_off);
+		}
+
+		block_limit = pg_sz + st->stepped_offset;
+		if (abs_offset < block_limit) {
+			if (!st->frag_data)
+				st->frag_data = kmap_atomic(skb_frag_page(frag) + pg_idx);
+
+			*data = (u8 *)st->frag_data + pg_off +
+				(abs_offset - st->stepped_offset);
+
+			return block_limit - abs_offset;
+		}
+
+		if (st->frag_data) {
+			kunmap_atomic(st->frag_data);
+			st->frag_data = NULL;
+		}
+
+		st->stepped_offset += pg_sz;
+		st->frag_off += pg_sz;
+		if (st->frag_off == skb_frag_size(frag)) {
+			st->frag_off = 0;
+			st->frag_idx++;
+		}
+	}
+
+	if (st->frag_data) {
+		kunmap_atomic(st->frag_data);
+		st->frag_data = NULL;
+	}
+
+	if (st->root_skb == st->cur_skb && skb_has_frag_list(st->root_skb)) {
+		st->cur_skb = skb_shinfo(st->root_skb)->frag_list;
+		st->frag_idx = 0;
+		goto next_skb;
+	} else if (st->cur_skb->next) {
+		st->cur_skb = st->cur_skb->next;
+		st->frag_idx = 0;
+		goto next_skb;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(skb_seq_read);
+
+/**
+ * skb_abort_seq_read - Abort a sequential read of skb data
+ * @st: state variable
+ *
+ * Must be called if skb_seq_read() was not called until it
+ * returned 0.
+ */
+void skb_abort_seq_read(struct skb_seq_state *st)
+{
+	if (st->frag_data)
+		kunmap_atomic(st->frag_data);
+}
+EXPORT_SYMBOL(skb_abort_seq_read);
+
+#define TS_SKB_CB(state)	((struct skb_seq_state *) &((state)->cb))
+
+static unsigned int skb_ts_get_next_block(unsigned int offset, const u8 **text,
+					  struct ts_config *conf,
+					  struct ts_state *state)
+{
+	return skb_seq_read(offset, text, TS_SKB_CB(state));
+}
+
+static void skb_ts_finish(struct ts_config *conf, struct ts_state *state)
+{
+	skb_abort_seq_read(TS_SKB_CB(state));
+}
+
+/**
+ * skb_find_text - Find a text pattern in skb data
+ * @skb: the buffer to look in
+ * @from: search offset
+ * @to: search limit
+ * @config: textsearch configuration
+ *
+ * Finds a pattern in the skb data according to the specified
+ * textsearch configuration. Use textsearch_next() to retrieve
+ * subsequent occurrences of the pattern. Returns the offset
+ * to the first occurrence or UINT_MAX if no match was found.
+ */
+unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
+			   unsigned int to, struct ts_config *config)
+{
+	unsigned int patlen = config->ops->get_pattern_len(config);
+	struct ts_state state;
+	unsigned int ret;
+
+	BUILD_BUG_ON(sizeof(struct skb_seq_state) > sizeof(state.cb));
+
+	config->get_next_block = skb_ts_get_next_block;
+	config->finish = skb_ts_finish;
+
+	skb_prepare_seq_read(skb, from, to, TS_SKB_CB(&state));
+
+	ret = textsearch_find(config, &state);
+	return (ret + patlen <= to - from ? ret : UINT_MAX);
+}
+EXPORT_SYMBOL(skb_find_text);
+
+int skb_append_pagefrags(struct sk_buff *skb, struct page *page,
+			 int offset, size_t size)
+{
+	int i = skb_shinfo(skb)->nr_frags;
+
+	if (skb_can_coalesce(skb, i, page, offset)) {
+		skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], size);
+	} else if (i < MAX_SKB_FRAGS) {
+		skb_zcopy_downgrade_managed(skb);
+		get_page(page);
+		skb_fill_page_desc_noacc(skb, i, page, offset, size);
+	} else {
+		return -EMSGSIZE;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(skb_append_pagefrags);
+
+/**
+ *	skb_pull_rcsum - pull skb and update receive checksum
+ *	@skb: buffer to update
+ *	@len: length of data pulled
+ *
+ *	This function performs an skb_pull on the packet and updates
+ *	the CHECKSUM_COMPLETE checksum.  It should be used on
+ *	receive path processing instead of skb_pull unless you know
+ *	that the checksum difference is zero (e.g., a valid IP header)
+ *	or you are setting ip_summed to CHECKSUM_NONE.
+ */
+void *skb_pull_rcsum(struct sk_buff *skb, unsigned int len)
+{
+	unsigned char *data = skb->data;
+
+	BUG_ON(len > skb->len);
+	__skb_pull(skb, len);
+	skb_postpull_rcsum(skb, data, len);
+	return skb->data;
+}
+EXPORT_SYMBOL_GPL(skb_pull_rcsum);
+
+static inline skb_frag_t skb_head_frag_to_page_desc(struct sk_buff *frag_skb)
+{
+	skb_frag_t head_frag;
+	struct page *page;
+
+	page = virt_to_head_page(frag_skb->head);
+	__skb_frag_set_page(&head_frag, page);
+	skb_frag_off_set(&head_frag, frag_skb->data -
+			 (unsigned char *)page_address(page));
+	skb_frag_size_set(&head_frag, skb_headlen(frag_skb));
+	return head_frag;
+}
+
+struct sk_buff *skb_segment_list(struct sk_buff *skb,
+				 netdev_features_t features,
+				 unsigned int offset)
+{
+	struct sk_buff *list_skb = skb_shinfo(skb)->frag_list;
+	unsigned int tnl_hlen = skb_tnl_header_len(skb);
+	unsigned int delta_truesize = 0;
+	unsigned int delta_len = 0;
+	struct sk_buff *tail = NULL;
+	struct sk_buff *nskb, *tmp;
+	int len_diff, err;
+
+	skb_push(skb, -skb_network_offset(skb) + offset);
+
+	/* Ensure the head is writeable before touching the shared info */
+	err = skb_unclone(skb, GFP_ATOMIC);
+	if (err)
+		goto err_linearize;
+
+	skb_shinfo(skb)->frag_list = NULL;
+
+	while (list_skb) {
+		nskb = list_skb;
+		list_skb = list_skb->next;
+
+		err = 0;
+		delta_truesize += nskb->truesize;
+		if (skb_shared(nskb)) {
+			tmp = skb_clone(nskb, GFP_ATOMIC);
+			if (tmp) {
+				consume_skb(nskb);
+				nskb = tmp;
+				err = skb_unclone(nskb, GFP_ATOMIC);
+			} else {
+				err = -ENOMEM;
+			}
+		}
+
+		if (!tail)
+			skb->next = nskb;
+		else
+			tail->next = nskb;
+
+		if (unlikely(err)) {
+			nskb->next = list_skb;
+			goto err_linearize;
+		}
+
+		tail = nskb;
+
+		delta_len += nskb->len;
+
+		skb_push(nskb, -skb_network_offset(nskb) + offset);
+
+		skb_release_head_state(nskb);
+		len_diff = skb_network_header_len(nskb) - skb_network_header_len(skb);
+		__copy_skb_header(nskb, skb);
+
+		skb_headers_offset_update(nskb, skb_headroom(nskb) - skb_headroom(skb));
+		nskb->transport_header += len_diff;
+		skb_copy_from_linear_data_offset(skb, -tnl_hlen,
+						 nskb->data - tnl_hlen,
+						 offset + tnl_hlen);
+
+		if (skb_needs_linearize(nskb, features) &&
+		    __skb_linearize(nskb))
+			goto err_linearize;
+	}
+
+	skb->truesize = skb->truesize - delta_truesize;
+	skb->data_len = skb->data_len - delta_len;
+	skb->len = skb->len - delta_len;
+
+	skb_gso_reset(skb);
+
+	skb->prev = tail;
+
+	if (skb_needs_linearize(skb, features) &&
+	    __skb_linearize(skb))
+		goto err_linearize;
+
+	skb_get(skb);
+
+	return skb;
+
+err_linearize:
+	kfree_skb_list(skb->next);
+	skb->next = NULL;
+	return ERR_PTR(-ENOMEM);
+}
+EXPORT_SYMBOL_GPL(skb_segment_list);
+
+/**
+ *	skb_segment - Perform protocol segmentation on skb.
+ *	@head_skb: buffer to segment
+ *	@features: features for the output path (see dev->features)
+ *
+ *	This function performs segmentation on the given skb.  It returns
+ *	a pointer to the first in a list of new skbs for the segments.
+ *	In case of error it returns ERR_PTR(err).
+ */
+struct sk_buff *skb_segment(struct sk_buff *head_skb,
+			    netdev_features_t features)
+{
+	struct sk_buff *segs = NULL;
+	struct sk_buff *tail = NULL;
+	struct sk_buff *list_skb = skb_shinfo(head_skb)->frag_list;
+	unsigned int mss = skb_shinfo(head_skb)->gso_size;
+	unsigned int doffset = head_skb->data - skb_mac_header(head_skb);
+	unsigned int offset = doffset;
+	unsigned int tnl_hlen = skb_tnl_header_len(head_skb);
+	unsigned int partial_segs = 0;
+	unsigned int headroom;
+	unsigned int len = head_skb->len;
+	struct sk_buff *frag_skb;
+	skb_frag_t *frag;
+	__be16 proto;
+	bool csum, sg;
+	int err = -ENOMEM;
+	int i = 0;
+	int nfrags, pos;
+
+	if ((skb_shinfo(head_skb)->gso_type & SKB_GSO_DODGY) &&
+	    mss != GSO_BY_FRAGS && mss != skb_headlen(head_skb)) {
+		struct sk_buff *check_skb;
+
+		for (check_skb = list_skb; check_skb; check_skb = check_skb->next) {
+			if (skb_headlen(check_skb) && !check_skb->head_frag) {
+				/* gso_size is untrusted, and we have a frag_list with
+				 * a linear non head_frag item.
+				 *
+				 * If head_skb's headlen does not fit requested gso_size,
+				 * it means that the frag_list members do NOT terminate
+				 * on exact gso_size boundaries. Hence we cannot perform
+				 * skb_frag_t page sharing. Therefore we must fallback to
+				 * copying the frag_list skbs; we do so by disabling SG.
+				 */
+				features &= ~NETIF_F_SG;
+				break;
+			}
+		}
+	}
+
+	__skb_push(head_skb, doffset);
+	proto = skb_network_protocol(head_skb, NULL);
+	if (unlikely(!proto))
+		return ERR_PTR(-EINVAL);
+
+	sg = !!(features & NETIF_F_SG);
+	csum = !!can_checksum_protocol(features, proto);
+
+	if (sg && csum && (mss != GSO_BY_FRAGS))  {
+		if (!(features & NETIF_F_GSO_PARTIAL)) {
+			struct sk_buff *iter;
+			unsigned int frag_len;
+
+			if (!list_skb ||
+			    !net_gso_ok(features, skb_shinfo(head_skb)->gso_type))
+				goto normal;
+
+			/* If we get here then all the required
+			 * GSO features except frag_list are supported.
+			 * Try to split the SKB to multiple GSO SKBs
+			 * with no frag_list.
+			 * Currently we can do that only when the buffers don't
+			 * have a linear part and all the buffers except
+			 * the last are of the same length.
+			 */
+			frag_len = list_skb->len;
+			skb_walk_frags(head_skb, iter) {
+				if (frag_len != iter->len && iter->next)
+					goto normal;
+				if (skb_headlen(iter) && !iter->head_frag)
+					goto normal;
+
+				len -= iter->len;
+			}
+
+			if (len != frag_len)
+				goto normal;
+		}
+
+		/* GSO partial only requires that we trim off any excess that
+		 * doesn't fit into an MSS sized block, so take care of that
+		 * now.
+		 */
+		partial_segs = len / mss;
+		if (partial_segs > 1)
+			mss *= partial_segs;
+		else
+			partial_segs = 0;
+	}
+
+normal:
+	headroom = skb_headroom(head_skb);
+	pos = skb_headlen(head_skb);
+
+	if (skb_orphan_frags(head_skb, GFP_ATOMIC))
+		return ERR_PTR(-ENOMEM);
+
+	nfrags = skb_shinfo(head_skb)->nr_frags;
+	frag = skb_shinfo(head_skb)->frags;
+	frag_skb = head_skb;
+
+	do {
+		struct sk_buff *nskb;
+		skb_frag_t *nskb_frag;
+		int hsize;
+		int size;
+
+		if (unlikely(mss == GSO_BY_FRAGS)) {
+			len = list_skb->len;
+		} else {
+			len = head_skb->len - offset;
+			if (len > mss)
+				len = mss;
+		}
+
+		hsize = skb_headlen(head_skb) - offset;
+
+		if (hsize <= 0 && i >= nfrags && skb_headlen(list_skb) &&
+		    (skb_headlen(list_skb) == len || sg)) {
+			BUG_ON(skb_headlen(list_skb) > len);
+
+			nskb = skb_clone(list_skb, GFP_ATOMIC);
+			if (unlikely(!nskb))
+				goto err;
+
+			i = 0;
+			nfrags = skb_shinfo(list_skb)->nr_frags;
+			frag = skb_shinfo(list_skb)->frags;
+			frag_skb = list_skb;
+			pos += skb_headlen(list_skb);
+
+			while (pos < offset + len) {
+				BUG_ON(i >= nfrags);
+
+				size = skb_frag_size(frag);
+				if (pos + size > offset + len)
+					break;
+
+				i++;
+				pos += size;
+				frag++;
+			}
+
+			list_skb = list_skb->next;
+
+			if (unlikely(pskb_trim(nskb, len))) {
+				kfree_skb(nskb);
+				goto err;
+			}
+
+			hsize = skb_end_offset(nskb);
+			if (skb_cow_head(nskb, doffset + headroom)) {
+				kfree_skb(nskb);
+				goto err;
+			}
+
+			nskb->truesize += skb_end_offset(nskb) - hsize;
+			skb_release_head_state(nskb);
+			__skb_push(nskb, doffset);
+		} else {
+			if (hsize < 0)
+				hsize = 0;
+			if (hsize > len || !sg)
+				hsize = len;
+
+			nskb = __alloc_skb(hsize + doffset + headroom,
+					   GFP_ATOMIC, skb_alloc_rx_flag(head_skb),
+					   NUMA_NO_NODE);
+
+			if (unlikely(!nskb))
+				goto err;
+
+			skb_reserve(nskb, headroom);
+			__skb_put(nskb, doffset);
+		}
+
+		if (segs)
+			tail->next = nskb;
+		else
+			segs = nskb;
+		tail = nskb;
+
+		__copy_skb_header(nskb, head_skb);
+
+		skb_headers_offset_update(nskb, skb_headroom(nskb) - headroom);
+		skb_reset_mac_len(nskb);
+
+		skb_copy_from_linear_data_offset(head_skb, -tnl_hlen,
+						 nskb->data - tnl_hlen,
+						 doffset + tnl_hlen);
+
+		if (nskb->len == len + doffset)
+			goto perform_csum_check;
+
+		if (!sg) {
+			if (!csum) {
+				if (!nskb->remcsum_offload)
+					nskb->ip_summed = CHECKSUM_NONE;
+				SKB_GSO_CB(nskb)->csum =
+					skb_copy_and_csum_bits(head_skb, offset,
+							       skb_put(nskb,
+								       len),
+							       len);
+				SKB_GSO_CB(nskb)->csum_start =
+					skb_headroom(nskb) + doffset;
+			} else {
+				if (skb_copy_bits(head_skb, offset, skb_put(nskb, len), len))
+					goto err;
+			}
+			continue;
+		}
+
+		nskb_frag = skb_shinfo(nskb)->frags;
+
+		skb_copy_from_linear_data_offset(head_skb, offset,
+						 skb_put(nskb, hsize), hsize);
+
+		skb_shinfo(nskb)->flags |= skb_shinfo(head_skb)->flags &
+					   SKBFL_SHARED_FRAG;
+
+		if (skb_zerocopy_clone(nskb, frag_skb, GFP_ATOMIC))
+			goto err;
+
+		while (pos < offset + len) {
+			if (i >= nfrags) {
+				if (skb_orphan_frags(list_skb, GFP_ATOMIC) ||
+				    skb_zerocopy_clone(nskb, list_skb,
+						       GFP_ATOMIC))
+					goto err;
+
+				i = 0;
+				nfrags = skb_shinfo(list_skb)->nr_frags;
+				frag = skb_shinfo(list_skb)->frags;
+				frag_skb = list_skb;
+				if (!skb_headlen(list_skb)) {
+					BUG_ON(!nfrags);
+				} else {
+					BUG_ON(!list_skb->head_frag);
+
+					/* to make room for head_frag. */
+					i--;
+					frag--;
+				}
+
+				list_skb = list_skb->next;
+			}
+
+			if (unlikely(skb_shinfo(nskb)->nr_frags >=
+				     MAX_SKB_FRAGS)) {
+				net_warn_ratelimited(
+					"skb_segment: too many frags: %u %u\n",
+					pos, mss);
+				err = -EINVAL;
+				goto err;
+			}
+
+			*nskb_frag = (i < 0) ? skb_head_frag_to_page_desc(frag_skb) : *frag;
+			__skb_frag_ref(nskb_frag);
+			size = skb_frag_size(nskb_frag);
+
+			if (pos < offset) {
+				skb_frag_off_add(nskb_frag, offset - pos);
+				skb_frag_size_sub(nskb_frag, offset - pos);
+			}
+
+			skb_shinfo(nskb)->nr_frags++;
+
+			if (pos + size <= offset + len) {
+				i++;
+				frag++;
+				pos += size;
+			} else {
+				skb_frag_size_sub(nskb_frag, pos + size - (offset + len));
+				goto skip_fraglist;
+			}
+
+			nskb_frag++;
+		}
+
+skip_fraglist:
+		nskb->data_len = len - hsize;
+		nskb->len += nskb->data_len;
+		nskb->truesize += nskb->data_len;
+
+perform_csum_check:
+		if (!csum) {
+			if (skb_has_shared_frag(nskb) &&
+			    __skb_linearize(nskb))
+				goto err;
+
+			if (!nskb->remcsum_offload)
+				nskb->ip_summed = CHECKSUM_NONE;
+			SKB_GSO_CB(nskb)->csum =
+				skb_checksum(nskb, doffset,
+					     nskb->len - doffset, 0);
+			SKB_GSO_CB(nskb)->csum_start =
+				skb_headroom(nskb) + doffset;
+		}
+	} while ((offset += len) < head_skb->len);
+
+	/* Some callers want to get the end of the list.
+	 * Put it in segs->prev to avoid walking the list.
+	 * (see validate_xmit_skb_list() for example)
+	 */
+	segs->prev = tail;
+
+	if (partial_segs) {
+		struct sk_buff *iter;
+		int type = skb_shinfo(head_skb)->gso_type;
+		unsigned short gso_size = skb_shinfo(head_skb)->gso_size;
+
+		/* Update type to add partial and then remove dodgy if set */
+		type |= (features & NETIF_F_GSO_PARTIAL) / NETIF_F_GSO_PARTIAL * SKB_GSO_PARTIAL;
+		type &= ~SKB_GSO_DODGY;
+
+		/* Update GSO info and prepare to start updating headers on
+		 * our way back down the stack of protocols.
+		 */
+		for (iter = segs; iter; iter = iter->next) {
+			skb_shinfo(iter)->gso_size = gso_size;
+			skb_shinfo(iter)->gso_segs = partial_segs;
+			skb_shinfo(iter)->gso_type = type;
+			SKB_GSO_CB(iter)->data_offset = skb_headroom(iter) + doffset;
+		}
+
+		if (tail->len - doffset <= gso_size)
+			skb_shinfo(tail)->gso_size = 0;
+		else if (tail != segs)
+			skb_shinfo(tail)->gso_segs = DIV_ROUND_UP(tail->len - doffset, gso_size);
+	}
+
+	/* Following permits correct backpressure, for protocols
+	 * using skb_set_owner_w().
+	 * Idea is to tranfert ownership from head_skb to last segment.
+	 */
+	if (head_skb->destructor == sock_wfree) {
+		swap(tail->truesize, head_skb->truesize);
+		swap(tail->destructor, head_skb->destructor);
+		swap(tail->sk, head_skb->sk);
+	}
+	return segs;
+
+err:
+	kfree_skb_list(segs);
+	return ERR_PTR(err);
+}
+EXPORT_SYMBOL_GPL(skb_segment);
+
+#ifdef CONFIG_SKB_EXTENSIONS
+#define SKB_EXT_ALIGN_VALUE	8
+#define SKB_EXT_CHUNKSIZEOF(x)	(ALIGN((sizeof(x)), SKB_EXT_ALIGN_VALUE) / SKB_EXT_ALIGN_VALUE)
+
+static const u8 skb_ext_type_len[] = {
+#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
+	[SKB_EXT_BRIDGE_NF] = SKB_EXT_CHUNKSIZEOF(struct nf_bridge_info),
+#endif
+#ifdef CONFIG_XFRM
+	[SKB_EXT_SEC_PATH] = SKB_EXT_CHUNKSIZEOF(struct sec_path),
+#endif
+#if IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
+	[TC_SKB_EXT] = SKB_EXT_CHUNKSIZEOF(struct tc_skb_ext),
+#endif
+#if IS_ENABLED(CONFIG_MPTCP)
+	[SKB_EXT_MPTCP] = SKB_EXT_CHUNKSIZEOF(struct mptcp_ext),
+#endif
+#if IS_ENABLED(CONFIG_MCTP_FLOWS)
+	[SKB_EXT_MCTP] = SKB_EXT_CHUNKSIZEOF(struct mctp_flow),
+#endif
+};
+
+static __always_inline unsigned int skb_ext_total_length(void)
+{
+	return SKB_EXT_CHUNKSIZEOF(struct skb_ext) +
+#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
+		skb_ext_type_len[SKB_EXT_BRIDGE_NF] +
+#endif
+#ifdef CONFIG_XFRM
+		skb_ext_type_len[SKB_EXT_SEC_PATH] +
+#endif
+#if IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
+		skb_ext_type_len[TC_SKB_EXT] +
+#endif
+#if IS_ENABLED(CONFIG_MPTCP)
+		skb_ext_type_len[SKB_EXT_MPTCP] +
+#endif
+#if IS_ENABLED(CONFIG_MCTP_FLOWS)
+		skb_ext_type_len[SKB_EXT_MCTP] +
+#endif
+		0;
+}
+
+static void skb_extensions_init(void)
+{
+	BUILD_BUG_ON(SKB_EXT_NUM >= 8);
+	BUILD_BUG_ON(skb_ext_total_length() > 255);
+
+	skbuff_ext_cache = kmem_cache_create("skbuff_ext_cache",
+					     SKB_EXT_ALIGN_VALUE * skb_ext_total_length(),
+					     0,
+					     SLAB_HWCACHE_ALIGN|SLAB_PANIC,
+					     NULL);
+}
+#else
+static void skb_extensions_init(void) {}
+#endif
+
+void __init skb_init(void)
+{
+	skbuff_head_cache = kmem_cache_create_usercopy("skbuff_head_cache",
+					      sizeof(struct sk_buff),
+					      0,
+					      SLAB_HWCACHE_ALIGN|SLAB_PANIC,
+					      offsetof(struct sk_buff, cb),
+					      sizeof_field(struct sk_buff, cb),
+					      NULL);
+	skbuff_fclone_cache = kmem_cache_create("skbuff_fclone_cache",
+						sizeof(struct sk_buff_fclones),
+						0,
+						SLAB_HWCACHE_ALIGN|SLAB_PANIC,
+						NULL);
+	skb_extensions_init();
+}
+
+static int
+__skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len,
+	       unsigned int recursion_level)
+{
+	int start = skb_headlen(skb);
+	int i, copy = start - offset;
+	struct sk_buff *frag_iter;
+	int elt = 0;
+
+	if (unlikely(recursion_level >= 24))
+		return -EMSGSIZE;
+
+	if (copy > 0) {
+		if (copy > len)
+			copy = len;
+		sg_set_buf(sg, skb->data + offset, copy);
+		elt++;
+		if ((len -= copy) == 0)
+			return elt;
+		offset += copy;
+	}
+
+	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+		int end;
+
+		WARN_ON(start > offset + len);
+
+		end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]);
+		if ((copy = end - offset) > 0) {
+			skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
+			if (unlikely(elt && sg_is_last(&sg[elt - 1])))
+				return -EMSGSIZE;
+
+			if (copy > len)
+				copy = len;
+			sg_set_page(&sg[elt], skb_frag_page(frag), copy,
+				    skb_frag_off(frag) + offset - start);
+			elt++;
+			if (!(len -= copy))
+				return elt;
+			offset += copy;
+		}
+		start = end;
+	}
+
+	skb_walk_frags(skb, frag_iter) {
+		int end, ret;
+
+		WARN_ON(start > offset + len);
+
+		end = start + frag_iter->len;
+		if ((copy = end - offset) > 0) {
+			if (unlikely(elt && sg_is_last(&sg[elt - 1])))
+				return -EMSGSIZE;
+
+			if (copy > len)
+				copy = len;
+			ret = __skb_to_sgvec(frag_iter, sg+elt, offset - start,
+					      copy, recursion_level + 1);
+			if (unlikely(ret < 0))
+				return ret;
+			elt += ret;
+			if ((len -= copy) == 0)
+				return elt;
+			offset += copy;
+		}
+		start = end;
+	}
+	BUG_ON(len);
+	return elt;
+}
+
+/**
+ *	skb_to_sgvec - Fill a scatter-gather list from a socket buffer
+ *	@skb: Socket buffer containing the buffers to be mapped
+ *	@sg: The scatter-gather list to map into
+ *	@offset: The offset into the buffer's contents to start mapping
+ *	@len: Length of buffer space to be mapped
+ *
+ *	Fill the specified scatter-gather list with mappings/pointers into a
+ *	region of the buffer space attached to a socket buffer. Returns either
+ *	the number of scatterlist items used, or -EMSGSIZE if the contents
+ *	could not fit.
+ */
+int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len)
+{
+	int nsg = __skb_to_sgvec(skb, sg, offset, len, 0);
+
+	if (nsg <= 0)
+		return nsg;
+
+	sg_mark_end(&sg[nsg - 1]);
+
+	return nsg;
+}
+EXPORT_SYMBOL_GPL(skb_to_sgvec);
+
+/* As compared with skb_to_sgvec, skb_to_sgvec_nomark only map skb to given
+ * sglist without mark the sg which contain last skb data as the end.
+ * So the caller can mannipulate sg list as will when padding new data after
+ * the first call without calling sg_unmark_end to expend sg list.
+ *
+ * Scenario to use skb_to_sgvec_nomark:
+ * 1. sg_init_table
+ * 2. skb_to_sgvec_nomark(payload1)
+ * 3. skb_to_sgvec_nomark(payload2)
+ *
+ * This is equivalent to:
+ * 1. sg_init_table
+ * 2. skb_to_sgvec(payload1)
+ * 3. sg_unmark_end
+ * 4. skb_to_sgvec(payload2)
+ *
+ * When mapping mutilple payload conditionally, skb_to_sgvec_nomark
+ * is more preferable.
+ */
+int skb_to_sgvec_nomark(struct sk_buff *skb, struct scatterlist *sg,
+			int offset, int len)
+{
+	return __skb_to_sgvec(skb, sg, offset, len, 0);
+}
+EXPORT_SYMBOL_GPL(skb_to_sgvec_nomark);
+
+
+
+/**
+ *	skb_cow_data - Check that a socket buffer's data buffers are writable
+ *	@skb: The socket buffer to check.
+ *	@tailbits: Amount of trailing space to be added
+ *	@trailer: Returned pointer to the skb where the @tailbits space begins
+ *
+ *	Make sure that the data buffers attached to a socket buffer are
+ *	writable. If they are not, private copies are made of the data buffers
+ *	and the socket buffer is set to use these instead.
+ *
+ *	If @tailbits is given, make sure that there is space to write @tailbits
+ *	bytes of data beyond current end of socket buffer.  @trailer will be
+ *	set to point to the skb in which this space begins.
+ *
+ *	The number of scatterlist elements required to completely map the
+ *	COW'd and extended socket buffer will be returned.
+ */
+int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer)
+{
+	int copyflag;
+	int elt;
+	struct sk_buff *skb1, **skb_p;
+
+	/* If skb is cloned or its head is paged, reallocate
+	 * head pulling out all the pages (pages are considered not writable
+	 * at the moment even if they are anonymous).
+	 */
+	if ((skb_cloned(skb) || skb_shinfo(skb)->nr_frags) &&
+	    !__pskb_pull_tail(skb, __skb_pagelen(skb)))
+		return -ENOMEM;
+
+	/* Easy case. Most of packets will go this way. */
+	if (!skb_has_frag_list(skb)) {
+		/* A little of trouble, not enough of space for trailer.
+		 * This should not happen, when stack is tuned to generate
+		 * good frames. OK, on miss we reallocate and reserve even more
+		 * space, 128 bytes is fair. */
+
+		if (skb_tailroom(skb) < tailbits &&
+		    pskb_expand_head(skb, 0, tailbits-skb_tailroom(skb)+128, GFP_ATOMIC))
+			return -ENOMEM;
+
+		/* Voila! */
+		*trailer = skb;
+		return 1;
+	}
+
+	/* Misery. We are in troubles, going to mincer fragments... */
+
+	elt = 1;
+	skb_p = &skb_shinfo(skb)->frag_list;
+	copyflag = 0;
+
+	while ((skb1 = *skb_p) != NULL) {
+		int ntail = 0;
+
+		/* The fragment is partially pulled by someone,
+		 * this can happen on input. Copy it and everything
+		 * after it. */
+
+		if (skb_shared(skb1))
+			copyflag = 1;
+
+		/* If the skb is the last, worry about trailer. */
+
+		if (skb1->next == NULL && tailbits) {
+			if (skb_shinfo(skb1)->nr_frags ||
+			    skb_has_frag_list(skb1) ||
+			    skb_tailroom(skb1) < tailbits)
+				ntail = tailbits + 128;
+		}
+
+		if (copyflag ||
+		    skb_cloned(skb1) ||
+		    ntail ||
+		    skb_shinfo(skb1)->nr_frags ||
+		    skb_has_frag_list(skb1)) {
+			struct sk_buff *skb2;
+
+			/* Fuck, we are miserable poor guys... */
+			if (ntail == 0)
+				skb2 = skb_copy(skb1, GFP_ATOMIC);
+			else
+				skb2 = skb_copy_expand(skb1,
+						       skb_headroom(skb1),
+						       ntail,
+						       GFP_ATOMIC);
+			if (unlikely(skb2 == NULL))
+				return -ENOMEM;
+
+			if (skb1->sk)
+				skb_set_owner_w(skb2, skb1->sk);
+
+			/* Looking around. Are we still alive?
+			 * OK, link new skb, drop old one */
+
+			skb2->next = skb1->next;
+			*skb_p = skb2;
+			kfree_skb(skb1);
+			skb1 = skb2;
+		}
+		elt++;
+		*trailer = skb1;
+		skb_p = &skb1->next;
+	}
+
+	return elt;
+}
+EXPORT_SYMBOL_GPL(skb_cow_data);
+
+static void sock_rmem_free(struct sk_buff *skb)
+{
+	struct sock *sk = skb->sk;
+
+	atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
+}
+
+static void skb_set_err_queue(struct sk_buff *skb)
+{
+	/* pkt_type of skbs received on local sockets is never PACKET_OUTGOING.
+	 * So, it is safe to (mis)use it to mark skbs on the error queue.
+	 */
+	skb->pkt_type = PACKET_OUTGOING;
+	BUILD_BUG_ON(PACKET_OUTGOING == 0);
+}
+
+/*
+ * Note: We dont mem charge error packets (no sk_forward_alloc changes)
+ */
+int sock_queue_err_skb(struct sock *sk, struct sk_buff *skb)
+{
+	if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
+	    (unsigned int)READ_ONCE(sk->sk_rcvbuf))
+		return -ENOMEM;
+
+	skb_orphan(skb);
+	skb->sk = sk;
+	skb->destructor = sock_rmem_free;
+	atomic_add(skb->truesize, &sk->sk_rmem_alloc);
+	skb_set_err_queue(skb);
+
+	/* before exiting rcu section, make sure dst is refcounted */
+	skb_dst_force(skb);
+
+	skb_queue_tail(&sk->sk_error_queue, skb);
+	if (!sock_flag(sk, SOCK_DEAD))
+		sk_error_report(sk);
+	return 0;
+}
+EXPORT_SYMBOL(sock_queue_err_skb);
+
+static bool is_icmp_err_skb(const struct sk_buff *skb)
+{
+	return skb && (SKB_EXT_ERR(skb)->ee.ee_origin == SO_EE_ORIGIN_ICMP ||
+		       SKB_EXT_ERR(skb)->ee.ee_origin == SO_EE_ORIGIN_ICMP6);
+}
+
+struct sk_buff *sock_dequeue_err_skb(struct sock *sk)
+{
+	struct sk_buff_head *q = &sk->sk_error_queue;
+	struct sk_buff *skb, *skb_next = NULL;
+	bool icmp_next = false;
+	unsigned long flags;
+
+	spin_lock_irqsave(&q->lock, flags);
+	skb = __skb_dequeue(q);
+	if (skb && (skb_next = skb_peek(q))) {
+		icmp_next = is_icmp_err_skb(skb_next);
+		if (icmp_next)
+			sk->sk_err = SKB_EXT_ERR(skb_next)->ee.ee_errno;
+	}
+	spin_unlock_irqrestore(&q->lock, flags);
+
+	if (is_icmp_err_skb(skb) && !icmp_next)
+		sk->sk_err = 0;
+
+	if (skb_next)
+		sk_error_report(sk);
+
+	return skb;
+}
+EXPORT_SYMBOL(sock_dequeue_err_skb);
+
+/**
+ * skb_clone_sk - create clone of skb, and take reference to socket
+ * @skb: the skb to clone
+ *
+ * This function creates a clone of a buffer that holds a reference on
+ * sk_refcnt.  Buffers created via this function are meant to be
+ * returned using sock_queue_err_skb, or free via kfree_skb.
+ *
+ * When passing buffers allocated with this function to sock_queue_err_skb
+ * it is necessary to wrap the call with sock_hold/sock_put in order to
+ * prevent the socket from being released prior to being enqueued on
+ * the sk_error_queue.
+ */
+struct sk_buff *skb_clone_sk(struct sk_buff *skb)
+{
+	struct sock *sk = skb->sk;
+	struct sk_buff *clone;
+
+	if (!sk || !refcount_inc_not_zero(&sk->sk_refcnt))
+		return NULL;
+
+	clone = skb_clone(skb, GFP_ATOMIC);
+	if (!clone) {
+		sock_put(sk);
+		return NULL;
+	}
+
+	clone->sk = sk;
+	clone->destructor = sock_efree;
+
+	return clone;
+}
+EXPORT_SYMBOL(skb_clone_sk);
+
+static void __skb_complete_tx_timestamp(struct sk_buff *skb,
+					struct sock *sk,
+					int tstype,
+					bool opt_stats)
+{
+	struct sock_exterr_skb *serr;
+	int err;
+
+	BUILD_BUG_ON(sizeof(struct sock_exterr_skb) > sizeof(skb->cb));
+
+	serr = SKB_EXT_ERR(skb);
+	memset(serr, 0, sizeof(*serr));
+	serr->ee.ee_errno = ENOMSG;
+	serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING;
+	serr->ee.ee_info = tstype;
+	serr->opt_stats = opt_stats;
+	serr->header.h4.iif = skb->dev ? skb->dev->ifindex : 0;
+	if (READ_ONCE(sk->sk_tsflags) & SOF_TIMESTAMPING_OPT_ID) {
+		serr->ee.ee_data = skb_shinfo(skb)->tskey;
+		if (sk_is_tcp(sk))
+			serr->ee.ee_data -= atomic_read(&sk->sk_tskey);
+	}
+
+	err = sock_queue_err_skb(sk, skb);
+
+	if (err)
+		kfree_skb(skb);
+}
+
+static bool skb_may_tx_timestamp(struct sock *sk, bool tsonly)
+{
+	bool ret;
+
+	if (likely(READ_ONCE(sysctl_tstamp_allow_data) || tsonly))
+		return true;
+
+	read_lock_bh(&sk->sk_callback_lock);
+	ret = sk->sk_socket && sk->sk_socket->file &&
+	      file_ns_capable(sk->sk_socket->file, &init_user_ns, CAP_NET_RAW);
+	read_unlock_bh(&sk->sk_callback_lock);
+	return ret;
+}
+
+void skb_complete_tx_timestamp(struct sk_buff *skb,
+			       struct skb_shared_hwtstamps *hwtstamps)
+{
+	struct sock *sk = skb->sk;
+
+	if (!skb_may_tx_timestamp(sk, false))
+		goto err;
+
+	/* Take a reference to prevent skb_orphan() from freeing the socket,
+	 * but only if the socket refcount is not zero.
+	 */
+	if (likely(refcount_inc_not_zero(&sk->sk_refcnt))) {
+		*skb_hwtstamps(skb) = *hwtstamps;
+		__skb_complete_tx_timestamp(skb, sk, SCM_TSTAMP_SND, false);
+		sock_put(sk);
+		return;
+	}
+
+err:
+	kfree_skb(skb);
+}
+EXPORT_SYMBOL_GPL(skb_complete_tx_timestamp);
+
+void __skb_tstamp_tx(struct sk_buff *orig_skb,
+		     const struct sk_buff *ack_skb,
+		     struct skb_shared_hwtstamps *hwtstamps,
+		     struct sock *sk, int tstype)
+{
+	struct sk_buff *skb;
+	bool tsonly, opt_stats = false;
+	u32 tsflags;
+
+	if (!sk)
+		return;
+
+	tsflags = READ_ONCE(sk->sk_tsflags);
+	if (!hwtstamps && !(tsflags & SOF_TIMESTAMPING_OPT_TX_SWHW) &&
+	    skb_shinfo(orig_skb)->tx_flags & SKBTX_IN_PROGRESS)
+		return;
+
+	tsonly = tsflags & SOF_TIMESTAMPING_OPT_TSONLY;
+	if (!skb_may_tx_timestamp(sk, tsonly))
+		return;
+
+	if (tsonly) {
+#ifdef CONFIG_INET
+		if ((tsflags & SOF_TIMESTAMPING_OPT_STATS) &&
+		    sk_is_tcp(sk)) {
+			skb = tcp_get_timestamping_opt_stats(sk, orig_skb,
+							     ack_skb);
+			opt_stats = true;
+		} else
+#endif
+			skb = alloc_skb(0, GFP_ATOMIC);
+	} else {
+		skb = skb_clone(orig_skb, GFP_ATOMIC);
+
+		if (skb_orphan_frags_rx(skb, GFP_ATOMIC)) {
+			kfree_skb(skb);
+			return;
+		}
+	}
+	if (!skb)
+		return;
+
+	if (tsonly) {
+		skb_shinfo(skb)->tx_flags |= skb_shinfo(orig_skb)->tx_flags &
+					     SKBTX_ANY_TSTAMP;
+		skb_shinfo(skb)->tskey = skb_shinfo(orig_skb)->tskey;
+	}
+
+	if (hwtstamps)
+		*skb_hwtstamps(skb) = *hwtstamps;
+	else
+		__net_timestamp(skb);
+
+	__skb_complete_tx_timestamp(skb, sk, tstype, opt_stats);
+}
+EXPORT_SYMBOL_GPL(__skb_tstamp_tx);
+
+void skb_tstamp_tx(struct sk_buff *orig_skb,
+		   struct skb_shared_hwtstamps *hwtstamps)
+{
+	return __skb_tstamp_tx(orig_skb, NULL, hwtstamps, orig_skb->sk,
+			       SCM_TSTAMP_SND);
+}
+EXPORT_SYMBOL_GPL(skb_tstamp_tx);
+
+void skb_complete_wifi_ack(struct sk_buff *skb, bool acked)
+{
+	struct sock *sk = skb->sk;
+	struct sock_exterr_skb *serr;
+	int err = 1;
+
+	skb->wifi_acked_valid = 1;
+	skb->wifi_acked = acked;
+
+	serr = SKB_EXT_ERR(skb);
+	memset(serr, 0, sizeof(*serr));
+	serr->ee.ee_errno = ENOMSG;
+	serr->ee.ee_origin = SO_EE_ORIGIN_TXSTATUS;
+
+	/* Take a reference to prevent skb_orphan() from freeing the socket,
+	 * but only if the socket refcount is not zero.
+	 */
+	if (likely(refcount_inc_not_zero(&sk->sk_refcnt))) {
+		err = sock_queue_err_skb(sk, skb);
+		sock_put(sk);
+	}
+	if (err)
+		kfree_skb(skb);
+}
+EXPORT_SYMBOL_GPL(skb_complete_wifi_ack);
+
+/**
+ * skb_partial_csum_set - set up and verify partial csum values for packet
+ * @skb: the skb to set
+ * @start: the number of bytes after skb->data to start checksumming.
+ * @off: the offset from start to place the checksum.
+ *
+ * For untrusted partially-checksummed packets, we need to make sure the values
+ * for skb->csum_start and skb->csum_offset are valid so we don't oops.
+ *
+ * This function checks and sets those values and skb->ip_summed: if this
+ * returns false you should drop the packet.
+ */
+bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off)
+{
+	u32 csum_end = (u32)start + (u32)off + sizeof(__sum16);
+	u32 csum_start = skb_headroom(skb) + (u32)start;
+
+	if (unlikely(csum_start >= U16_MAX || csum_end > skb_headlen(skb))) {
+		net_warn_ratelimited("bad partial csum: csum=%u/%u headroom=%u headlen=%u\n",
+				     start, off, skb_headroom(skb), skb_headlen(skb));
+		return false;
+	}
+	skb->ip_summed = CHECKSUM_PARTIAL;
+	skb->csum_start = csum_start;
+	skb->csum_offset = off;
+	skb->transport_header = csum_start;
+	return true;
+}
+EXPORT_SYMBOL_GPL(skb_partial_csum_set);
+
+static int skb_maybe_pull_tail(struct sk_buff *skb, unsigned int len,
+			       unsigned int max)
+{
+	if (skb_headlen(skb) >= len)
+		return 0;
+
+	/* If we need to pullup then pullup to the max, so we
+	 * won't need to do it again.
+	 */
+	if (max > skb->len)
+		max = skb->len;
+
+	if (__pskb_pull_tail(skb, max - skb_headlen(skb)) == NULL)
+		return -ENOMEM;
+
+	if (skb_headlen(skb) < len)
+		return -EPROTO;
+
+	return 0;
+}
+
+#define MAX_TCP_HDR_LEN (15 * 4)
+
+static __sum16 *skb_checksum_setup_ip(struct sk_buff *skb,
+				      typeof(IPPROTO_IP) proto,
+				      unsigned int off)
+{
+	int err;
+
+	switch (proto) {
+	case IPPROTO_TCP:
+		err = skb_maybe_pull_tail(skb, off + sizeof(struct tcphdr),
+					  off + MAX_TCP_HDR_LEN);
+		if (!err && !skb_partial_csum_set(skb, off,
+						  offsetof(struct tcphdr,
+							   check)))
+			err = -EPROTO;
+		return err ? ERR_PTR(err) : &tcp_hdr(skb)->check;
+
+	case IPPROTO_UDP:
+		err = skb_maybe_pull_tail(skb, off + sizeof(struct udphdr),
+					  off + sizeof(struct udphdr));
+		if (!err && !skb_partial_csum_set(skb, off,
+						  offsetof(struct udphdr,
+							   check)))
+			err = -EPROTO;
+		return err ? ERR_PTR(err) : &udp_hdr(skb)->check;
+	}
+
+	return ERR_PTR(-EPROTO);
+}
+
+/* This value should be large enough to cover a tagged ethernet header plus
+ * maximally sized IP and TCP or UDP headers.
+ */
+#define MAX_IP_HDR_LEN 128
+
+static int skb_checksum_setup_ipv4(struct sk_buff *skb, bool recalculate)
+{
+	unsigned int off;
+	bool fragment;
+	__sum16 *csum;
+	int err;
+
+	fragment = false;
+
+	err = skb_maybe_pull_tail(skb,
+				  sizeof(struct iphdr),
+				  MAX_IP_HDR_LEN);
+	if (err < 0)
+		goto out;
+
+	if (ip_is_fragment(ip_hdr(skb)))
+		fragment = true;
+
+	off = ip_hdrlen(skb);
+
+	err = -EPROTO;
+
+	if (fragment)
+		goto out;
+
+	csum = skb_checksum_setup_ip(skb, ip_hdr(skb)->protocol, off);
+	if (IS_ERR(csum))
+		return PTR_ERR(csum);
+
+	if (recalculate)
+		*csum = ~csum_tcpudp_magic(ip_hdr(skb)->saddr,
+					   ip_hdr(skb)->daddr,
+					   skb->len - off,
+					   ip_hdr(skb)->protocol, 0);
+	err = 0;
+
+out:
+	return err;
+}
+
+/* This value should be large enough to cover a tagged ethernet header plus
+ * an IPv6 header, all options, and a maximal TCP or UDP header.
+ */
+#define MAX_IPV6_HDR_LEN 256
+
+#define OPT_HDR(type, skb, off) \
+	(type *)(skb_network_header(skb) + (off))
+
+static int skb_checksum_setup_ipv6(struct sk_buff *skb, bool recalculate)
+{
+	int err;
+	u8 nexthdr;
+	unsigned int off;
+	unsigned int len;
+	bool fragment;
+	bool done;
+	__sum16 *csum;
+
+	fragment = false;
+	done = false;
+
+	off = sizeof(struct ipv6hdr);
+
+	err = skb_maybe_pull_tail(skb, off, MAX_IPV6_HDR_LEN);
+	if (err < 0)
+		goto out;
+
+	nexthdr = ipv6_hdr(skb)->nexthdr;
+
+	len = sizeof(struct ipv6hdr) + ntohs(ipv6_hdr(skb)->payload_len);
+	while (off <= len && !done) {
+		switch (nexthdr) {
+		case IPPROTO_DSTOPTS:
+		case IPPROTO_HOPOPTS:
+		case IPPROTO_ROUTING: {
+			struct ipv6_opt_hdr *hp;
+
+			err = skb_maybe_pull_tail(skb,
+						  off +
+						  sizeof(struct ipv6_opt_hdr),
+						  MAX_IPV6_HDR_LEN);
+			if (err < 0)
+				goto out;
+
+			hp = OPT_HDR(struct ipv6_opt_hdr, skb, off);
+			nexthdr = hp->nexthdr;
+			off += ipv6_optlen(hp);
+			break;
+		}
+		case IPPROTO_AH: {
+			struct ip_auth_hdr *hp;
+
+			err = skb_maybe_pull_tail(skb,
+						  off +
+						  sizeof(struct ip_auth_hdr),
+						  MAX_IPV6_HDR_LEN);
+			if (err < 0)
+				goto out;
+
+			hp = OPT_HDR(struct ip_auth_hdr, skb, off);
+			nexthdr = hp->nexthdr;
+			off += ipv6_authlen(hp);
+			break;
+		}
+		case IPPROTO_FRAGMENT: {
+			struct frag_hdr *hp;
+
+			err = skb_maybe_pull_tail(skb,
+						  off +
+						  sizeof(struct frag_hdr),
+						  MAX_IPV6_HDR_LEN);
+			if (err < 0)
+				goto out;
+
+			hp = OPT_HDR(struct frag_hdr, skb, off);
+
+			if (hp->frag_off & htons(IP6_OFFSET | IP6_MF))
+				fragment = true;
+
+			nexthdr = hp->nexthdr;
+			off += sizeof(struct frag_hdr);
+			break;
+		}
+		default:
+			done = true;
+			break;
+		}
+	}
+
+	err = -EPROTO;
+
+	if (!done || fragment)
+		goto out;
+
+	csum = skb_checksum_setup_ip(skb, nexthdr, off);
+	if (IS_ERR(csum))
+		return PTR_ERR(csum);
+
+	if (recalculate)
+		*csum = ~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
+					 &ipv6_hdr(skb)->daddr,
+					 skb->len - off, nexthdr, 0);
+	err = 0;
+
+out:
+	return err;
+}
+
+/**
+ * skb_checksum_setup - set up partial checksum offset
+ * @skb: the skb to set up
+ * @recalculate: if true the pseudo-header checksum will be recalculated
+ */
+int skb_checksum_setup(struct sk_buff *skb, bool recalculate)
+{
+	int err;
+
+	switch (skb->protocol) {
+	case htons(ETH_P_IP):
+		err = skb_checksum_setup_ipv4(skb, recalculate);
+		break;
+
+	case htons(ETH_P_IPV6):
+		err = skb_checksum_setup_ipv6(skb, recalculate);
+		break;
+
+	default:
+		err = -EPROTO;
+		break;
+	}
+
+	return err;
+}
+EXPORT_SYMBOL(skb_checksum_setup);
+
+/**
+ * skb_checksum_maybe_trim - maybe trims the given skb
+ * @skb: the skb to check
+ * @transport_len: the data length beyond the network header
+ *
+ * Checks whether the given skb has data beyond the given transport length.
+ * If so, returns a cloned skb trimmed to this transport length.
+ * Otherwise returns the provided skb. Returns NULL in error cases
+ * (e.g. transport_len exceeds skb length or out-of-memory).
+ *
+ * Caller needs to set the skb transport header and free any returned skb if it
+ * differs from the provided skb.
+ */
+static struct sk_buff *skb_checksum_maybe_trim(struct sk_buff *skb,
+					       unsigned int transport_len)
+{
+	struct sk_buff *skb_chk;
+	unsigned int len = skb_transport_offset(skb) + transport_len;
+	int ret;
+
+	if (skb->len < len)
+		return NULL;
+	else if (skb->len == len)
+		return skb;
+
+	skb_chk = skb_clone(skb, GFP_ATOMIC);
+	if (!skb_chk)
+		return NULL;
+
+	ret = pskb_trim_rcsum(skb_chk, len);
+	if (ret) {
+		kfree_skb(skb_chk);
+		return NULL;
+	}
+
+	return skb_chk;
+}
+
+/**
+ * skb_checksum_trimmed - validate checksum of an skb
+ * @skb: the skb to check
+ * @transport_len: the data length beyond the network header
+ * @skb_chkf: checksum function to use
+ *
+ * Applies the given checksum function skb_chkf to the provided skb.
+ * Returns a checked and maybe trimmed skb. Returns NULL on error.
+ *
+ * If the skb has data beyond the given transport length, then a
+ * trimmed & cloned skb is checked and returned.
+ *
+ * Caller needs to set the skb transport header and free any returned skb if it
+ * differs from the provided skb.
+ */
+struct sk_buff *skb_checksum_trimmed(struct sk_buff *skb,
+				     unsigned int transport_len,
+				     __sum16(*skb_chkf)(struct sk_buff *skb))
+{
+	struct sk_buff *skb_chk;
+	unsigned int offset = skb_transport_offset(skb);
+	__sum16 ret;
+
+	skb_chk = skb_checksum_maybe_trim(skb, transport_len);
+	if (!skb_chk)
+		goto err;
+
+	if (!pskb_may_pull(skb_chk, offset))
+		goto err;
+
+	skb_pull_rcsum(skb_chk, offset);
+	ret = skb_chkf(skb_chk);
+	skb_push_rcsum(skb_chk, offset);
+
+	if (ret)
+		goto err;
+
+	return skb_chk;
+
+err:
+	if (skb_chk && skb_chk != skb)
+		kfree_skb(skb_chk);
+
+	return NULL;
+
+}
+EXPORT_SYMBOL(skb_checksum_trimmed);
+
+void __skb_warn_lro_forwarding(const struct sk_buff *skb)
+{
+	net_warn_ratelimited("%s: received packets cannot be forwarded while LRO is enabled\n",
+			     skb->dev->name);
+}
+EXPORT_SYMBOL(__skb_warn_lro_forwarding);
+
+void kfree_skb_partial(struct sk_buff *skb, bool head_stolen)
+{
+	if (head_stolen) {
+		skb_release_head_state(skb);
+		kmem_cache_free(skbuff_head_cache, skb);
+	} else {
+		__kfree_skb(skb);
+	}
+}
+EXPORT_SYMBOL(kfree_skb_partial);
+
+/**
+ * skb_try_coalesce - try to merge skb to prior one
+ * @to: prior buffer
+ * @from: buffer to add
+ * @fragstolen: pointer to boolean
+ * @delta_truesize: how much more was allocated than was requested
+ */
+bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
+		      bool *fragstolen, int *delta_truesize)
+{
+	struct skb_shared_info *to_shinfo, *from_shinfo;
+	int i, delta, len = from->len;
+
+	*fragstolen = false;
+
+	if (skb_cloned(to))
+		return false;
+
+	/* In general, avoid mixing page_pool and non-page_pool allocated
+	 * pages within the same SKB. Additionally avoid dealing with clones
+	 * with page_pool pages, in case the SKB is using page_pool fragment
+	 * references (PP_FLAG_PAGE_FRAG). Since we only take full page
+	 * references for cloned SKBs at the moment that would result in
+	 * inconsistent reference counts.
+	 * In theory we could take full references if @from is cloned and
+	 * !@to->pp_recycle but its tricky (due to potential race with
+	 * the clone disappearing) and rare, so not worth dealing with.
+	 */
+	if (to->pp_recycle != from->pp_recycle ||
+	    (from->pp_recycle && skb_cloned(from)))
+		return false;
+
+	if (len <= skb_tailroom(to)) {
+		if (len)
+			BUG_ON(skb_copy_bits(from, 0, skb_put(to, len), len));
+		*delta_truesize = 0;
+		return true;
+	}
+
+	to_shinfo = skb_shinfo(to);
+	from_shinfo = skb_shinfo(from);
+	if (to_shinfo->frag_list || from_shinfo->frag_list)
+		return false;
+	if (skb_zcopy(to) || skb_zcopy(from))
+		return false;
+
+	if (skb_headlen(from) != 0) {
+		struct page *page;
+		unsigned int offset;
+
+		if (to_shinfo->nr_frags +
+		    from_shinfo->nr_frags >= MAX_SKB_FRAGS)
+			return false;
+
+		if (skb_head_is_locked(from))
+			return false;
+
+		delta = from->truesize - SKB_DATA_ALIGN(sizeof(struct sk_buff));
+
+		page = virt_to_head_page(from->head);
+		offset = from->data - (unsigned char *)page_address(page);
+
+		skb_fill_page_desc(to, to_shinfo->nr_frags,
+				   page, offset, skb_headlen(from));
+		*fragstolen = true;
+	} else {
+		if (to_shinfo->nr_frags +
+		    from_shinfo->nr_frags > MAX_SKB_FRAGS)
+			return false;
+
+		delta = from->truesize - SKB_TRUESIZE(skb_end_offset(from));
+	}
+
+	WARN_ON_ONCE(delta < len);
+
+	memcpy(to_shinfo->frags + to_shinfo->nr_frags,
+	       from_shinfo->frags,
+	       from_shinfo->nr_frags * sizeof(skb_frag_t));
+	to_shinfo->nr_frags += from_shinfo->nr_frags;
+
+	if (!skb_cloned(from))
+		from_shinfo->nr_frags = 0;
+
+	/* if the skb is not cloned this does nothing
+	 * since we set nr_frags to 0.
+	 */
+	for (i = 0; i < from_shinfo->nr_frags; i++)
+		__skb_frag_ref(&from_shinfo->frags[i]);
+
+	to->truesize += delta;
+	to->len += len;
+	to->data_len += len;
+
+	*delta_truesize = delta;
+	return true;
+}
+EXPORT_SYMBOL(skb_try_coalesce);
+
+/**
+ * skb_scrub_packet - scrub an skb
+ *
+ * @skb: buffer to clean
+ * @xnet: packet is crossing netns
+ *
+ * skb_scrub_packet can be used after encapsulating or decapsulting a packet
+ * into/from a tunnel. Some information have to be cleared during these
+ * operations.
+ * skb_scrub_packet can also be used to clean a skb before injecting it in
+ * another namespace (@xnet == true). We have to clear all information in the
+ * skb that could impact namespace isolation.
+ */
+void skb_scrub_packet(struct sk_buff *skb, bool xnet)
+{
+	skb->pkt_type = PACKET_HOST;
+	skb->skb_iif = 0;
+	skb->ignore_df = 0;
+	skb_dst_drop(skb);
+	skb_ext_reset(skb);
+	nf_reset_ct(skb);
+	nf_reset_trace(skb);
+
+#ifdef CONFIG_NET_SWITCHDEV
+	skb->offload_fwd_mark = 0;
+	skb->offload_l3_fwd_mark = 0;
+#endif
+
+	if (!xnet)
+		return;
+
+	ipvs_reset(skb);
+	skb->mark = 0;
+	skb_clear_tstamp(skb);
+}
+EXPORT_SYMBOL_GPL(skb_scrub_packet);
+
+/**
+ * skb_gso_transport_seglen - Return length of individual segments of a gso packet
+ *
+ * @skb: GSO skb
+ *
+ * skb_gso_transport_seglen is used to determine the real size of the
+ * individual segments, including Layer4 headers (TCP/UDP).
+ *
+ * The MAC/L2 or network (IP, IPv6) headers are not accounted for.
+ */
+static unsigned int skb_gso_transport_seglen(const struct sk_buff *skb)
+{
+	const struct skb_shared_info *shinfo = skb_shinfo(skb);
+	unsigned int thlen = 0;
+
+	if (skb->encapsulation) {
+		thlen = skb_inner_transport_header(skb) -
+			skb_transport_header(skb);
+
+		if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6)))
+			thlen += inner_tcp_hdrlen(skb);
+	} else if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))) {
+		thlen = tcp_hdrlen(skb);
+	} else if (unlikely(skb_is_gso_sctp(skb))) {
+		thlen = sizeof(struct sctphdr);
+	} else if (shinfo->gso_type & SKB_GSO_UDP_L4) {
+		thlen = sizeof(struct udphdr);
+	}
+	/* UFO sets gso_size to the size of the fragmentation
+	 * payload, i.e. the size of the L4 (UDP) header is already
+	 * accounted for.
+	 */
+	return thlen + shinfo->gso_size;
+}
+
+/**
+ * skb_gso_network_seglen - Return length of individual segments of a gso packet
+ *
+ * @skb: GSO skb
+ *
+ * skb_gso_network_seglen is used to determine the real size of the
+ * individual segments, including Layer3 (IP, IPv6) and L4 headers (TCP/UDP).
+ *
+ * The MAC/L2 header is not accounted for.
+ */
+static unsigned int skb_gso_network_seglen(const struct sk_buff *skb)
+{
+	unsigned int hdr_len = skb_transport_header(skb) -
+			       skb_network_header(skb);
+
+	return hdr_len + skb_gso_transport_seglen(skb);
+}
+
+/**
+ * skb_gso_mac_seglen - Return length of individual segments of a gso packet
+ *
+ * @skb: GSO skb
+ *
+ * skb_gso_mac_seglen is used to determine the real size of the
+ * individual segments, including MAC/L2, Layer3 (IP, IPv6) and L4
+ * headers (TCP/UDP).
+ */
+static unsigned int skb_gso_mac_seglen(const struct sk_buff *skb)
+{
+	unsigned int hdr_len = skb_transport_header(skb) - skb_mac_header(skb);
+
+	return hdr_len + skb_gso_transport_seglen(skb);
+}
+
+/**
+ * skb_gso_size_check - check the skb size, considering GSO_BY_FRAGS
+ *
+ * There are a couple of instances where we have a GSO skb, and we
+ * want to determine what size it would be after it is segmented.
+ *
+ * We might want to check:
+ * -    L3+L4+payload size (e.g. IP forwarding)
+ * - L2+L3+L4+payload size (e.g. sanity check before passing to driver)
+ *
+ * This is a helper to do that correctly considering GSO_BY_FRAGS.
+ *
+ * @skb: GSO skb
+ *
+ * @seg_len: The segmented length (from skb_gso_*_seglen). In the
+ *           GSO_BY_FRAGS case this will be [header sizes + GSO_BY_FRAGS].
+ *
+ * @max_len: The maximum permissible length.
+ *
+ * Returns true if the segmented length <= max length.
+ */
+static inline bool skb_gso_size_check(const struct sk_buff *skb,
+				      unsigned int seg_len,
+				      unsigned int max_len) {
+	const struct skb_shared_info *shinfo = skb_shinfo(skb);
+	const struct sk_buff *iter;
+
+	if (shinfo->gso_size != GSO_BY_FRAGS)
+		return seg_len <= max_len;
+
+	/* Undo this so we can re-use header sizes */
+	seg_len -= GSO_BY_FRAGS;
+
+	skb_walk_frags(skb, iter) {
+		if (seg_len + skb_headlen(iter) > max_len)
+			return false;
+	}
+
+	return true;
+}
+
+/**
+ * skb_gso_validate_network_len - Will a split GSO skb fit into a given MTU?
+ *
+ * @skb: GSO skb
+ * @mtu: MTU to validate against
+ *
+ * skb_gso_validate_network_len validates if a given skb will fit a
+ * wanted MTU once split. It considers L3 headers, L4 headers, and the
+ * payload.
+ */
+bool skb_gso_validate_network_len(const struct sk_buff *skb, unsigned int mtu)
+{
+	return skb_gso_size_check(skb, skb_gso_network_seglen(skb), mtu);
+}
+EXPORT_SYMBOL_GPL(skb_gso_validate_network_len);
+
+/**
+ * skb_gso_validate_mac_len - Will a split GSO skb fit in a given length?
+ *
+ * @skb: GSO skb
+ * @len: length to validate against
+ *
+ * skb_gso_validate_mac_len validates if a given skb will fit a wanted
+ * length once split, including L2, L3 and L4 headers and the payload.
+ */
+bool skb_gso_validate_mac_len(const struct sk_buff *skb, unsigned int len)
+{
+	return skb_gso_size_check(skb, skb_gso_mac_seglen(skb), len);
+}
+EXPORT_SYMBOL_GPL(skb_gso_validate_mac_len);
+
+static struct sk_buff *skb_reorder_vlan_header(struct sk_buff *skb)
+{
+	int mac_len, meta_len;
+	void *meta;
+
+	if (skb_cow(skb, skb_headroom(skb)) < 0) {
+		kfree_skb(skb);
+		return NULL;
+	}
+
+	mac_len = skb->data - skb_mac_header(skb);
+	if (likely(mac_len > VLAN_HLEN + ETH_TLEN)) {
+		memmove(skb_mac_header(skb) + VLAN_HLEN, skb_mac_header(skb),
+			mac_len - VLAN_HLEN - ETH_TLEN);
+	}
+
+	meta_len = skb_metadata_len(skb);
+	if (meta_len) {
+		meta = skb_metadata_end(skb) - meta_len;
+		memmove(meta + VLAN_HLEN, meta, meta_len);
+	}
+
+	skb->mac_header += VLAN_HLEN;
+	return skb;
+}
+
+struct sk_buff *skb_vlan_untag(struct sk_buff *skb)
+{
+	struct vlan_hdr *vhdr;
+	u16 vlan_tci;
+
+	if (unlikely(skb_vlan_tag_present(skb))) {
+		/* vlan_tci is already set-up so leave this for another time */
+		return skb;
+	}
+
+	skb = skb_share_check(skb, GFP_ATOMIC);
+	if (unlikely(!skb))
+		goto err_free;
+	/* We may access the two bytes after vlan_hdr in vlan_set_encap_proto(). */
+	if (unlikely(!pskb_may_pull(skb, VLAN_HLEN + sizeof(unsigned short))))
+		goto err_free;
+
+	vhdr = (struct vlan_hdr *)skb->data;
+	vlan_tci = ntohs(vhdr->h_vlan_TCI);
+	__vlan_hwaccel_put_tag(skb, skb->protocol, vlan_tci);
+
+	skb_pull_rcsum(skb, VLAN_HLEN);
+	vlan_set_encap_proto(skb, vhdr);
+
+	skb = skb_reorder_vlan_header(skb);
+	if (unlikely(!skb))
+		goto err_free;
+
+	skb_reset_network_header(skb);
+	if (!skb_transport_header_was_set(skb))
+		skb_reset_transport_header(skb);
+	skb_reset_mac_len(skb);
+
+	return skb;
+
+err_free:
+	kfree_skb(skb);
+	return NULL;
+}
+EXPORT_SYMBOL(skb_vlan_untag);
+
+int skb_ensure_writable(struct sk_buff *skb, unsigned int write_len)
+{
+	if (!pskb_may_pull(skb, write_len))
+		return -ENOMEM;
+
+	if (!skb_cloned(skb) || skb_clone_writable(skb, write_len))
+		return 0;
+
+	return pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
+}
+EXPORT_SYMBOL(skb_ensure_writable);
+
+/* remove VLAN header from packet and update csum accordingly.
+ * expects a non skb_vlan_tag_present skb with a vlan tag payload
+ */
+int __skb_vlan_pop(struct sk_buff *skb, u16 *vlan_tci)
+{
+	struct vlan_hdr *vhdr;
+	int offset = skb->data - skb_mac_header(skb);
+	int err;
+
+	if (WARN_ONCE(offset,
+		      "__skb_vlan_pop got skb with skb->data not at mac header (offset %d)\n",
+		      offset)) {
+		return -EINVAL;
+	}
+
+	err = skb_ensure_writable(skb, VLAN_ETH_HLEN);
+	if (unlikely(err))
+		return err;
+
+	skb_postpull_rcsum(skb, skb->data + (2 * ETH_ALEN), VLAN_HLEN);
+
+	vhdr = (struct vlan_hdr *)(skb->data + ETH_HLEN);
+	*vlan_tci = ntohs(vhdr->h_vlan_TCI);
+
+	memmove(skb->data + VLAN_HLEN, skb->data, 2 * ETH_ALEN);
+	__skb_pull(skb, VLAN_HLEN);
+
+	vlan_set_encap_proto(skb, vhdr);
+	skb->mac_header += VLAN_HLEN;
+
+	if (skb_network_offset(skb) < ETH_HLEN)
+		skb_set_network_header(skb, ETH_HLEN);
+
+	skb_reset_mac_len(skb);
+
+	return err;
+}
+EXPORT_SYMBOL(__skb_vlan_pop);
+
+/* Pop a vlan tag either from hwaccel or from payload.
+ * Expects skb->data at mac header.
+ */
+int skb_vlan_pop(struct sk_buff *skb)
+{
+	u16 vlan_tci;
+	__be16 vlan_proto;
+	int err;
+
+	if (likely(skb_vlan_tag_present(skb))) {
+		__vlan_hwaccel_clear_tag(skb);
+	} else {
+		if (unlikely(!eth_type_vlan(skb->protocol)))
+			return 0;
+
+		err = __skb_vlan_pop(skb, &vlan_tci);
+		if (err)
+			return err;
+	}
+	/* move next vlan tag to hw accel tag */
+	if (likely(!eth_type_vlan(skb->protocol)))
+		return 0;
+
+	vlan_proto = skb->protocol;
+	err = __skb_vlan_pop(skb, &vlan_tci);
+	if (unlikely(err))
+		return err;
+
+	__vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
+	return 0;
+}
+EXPORT_SYMBOL(skb_vlan_pop);
+
+/* Push a vlan tag either into hwaccel or into payload (if hwaccel tag present).
+ * Expects skb->data at mac header.
+ */
+int skb_vlan_push(struct sk_buff *skb, __be16 vlan_proto, u16 vlan_tci)
+{
+	if (skb_vlan_tag_present(skb)) {
+		int offset = skb->data - skb_mac_header(skb);
+		int err;
+
+		if (WARN_ONCE(offset,
+			      "skb_vlan_push got skb with skb->data not at mac header (offset %d)\n",
+			      offset)) {
+			return -EINVAL;
+		}
+
+		err = __vlan_insert_tag(skb, skb->vlan_proto,
+					skb_vlan_tag_get(skb));
+		if (err)
+			return err;
+
+		skb->protocol = skb->vlan_proto;
+		skb->mac_len += VLAN_HLEN;
+
+		skb_postpush_rcsum(skb, skb->data + (2 * ETH_ALEN), VLAN_HLEN);
+	}
+	__vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
+	return 0;
+}
+EXPORT_SYMBOL(skb_vlan_push);
+
+/**
+ * skb_eth_pop() - Drop the Ethernet header at the head of a packet
+ *
+ * @skb: Socket buffer to modify
+ *
+ * Drop the Ethernet header of @skb.
+ *
+ * Expects that skb->data points to the mac header and that no VLAN tags are
+ * present.
+ *
+ * Returns 0 on success, -errno otherwise.
+ */
+int skb_eth_pop(struct sk_buff *skb)
+{
+	if (!pskb_may_pull(skb, ETH_HLEN) || skb_vlan_tagged(skb) ||
+	    skb_network_offset(skb) < ETH_HLEN)
+		return -EPROTO;
+
+	skb_pull_rcsum(skb, ETH_HLEN);
+	skb_reset_mac_header(skb);
+	skb_reset_mac_len(skb);
+
+	return 0;
+}
+EXPORT_SYMBOL(skb_eth_pop);
+
+/**
+ * skb_eth_push() - Add a new Ethernet header at the head of a packet
+ *
+ * @skb: Socket buffer to modify
+ * @dst: Destination MAC address of the new header
+ * @src: Source MAC address of the new header
+ *
+ * Prepend @skb with a new Ethernet header.
+ *
+ * Expects that skb->data points to the mac header, which must be empty.
+ *
+ * Returns 0 on success, -errno otherwise.
+ */
+int skb_eth_push(struct sk_buff *skb, const unsigned char *dst,
+		 const unsigned char *src)
+{
+	struct ethhdr *eth;
+	int err;
+
+	if (skb_network_offset(skb) || skb_vlan_tag_present(skb))
+		return -EPROTO;
+
+	err = skb_cow_head(skb, sizeof(*eth));
+	if (err < 0)
+		return err;
+
+	skb_push(skb, sizeof(*eth));
+	skb_reset_mac_header(skb);
+	skb_reset_mac_len(skb);
+
+	eth = eth_hdr(skb);
+	ether_addr_copy(eth->h_dest, dst);
+	ether_addr_copy(eth->h_source, src);
+	eth->h_proto = skb->protocol;
+
+	skb_postpush_rcsum(skb, eth, sizeof(*eth));
+
+	return 0;
+}
+EXPORT_SYMBOL(skb_eth_push);
+
+/* Update the ethertype of hdr and the skb csum value if required. */
+static void skb_mod_eth_type(struct sk_buff *skb, struct ethhdr *hdr,
+			     __be16 ethertype)
+{
+	if (skb->ip_summed == CHECKSUM_COMPLETE) {
+		__be16 diff[] = { ~hdr->h_proto, ethertype };
+
+		skb->csum = csum_partial((char *)diff, sizeof(diff), skb->csum);
+	}
+
+	hdr->h_proto = ethertype;
+}
+
+/**
+ * skb_mpls_push() - push a new MPLS header after mac_len bytes from start of
+ *                   the packet
+ *
+ * @skb: buffer
+ * @mpls_lse: MPLS label stack entry to push
+ * @mpls_proto: ethertype of the new MPLS header (expects 0x8847 or 0x8848)
+ * @mac_len: length of the MAC header
+ * @ethernet: flag to indicate if the resulting packet after skb_mpls_push is
+ *            ethernet
+ *
+ * Expects skb->data at mac header.
+ *
+ * Returns 0 on success, -errno otherwise.
+ */
+int skb_mpls_push(struct sk_buff *skb, __be32 mpls_lse, __be16 mpls_proto,
+		  int mac_len, bool ethernet)
+{
+	struct mpls_shim_hdr *lse;
+	int err;
+
+	if (unlikely(!eth_p_mpls(mpls_proto)))
+		return -EINVAL;
+
+	/* Networking stack does not allow simultaneous Tunnel and MPLS GSO. */
+	if (skb->encapsulation)
+		return -EINVAL;
+
+	err = skb_cow_head(skb, MPLS_HLEN);
+	if (unlikely(err))
+		return err;
+
+	if (!skb->inner_protocol) {
+		skb_set_inner_network_header(skb, skb_network_offset(skb));
+		skb_set_inner_protocol(skb, skb->protocol);
+	}
+
+	skb_push(skb, MPLS_HLEN);
+	memmove(skb_mac_header(skb) - MPLS_HLEN, skb_mac_header(skb),
+		mac_len);
+	skb_reset_mac_header(skb);
+	skb_set_network_header(skb, mac_len);
+	skb_reset_mac_len(skb);
+
+	lse = mpls_hdr(skb);
+	lse->label_stack_entry = mpls_lse;
+	skb_postpush_rcsum(skb, lse, MPLS_HLEN);
+
+	if (ethernet && mac_len >= ETH_HLEN)
+		skb_mod_eth_type(skb, eth_hdr(skb), mpls_proto);
+	skb->protocol = mpls_proto;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(skb_mpls_push);
+
+/**
+ * skb_mpls_pop() - pop the outermost MPLS header
+ *
+ * @skb: buffer
+ * @next_proto: ethertype of header after popped MPLS header
+ * @mac_len: length of the MAC header
+ * @ethernet: flag to indicate if the packet is ethernet
+ *
+ * Expects skb->data at mac header.
+ *
+ * Returns 0 on success, -errno otherwise.
+ */
+int skb_mpls_pop(struct sk_buff *skb, __be16 next_proto, int mac_len,
+		 bool ethernet)
+{
+	int err;
+
+	if (unlikely(!eth_p_mpls(skb->protocol)))
+		return 0;
+
+	err = skb_ensure_writable(skb, mac_len + MPLS_HLEN);
+	if (unlikely(err))
+		return err;
+
+	skb_postpull_rcsum(skb, mpls_hdr(skb), MPLS_HLEN);
+	memmove(skb_mac_header(skb) + MPLS_HLEN, skb_mac_header(skb),
+		mac_len);
+
+	__skb_pull(skb, MPLS_HLEN);
+	skb_reset_mac_header(skb);
+	skb_set_network_header(skb, mac_len);
+
+	if (ethernet && mac_len >= ETH_HLEN) {
+		struct ethhdr *hdr;
+
+		/* use mpls_hdr() to get ethertype to account for VLANs. */
+		hdr = (struct ethhdr *)((void *)mpls_hdr(skb) - ETH_HLEN);
+		skb_mod_eth_type(skb, hdr, next_proto);
+	}
+	skb->protocol = next_proto;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(skb_mpls_pop);
+
+/**
+ * skb_mpls_update_lse() - modify outermost MPLS header and update csum
+ *
+ * @skb: buffer
+ * @mpls_lse: new MPLS label stack entry to update to
+ *
+ * Expects skb->data at mac header.
+ *
+ * Returns 0 on success, -errno otherwise.
+ */
+int skb_mpls_update_lse(struct sk_buff *skb, __be32 mpls_lse)
+{
+	int err;
+
+	if (unlikely(!eth_p_mpls(skb->protocol)))
+		return -EINVAL;
+
+	err = skb_ensure_writable(skb, skb->mac_len + MPLS_HLEN);
+	if (unlikely(err))
+		return err;
+
+	if (skb->ip_summed == CHECKSUM_COMPLETE) {
+		__be32 diff[] = { ~mpls_hdr(skb)->label_stack_entry, mpls_lse };
+
+		skb->csum = csum_partial((char *)diff, sizeof(diff), skb->csum);
+	}
+
+	mpls_hdr(skb)->label_stack_entry = mpls_lse;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(skb_mpls_update_lse);
+
+/**
+ * skb_mpls_dec_ttl() - decrement the TTL of the outermost MPLS header
+ *
+ * @skb: buffer
+ *
+ * Expects skb->data at mac header.
+ *
+ * Returns 0 on success, -errno otherwise.
+ */
+int skb_mpls_dec_ttl(struct sk_buff *skb)
+{
+	u32 lse;
+	u8 ttl;
+
+	if (unlikely(!eth_p_mpls(skb->protocol)))
+		return -EINVAL;
+
+	if (!pskb_may_pull(skb, skb_network_offset(skb) + MPLS_HLEN))
+		return -ENOMEM;
+
+	lse = be32_to_cpu(mpls_hdr(skb)->label_stack_entry);
+	ttl = (lse & MPLS_LS_TTL_MASK) >> MPLS_LS_TTL_SHIFT;
+	if (!--ttl)
+		return -EINVAL;
+
+	lse &= ~MPLS_LS_TTL_MASK;
+	lse |= ttl << MPLS_LS_TTL_SHIFT;
+
+	return skb_mpls_update_lse(skb, cpu_to_be32(lse));
+}
+EXPORT_SYMBOL_GPL(skb_mpls_dec_ttl);
+
+/**
+ * alloc_skb_with_frags - allocate skb with page frags
+ *
+ * @header_len: size of linear part
+ * @data_len: needed length in frags
+ * @max_page_order: max page order desired.
+ * @errcode: pointer to error code if any
+ * @gfp_mask: allocation mask
+ *
+ * This can be used to allocate a paged skb, given a maximal order for frags.
+ */
+struct sk_buff *alloc_skb_with_frags(unsigned long header_len,
+				     unsigned long data_len,
+				     int max_page_order,
+				     int *errcode,
+				     gfp_t gfp_mask)
+{
+	int npages = (data_len + (PAGE_SIZE - 1)) >> PAGE_SHIFT;
+	unsigned long chunk;
+	struct sk_buff *skb;
+	struct page *page;
+	int i;
+
+	*errcode = -EMSGSIZE;
+	/* Note this test could be relaxed, if we succeed to allocate
+	 * high order pages...
+	 */
+	if (npages > MAX_SKB_FRAGS)
+		return NULL;
+
+	*errcode = -ENOBUFS;
+	skb = alloc_skb(header_len, gfp_mask);
+	if (!skb)
+		return NULL;
+
+	skb->truesize += npages << PAGE_SHIFT;
+
+	for (i = 0; npages > 0; i++) {
+		int order = max_page_order;
+
+		while (order) {
+			if (npages >= 1 << order) {
+				page = alloc_pages((gfp_mask & ~__GFP_DIRECT_RECLAIM) |
+						   __GFP_COMP |
+						   __GFP_NOWARN,
+						   order);
+				if (page)
+					goto fill_page;
+				/* Do not retry other high order allocations */
+				order = 1;
+				max_page_order = 0;
+			}
+			order--;
+		}
+		page = alloc_page(gfp_mask);
+		if (!page)
+			goto failure;
+fill_page:
+		chunk = min_t(unsigned long, data_len,
+			      PAGE_SIZE << order);
+		skb_fill_page_desc(skb, i, page, 0, chunk);
+		data_len -= chunk;
+		npages -= 1 << order;
+	}
+	return skb;
+
+failure:
+	kfree_skb(skb);
+	return NULL;
+}
+EXPORT_SYMBOL(alloc_skb_with_frags);
+
+/* carve out the first off bytes from skb when off < headlen */
+static int pskb_carve_inside_header(struct sk_buff *skb, const u32 off,
+				    const int headlen, gfp_t gfp_mask)
+{
+	int i;
+	unsigned int size = skb_end_offset(skb);
+	int new_hlen = headlen - off;
+	u8 *data;
+
+	if (skb_pfmemalloc(skb))
+		gfp_mask |= __GFP_MEMALLOC;
+
+	data = kmalloc_reserve(&size, gfp_mask, NUMA_NO_NODE, NULL);
+	if (!data)
+		return -ENOMEM;
+	size = SKB_WITH_OVERHEAD(size);
+
+	/* Copy real data, and all frags */
+	skb_copy_from_linear_data_offset(skb, off, data, new_hlen);
+	skb->len -= off;
+
+	memcpy((struct skb_shared_info *)(data + size),
+	       skb_shinfo(skb),
+	       offsetof(struct skb_shared_info,
+			frags[skb_shinfo(skb)->nr_frags]));
+	if (skb_cloned(skb)) {
+		/* drop the old head gracefully */
+		if (skb_orphan_frags(skb, gfp_mask)) {
+			kfree(data);
+			return -ENOMEM;
+		}
+		for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
+			skb_frag_ref(skb, i);
+		if (skb_has_frag_list(skb))
+			skb_clone_fraglist(skb);
+		skb_release_data(skb);
+	} else {
+		/* we can reuse existing recount- all we did was
+		 * relocate values
+		 */
+		skb_free_head(skb);
+	}
+
+	skb->head = data;
+	skb->data = data;
+	skb->head_frag = 0;
+	skb_set_end_offset(skb, size);
+	skb_set_tail_pointer(skb, skb_headlen(skb));
+	skb_headers_offset_update(skb, 0);
+	skb->cloned = 0;
+	skb->hdr_len = 0;
+	skb->nohdr = 0;
+	atomic_set(&skb_shinfo(skb)->dataref, 1);
+
+	return 0;
+}
+
+static int pskb_carve(struct sk_buff *skb, const u32 off, gfp_t gfp);
+
+/* carve out the first eat bytes from skb's frag_list. May recurse into
+ * pskb_carve()
+ */
+static int pskb_carve_frag_list(struct sk_buff *skb,
+				struct skb_shared_info *shinfo, int eat,
+				gfp_t gfp_mask)
+{
+	struct sk_buff *list = shinfo->frag_list;
+	struct sk_buff *clone = NULL;
+	struct sk_buff *insp = NULL;
+
+	do {
+		if (!list) {
+			pr_err("Not enough bytes to eat. Want %d\n", eat);
+			return -EFAULT;
+		}
+		if (list->len <= eat) {
+			/* Eaten as whole. */
+			eat -= list->len;
+			list = list->next;
+			insp = list;
+		} else {
+			/* Eaten partially. */
+			if (skb_shared(list)) {
+				clone = skb_clone(list, gfp_mask);
+				if (!clone)
+					return -ENOMEM;
+				insp = list->next;
+				list = clone;
+			} else {
+				/* This may be pulled without problems. */
+				insp = list;
+			}
+			if (pskb_carve(list, eat, gfp_mask) < 0) {
+				kfree_skb(clone);
+				return -ENOMEM;
+			}
+			break;
+		}
+	} while (eat);
+
+	/* Free pulled out fragments. */
+	while ((list = shinfo->frag_list) != insp) {
+		shinfo->frag_list = list->next;
+		consume_skb(list);
+	}
+	/* And insert new clone at head. */
+	if (clone) {
+		clone->next = list;
+		shinfo->frag_list = clone;
+	}
+	return 0;
+}
+
+/* carve off first len bytes from skb. Split line (off) is in the
+ * non-linear part of skb
+ */
+static int pskb_carve_inside_nonlinear(struct sk_buff *skb, const u32 off,
+				       int pos, gfp_t gfp_mask)
+{
+	int i, k = 0;
+	unsigned int size = skb_end_offset(skb);
+	u8 *data;
+	const int nfrags = skb_shinfo(skb)->nr_frags;
+	struct skb_shared_info *shinfo;
+
+	if (skb_pfmemalloc(skb))
+		gfp_mask |= __GFP_MEMALLOC;
+
+	data = kmalloc_reserve(&size, gfp_mask, NUMA_NO_NODE, NULL);
+	if (!data)
+		return -ENOMEM;
+	size = SKB_WITH_OVERHEAD(size);
+
+	memcpy((struct skb_shared_info *)(data + size),
+	       skb_shinfo(skb), offsetof(struct skb_shared_info, frags[0]));
+	if (skb_orphan_frags(skb, gfp_mask)) {
+		kfree(data);
+		return -ENOMEM;
+	}
+	shinfo = (struct skb_shared_info *)(data + size);
+	for (i = 0; i < nfrags; i++) {
+		int fsize = skb_frag_size(&skb_shinfo(skb)->frags[i]);
+
+		if (pos + fsize > off) {
+			shinfo->frags[k] = skb_shinfo(skb)->frags[i];
+
+			if (pos < off) {
+				/* Split frag.
+				 * We have two variants in this case:
+				 * 1. Move all the frag to the second
+				 *    part, if it is possible. F.e.
+				 *    this approach is mandatory for TUX,
+				 *    where splitting is expensive.
+				 * 2. Split is accurately. We make this.
+				 */
+				skb_frag_off_add(&shinfo->frags[0], off - pos);
+				skb_frag_size_sub(&shinfo->frags[0], off - pos);
+			}
+			skb_frag_ref(skb, i);
+			k++;
+		}
+		pos += fsize;
+	}
+	shinfo->nr_frags = k;
+	if (skb_has_frag_list(skb))
+		skb_clone_fraglist(skb);
+
+	/* split line is in frag list */
+	if (k == 0 && pskb_carve_frag_list(skb, shinfo, off - pos, gfp_mask)) {
+		/* skb_frag_unref() is not needed here as shinfo->nr_frags = 0. */
+		if (skb_has_frag_list(skb))
+			kfree_skb_list(skb_shinfo(skb)->frag_list);
+		kfree(data);
+		return -ENOMEM;
+	}
+	skb_release_data(skb);
+
+	skb->head = data;
+	skb->head_frag = 0;
+	skb->data = data;
+	skb_set_end_offset(skb, size);
+	skb_reset_tail_pointer(skb);
+	skb_headers_offset_update(skb, 0);
+	skb->cloned   = 0;
+	skb->hdr_len  = 0;
+	skb->nohdr    = 0;
+	skb->len -= off;
+	skb->data_len = skb->len;
+	atomic_set(&skb_shinfo(skb)->dataref, 1);
+	return 0;
+}
+
+/* remove len bytes from the beginning of the skb */
+static int pskb_carve(struct sk_buff *skb, const u32 len, gfp_t gfp)
+{
+	int headlen = skb_headlen(skb);
+
+	if (len < headlen)
+		return pskb_carve_inside_header(skb, len, headlen, gfp);
+	else
+		return pskb_carve_inside_nonlinear(skb, len, headlen, gfp);
+}
+
+/* Extract to_copy bytes starting at off from skb, and return this in
+ * a new skb
+ */
+struct sk_buff *pskb_extract(struct sk_buff *skb, int off,
+			     int to_copy, gfp_t gfp)
+{
+	struct sk_buff  *clone = skb_clone(skb, gfp);
+
+	if (!clone)
+		return NULL;
+
+	if (pskb_carve(clone, off, gfp) < 0 ||
+	    pskb_trim(clone, to_copy)) {
+		kfree_skb(clone);
+		return NULL;
+	}
+	return clone;
+}
+EXPORT_SYMBOL(pskb_extract);
+
+/**
+ * skb_condense - try to get rid of fragments/frag_list if possible
+ * @skb: buffer
+ *
+ * Can be used to save memory before skb is added to a busy queue.
+ * If packet has bytes in frags and enough tail room in skb->head,
+ * pull all of them, so that we can free the frags right now and adjust
+ * truesize.
+ * Notes:
+ *	We do not reallocate skb->head thus can not fail.
+ *	Caller must re-evaluate skb->truesize if needed.
+ */
+void skb_condense(struct sk_buff *skb)
+{
+	if (skb->data_len) {
+		if (skb->data_len > skb->end - skb->tail ||
+		    skb_cloned(skb))
+			return;
+
+		/* Nice, we can free page frag(s) right now */
+		__pskb_pull_tail(skb, skb->data_len);
+	}
+	/* At this point, skb->truesize might be over estimated,
+	 * because skb had a fragment, and fragments do not tell
+	 * their truesize.
+	 * When we pulled its content into skb->head, fragment
+	 * was freed, but __pskb_pull_tail() could not possibly
+	 * adjust skb->truesize, not knowing the frag truesize.
+	 */
+	skb->truesize = SKB_TRUESIZE(skb_end_offset(skb));
+}
+
+#ifdef CONFIG_SKB_EXTENSIONS
+static void *skb_ext_get_ptr(struct skb_ext *ext, enum skb_ext_id id)
+{
+	return (void *)ext + (ext->offset[id] * SKB_EXT_ALIGN_VALUE);
+}
+
+/**
+ * __skb_ext_alloc - allocate a new skb extensions storage
+ *
+ * @flags: See kmalloc().
+ *
+ * Returns the newly allocated pointer. The pointer can later attached to a
+ * skb via __skb_ext_set().
+ * Note: caller must handle the skb_ext as an opaque data.
+ */
+struct skb_ext *__skb_ext_alloc(gfp_t flags)
+{
+	struct skb_ext *new = kmem_cache_alloc(skbuff_ext_cache, flags);
+
+	if (new) {
+		memset(new->offset, 0, sizeof(new->offset));
+		refcount_set(&new->refcnt, 1);
+	}
+
+	return new;
+}
+
+static struct skb_ext *skb_ext_maybe_cow(struct skb_ext *old,
+					 unsigned int old_active)
+{
+	struct skb_ext *new;
+
+	if (refcount_read(&old->refcnt) == 1)
+		return old;
+
+	new = kmem_cache_alloc(skbuff_ext_cache, GFP_ATOMIC);
+	if (!new)
+		return NULL;
+
+	memcpy(new, old, old->chunks * SKB_EXT_ALIGN_VALUE);
+	refcount_set(&new->refcnt, 1);
+
+#ifdef CONFIG_XFRM
+	if (old_active & (1 << SKB_EXT_SEC_PATH)) {
+		struct sec_path *sp = skb_ext_get_ptr(old, SKB_EXT_SEC_PATH);
+		unsigned int i;
+
+		for (i = 0; i < sp->len; i++)
+			xfrm_state_hold(sp->xvec[i]);
+	}
+#endif
+	__skb_ext_put(old);
+	return new;
+}
+
+/**
+ * __skb_ext_set - attach the specified extension storage to this skb
+ * @skb: buffer
+ * @id: extension id
+ * @ext: extension storage previously allocated via __skb_ext_alloc()
+ *
+ * Existing extensions, if any, are cleared.
+ *
+ * Returns the pointer to the extension.
+ */
+void *__skb_ext_set(struct sk_buff *skb, enum skb_ext_id id,
+		    struct skb_ext *ext)
+{
+	unsigned int newlen, newoff = SKB_EXT_CHUNKSIZEOF(*ext);
+
+	skb_ext_put(skb);
+	newlen = newoff + skb_ext_type_len[id];
+	ext->chunks = newlen;
+	ext->offset[id] = newoff;
+	skb->extensions = ext;
+	skb->active_extensions = 1 << id;
+	return skb_ext_get_ptr(ext, id);
+}
+
+/**
+ * skb_ext_add - allocate space for given extension, COW if needed
+ * @skb: buffer
+ * @id: extension to allocate space for
+ *
+ * Allocates enough space for the given extension.
+ * If the extension is already present, a pointer to that extension
+ * is returned.
+ *
+ * If the skb was cloned, COW applies and the returned memory can be
+ * modified without changing the extension space of clones buffers.
+ *
+ * Returns pointer to the extension or NULL on allocation failure.
+ */
+void *skb_ext_add(struct sk_buff *skb, enum skb_ext_id id)
+{
+	struct skb_ext *new, *old = NULL;
+	unsigned int newlen, newoff;
+
+	if (skb->active_extensions) {
+		old = skb->extensions;
+
+		new = skb_ext_maybe_cow(old, skb->active_extensions);
+		if (!new)
+			return NULL;
+
+		if (__skb_ext_exist(new, id))
+			goto set_active;
+
+		newoff = new->chunks;
+	} else {
+		newoff = SKB_EXT_CHUNKSIZEOF(*new);
+
+		new = __skb_ext_alloc(GFP_ATOMIC);
+		if (!new)
+			return NULL;
+	}
+
+	newlen = newoff + skb_ext_type_len[id];
+	new->chunks = newlen;
+	new->offset[id] = newoff;
+set_active:
+	skb->slow_gro = 1;
+	skb->extensions = new;
+	skb->active_extensions |= 1 << id;
+	return skb_ext_get_ptr(new, id);
+}
+EXPORT_SYMBOL(skb_ext_add);
+
+#ifdef CONFIG_XFRM
+static void skb_ext_put_sp(struct sec_path *sp)
+{
+	unsigned int i;
+
+	for (i = 0; i < sp->len; i++)
+		xfrm_state_put(sp->xvec[i]);
+}
+#endif
+
+#ifdef CONFIG_MCTP_FLOWS
+static void skb_ext_put_mctp(struct mctp_flow *flow)
+{
+	if (flow->key)
+		mctp_key_unref(flow->key);
+}
+#endif
+
+void __skb_ext_del(struct sk_buff *skb, enum skb_ext_id id)
+{
+	struct skb_ext *ext = skb->extensions;
+
+	skb->active_extensions &= ~(1 << id);
+	if (skb->active_extensions == 0) {
+		skb->extensions = NULL;
+		__skb_ext_put(ext);
+#ifdef CONFIG_XFRM
+	} else if (id == SKB_EXT_SEC_PATH &&
+		   refcount_read(&ext->refcnt) == 1) {
+		struct sec_path *sp = skb_ext_get_ptr(ext, SKB_EXT_SEC_PATH);
+
+		skb_ext_put_sp(sp);
+		sp->len = 0;
+#endif
+	}
+}
+EXPORT_SYMBOL(__skb_ext_del);
+
+void __skb_ext_put(struct skb_ext *ext)
+{
+	/* If this is last clone, nothing can increment
+	 * it after check passes.  Avoids one atomic op.
+	 */
+	if (refcount_read(&ext->refcnt) == 1)
+		goto free_now;
+
+	if (!refcount_dec_and_test(&ext->refcnt))
+		return;
+free_now:
+#ifdef CONFIG_XFRM
+	if (__skb_ext_exist(ext, SKB_EXT_SEC_PATH))
+		skb_ext_put_sp(skb_ext_get_ptr(ext, SKB_EXT_SEC_PATH));
+#endif
+#ifdef CONFIG_MCTP_FLOWS
+	if (__skb_ext_exist(ext, SKB_EXT_MCTP))
+		skb_ext_put_mctp(skb_ext_get_ptr(ext, SKB_EXT_MCTP));
+#endif
+
+	kmem_cache_free(skbuff_ext_cache, ext);
+}
+EXPORT_SYMBOL(__skb_ext_put);
+#endif /* CONFIG_SKB_EXTENSIONS */
+
+/**
+ * skb_attempt_defer_free - queue skb for remote freeing
+ * @skb: buffer
+ *
+ * Put @skb in a per-cpu list, using the cpu which
+ * allocated the skb/pages to reduce false sharing
+ * and memory zone spinlock contention.
+ */
+void skb_attempt_defer_free(struct sk_buff *skb)
+{
+	int cpu = skb->alloc_cpu;
+	struct softnet_data *sd;
+	unsigned long flags;
+	unsigned int defer_max;
+	bool kick;
+
+	if (WARN_ON_ONCE(cpu >= nr_cpu_ids) ||
+	    !cpu_online(cpu) ||
+	    cpu == raw_smp_processor_id()) {
+nodefer:	__kfree_skb(skb);
+		return;
+	}
+
+	sd = &per_cpu(softnet_data, cpu);
+	defer_max = READ_ONCE(sysctl_skb_defer_max);
+	if (READ_ONCE(sd->defer_count) >= defer_max)
+		goto nodefer;
+
+	spin_lock_irqsave(&sd->defer_lock, flags);
+	/* Send an IPI every time queue reaches half capacity. */
+	kick = sd->defer_count == (defer_max >> 1);
+	/* Paired with the READ_ONCE() few lines above */
+	WRITE_ONCE(sd->defer_count, sd->defer_count + 1);
+
+	skb->next = sd->defer_list;
+	/* Paired with READ_ONCE() in skb_defer_free_flush() */
+	WRITE_ONCE(sd->defer_list, skb);
+	spin_unlock_irqrestore(&sd->defer_lock, flags);
+
+	/* Make sure to trigger NET_RX_SOFTIRQ on the remote CPU
+	 * if we are unlucky enough (this seems very unlikely).
+	 */
+	if (unlikely(kick) && !cmpxchg(&sd->defer_ipi_scheduled, 0, 1))
+		smp_call_function_single_async(cpu, &sd->defer_csd);
+}