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-rw-r--r--include/net/page_pool.h386
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diff --git a/include/net/page_pool.h b/include/net/page_pool.h
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+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * page_pool.h
+ * Author: Jesper Dangaard Brouer <netoptimizer@brouer.com>
+ * Copyright (C) 2016 Red Hat, Inc.
+ */
+
+/**
+ * DOC: page_pool allocator
+ *
+ * This page_pool allocator is optimized for the XDP mode that
+ * uses one-frame-per-page, but have fallbacks that act like the
+ * regular page allocator APIs.
+ *
+ * Basic use involve replacing alloc_pages() calls with the
+ * page_pool_alloc_pages() call. Drivers should likely use
+ * page_pool_dev_alloc_pages() replacing dev_alloc_pages().
+ *
+ * API keeps track of in-flight pages, in-order to let API user know
+ * when it is safe to dealloactor page_pool object. Thus, API users
+ * must make sure to call page_pool_release_page() when a page is
+ * "leaving" the page_pool. Or call page_pool_put_page() where
+ * appropiate. For maintaining correct accounting.
+ *
+ * API user must only call page_pool_put_page() once on a page, as it
+ * will either recycle the page, or in case of elevated refcnt, it
+ * will release the DMA mapping and in-flight state accounting. We
+ * hope to lift this requirement in the future.
+ */
+#ifndef _NET_PAGE_POOL_H
+#define _NET_PAGE_POOL_H
+
+#include <linux/mm.h> /* Needed by ptr_ring */
+#include <linux/ptr_ring.h>
+#include <linux/dma-direction.h>
+
+#define PP_FLAG_DMA_MAP BIT(0) /* Should page_pool do the DMA
+ * map/unmap
+ */
+#define PP_FLAG_DMA_SYNC_DEV BIT(1) /* If set all pages that the driver gets
+ * from page_pool will be
+ * DMA-synced-for-device according to
+ * the length provided by the device
+ * driver.
+ * Please note DMA-sync-for-CPU is still
+ * device driver responsibility
+ */
+#define PP_FLAG_PAGE_FRAG BIT(2) /* for page frag feature */
+#define PP_FLAG_ALL (PP_FLAG_DMA_MAP |\
+ PP_FLAG_DMA_SYNC_DEV |\
+ PP_FLAG_PAGE_FRAG)
+
+/*
+ * Fast allocation side cache array/stack
+ *
+ * The cache size and refill watermark is related to the network
+ * use-case. The NAPI budget is 64 packets. After a NAPI poll the RX
+ * ring is usually refilled and the max consumed elements will be 64,
+ * thus a natural max size of objects needed in the cache.
+ *
+ * Keeping room for more objects, is due to XDP_DROP use-case. As
+ * XDP_DROP allows the opportunity to recycle objects directly into
+ * this array, as it shares the same softirq/NAPI protection. If
+ * cache is already full (or partly full) then the XDP_DROP recycles
+ * would have to take a slower code path.
+ */
+#define PP_ALLOC_CACHE_SIZE 128
+#define PP_ALLOC_CACHE_REFILL 64
+struct pp_alloc_cache {
+ u32 count;
+ struct page *cache[PP_ALLOC_CACHE_SIZE];
+};
+
+struct page_pool_params {
+ unsigned int flags;
+ unsigned int order;
+ unsigned int pool_size;
+ int nid; /* Numa node id to allocate from pages from */
+ struct device *dev; /* device, for DMA pre-mapping purposes */
+ enum dma_data_direction dma_dir; /* DMA mapping direction */
+ unsigned int max_len; /* max DMA sync memory size */
+ unsigned int offset; /* DMA addr offset */
+ void (*init_callback)(struct page *page, void *arg);
+ void *init_arg;
+};
+
+#ifdef CONFIG_PAGE_POOL_STATS
+struct page_pool_alloc_stats {
+ u64 fast; /* fast path allocations */
+ u64 slow; /* slow-path order 0 allocations */
+ u64 slow_high_order; /* slow-path high order allocations */
+ u64 empty; /* failed refills due to empty ptr ring, forcing
+ * slow path allocation
+ */
+ u64 refill; /* allocations via successful refill */
+ u64 waive; /* failed refills due to numa zone mismatch */
+};
+
+struct page_pool_recycle_stats {
+ u64 cached; /* recycling placed page in the cache. */
+ u64 cache_full; /* cache was full */
+ u64 ring; /* recycling placed page back into ptr ring */
+ u64 ring_full; /* page was released from page-pool because
+ * PTR ring was full.
+ */
+ u64 released_refcnt; /* page released because of elevated
+ * refcnt
+ */
+};
+
+/* This struct wraps the above stats structs so users of the
+ * page_pool_get_stats API can pass a single argument when requesting the
+ * stats for the page pool.
+ */
+struct page_pool_stats {
+ struct page_pool_alloc_stats alloc_stats;
+ struct page_pool_recycle_stats recycle_stats;
+};
+
+int page_pool_ethtool_stats_get_count(void);
+u8 *page_pool_ethtool_stats_get_strings(u8 *data);
+u64 *page_pool_ethtool_stats_get(u64 *data, void *stats);
+
+/*
+ * Drivers that wish to harvest page pool stats and report them to users
+ * (perhaps via ethtool, debugfs, or another mechanism) can allocate a
+ * struct page_pool_stats call page_pool_get_stats to get stats for the specified pool.
+ */
+bool page_pool_get_stats(struct page_pool *pool,
+ struct page_pool_stats *stats);
+#else
+
+static inline int page_pool_ethtool_stats_get_count(void)
+{
+ return 0;
+}
+
+static inline u8 *page_pool_ethtool_stats_get_strings(u8 *data)
+{
+ return data;
+}
+
+static inline u64 *page_pool_ethtool_stats_get(u64 *data, void *stats)
+{
+ return data;
+}
+
+#endif
+
+struct page_pool {
+ struct page_pool_params p;
+
+ struct delayed_work release_dw;
+ void (*disconnect)(void *);
+ unsigned long defer_start;
+ unsigned long defer_warn;
+
+ u32 pages_state_hold_cnt;
+ unsigned int frag_offset;
+ struct page *frag_page;
+ long frag_users;
+
+#ifdef CONFIG_PAGE_POOL_STATS
+ /* these stats are incremented while in softirq context */
+ struct page_pool_alloc_stats alloc_stats;
+#endif
+ u32 xdp_mem_id;
+
+ /*
+ * Data structure for allocation side
+ *
+ * Drivers allocation side usually already perform some kind
+ * of resource protection. Piggyback on this protection, and
+ * require driver to protect allocation side.
+ *
+ * For NIC drivers this means, allocate a page_pool per
+ * RX-queue. As the RX-queue is already protected by
+ * Softirq/BH scheduling and napi_schedule. NAPI schedule
+ * guarantee that a single napi_struct will only be scheduled
+ * on a single CPU (see napi_schedule).
+ */
+ struct pp_alloc_cache alloc ____cacheline_aligned_in_smp;
+
+ /* Data structure for storing recycled pages.
+ *
+ * Returning/freeing pages is more complicated synchronization
+ * wise, because free's can happen on remote CPUs, with no
+ * association with allocation resource.
+ *
+ * Use ptr_ring, as it separates consumer and producer
+ * effeciently, it a way that doesn't bounce cache-lines.
+ *
+ * TODO: Implement bulk return pages into this structure.
+ */
+ struct ptr_ring ring;
+
+#ifdef CONFIG_PAGE_POOL_STATS
+ /* recycle stats are per-cpu to avoid locking */
+ struct page_pool_recycle_stats __percpu *recycle_stats;
+#endif
+ atomic_t pages_state_release_cnt;
+
+ /* A page_pool is strictly tied to a single RX-queue being
+ * protected by NAPI, due to above pp_alloc_cache. This
+ * refcnt serves purpose is to simplify drivers error handling.
+ */
+ refcount_t user_cnt;
+
+ u64 destroy_cnt;
+};
+
+struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp);
+
+static inline struct page *page_pool_dev_alloc_pages(struct page_pool *pool)
+{
+ gfp_t gfp = (GFP_ATOMIC | __GFP_NOWARN);
+
+ return page_pool_alloc_pages(pool, gfp);
+}
+
+struct page *page_pool_alloc_frag(struct page_pool *pool, unsigned int *offset,
+ unsigned int size, gfp_t gfp);
+
+static inline struct page *page_pool_dev_alloc_frag(struct page_pool *pool,
+ unsigned int *offset,
+ unsigned int size)
+{
+ gfp_t gfp = (GFP_ATOMIC | __GFP_NOWARN);
+
+ return page_pool_alloc_frag(pool, offset, size, gfp);
+}
+
+/* get the stored dma direction. A driver might decide to treat this locally and
+ * avoid the extra cache line from page_pool to determine the direction
+ */
+static
+inline enum dma_data_direction page_pool_get_dma_dir(struct page_pool *pool)
+{
+ return pool->p.dma_dir;
+}
+
+bool page_pool_return_skb_page(struct page *page);
+
+struct page_pool *page_pool_create(const struct page_pool_params *params);
+
+struct xdp_mem_info;
+
+#ifdef CONFIG_PAGE_POOL
+void page_pool_destroy(struct page_pool *pool);
+void page_pool_use_xdp_mem(struct page_pool *pool, void (*disconnect)(void *),
+ struct xdp_mem_info *mem);
+void page_pool_release_page(struct page_pool *pool, struct page *page);
+void page_pool_put_page_bulk(struct page_pool *pool, void **data,
+ int count);
+#else
+static inline void page_pool_destroy(struct page_pool *pool)
+{
+}
+
+static inline void page_pool_use_xdp_mem(struct page_pool *pool,
+ void (*disconnect)(void *),
+ struct xdp_mem_info *mem)
+{
+}
+static inline void page_pool_release_page(struct page_pool *pool,
+ struct page *page)
+{
+}
+
+static inline void page_pool_put_page_bulk(struct page_pool *pool, void **data,
+ int count)
+{
+}
+#endif
+
+void page_pool_put_defragged_page(struct page_pool *pool, struct page *page,
+ unsigned int dma_sync_size,
+ bool allow_direct);
+
+static inline void page_pool_fragment_page(struct page *page, long nr)
+{
+ atomic_long_set(&page->pp_frag_count, nr);
+}
+
+static inline long page_pool_defrag_page(struct page *page, long nr)
+{
+ long ret;
+
+ /* If nr == pp_frag_count then we have cleared all remaining
+ * references to the page. No need to actually overwrite it, instead
+ * we can leave this to be overwritten by the calling function.
+ *
+ * The main advantage to doing this is that an atomic_read is
+ * generally a much cheaper operation than an atomic update,
+ * especially when dealing with a page that may be partitioned
+ * into only 2 or 3 pieces.
+ */
+ if (atomic_long_read(&page->pp_frag_count) == nr)
+ return 0;
+
+ ret = atomic_long_sub_return(nr, &page->pp_frag_count);
+ WARN_ON(ret < 0);
+ return ret;
+}
+
+static inline bool page_pool_is_last_frag(struct page_pool *pool,
+ struct page *page)
+{
+ /* If fragments aren't enabled or count is 0 we were the last user */
+ return !(pool->p.flags & PP_FLAG_PAGE_FRAG) ||
+ (page_pool_defrag_page(page, 1) == 0);
+}
+
+static inline void page_pool_put_page(struct page_pool *pool,
+ struct page *page,
+ unsigned int dma_sync_size,
+ bool allow_direct)
+{
+ /* When page_pool isn't compiled-in, net/core/xdp.c doesn't
+ * allow registering MEM_TYPE_PAGE_POOL, but shield linker.
+ */
+#ifdef CONFIG_PAGE_POOL
+ if (!page_pool_is_last_frag(pool, page))
+ return;
+
+ page_pool_put_defragged_page(pool, page, dma_sync_size, allow_direct);
+#endif
+}
+
+/* Same as above but will try to sync the entire area pool->max_len */
+static inline void page_pool_put_full_page(struct page_pool *pool,
+ struct page *page, bool allow_direct)
+{
+ page_pool_put_page(pool, page, -1, allow_direct);
+}
+
+/* Same as above but the caller must guarantee safe context. e.g NAPI */
+static inline void page_pool_recycle_direct(struct page_pool *pool,
+ struct page *page)
+{
+ page_pool_put_full_page(pool, page, true);
+}
+
+#define PAGE_POOL_DMA_USE_PP_FRAG_COUNT \
+ (sizeof(dma_addr_t) > sizeof(unsigned long))
+
+static inline dma_addr_t page_pool_get_dma_addr(struct page *page)
+{
+ dma_addr_t ret = page->dma_addr;
+
+ if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT)
+ ret |= (dma_addr_t)page->dma_addr_upper << 16 << 16;
+
+ return ret;
+}
+
+static inline void page_pool_set_dma_addr(struct page *page, dma_addr_t addr)
+{
+ page->dma_addr = addr;
+ if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT)
+ page->dma_addr_upper = upper_32_bits(addr);
+}
+
+static inline bool is_page_pool_compiled_in(void)
+{
+#ifdef CONFIG_PAGE_POOL
+ return true;
+#else
+ return false;
+#endif
+}
+
+static inline bool page_pool_put(struct page_pool *pool)
+{
+ return refcount_dec_and_test(&pool->user_cnt);
+}
+
+/* Caller must provide appropriate safe context, e.g. NAPI. */
+void page_pool_update_nid(struct page_pool *pool, int new_nid);
+static inline void page_pool_nid_changed(struct page_pool *pool, int new_nid)
+{
+ if (unlikely(pool->p.nid != new_nid))
+ page_pool_update_nid(pool, new_nid);
+}
+
+#endif /* _NET_PAGE_POOL_H */