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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
commit | 2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch) | |
tree | 848558de17fb3008cdf4d861b01ac7781903ce39 /net/core/datagram.c | |
parent | Initial commit. (diff) | |
download | linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip |
Adding upstream version 6.1.76.upstream/6.1.76
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'net/core/datagram.c')
-rw-r--r-- | net/core/datagram.c | 842 |
1 files changed, 842 insertions, 0 deletions
diff --git a/net/core/datagram.c b/net/core/datagram.c new file mode 100644 index 000000000..8dabb9a74 --- /dev/null +++ b/net/core/datagram.c @@ -0,0 +1,842 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * SUCS NET3: + * + * Generic datagram handling routines. These are generic for all + * protocols. Possibly a generic IP version on top of these would + * make sense. Not tonight however 8-). + * This is used because UDP, RAW, PACKET, DDP, IPX, AX.25 and + * NetROM layer all have identical poll code and mostly + * identical recvmsg() code. So we share it here. The poll was + * shared before but buried in udp.c so I moved it. + * + * Authors: Alan Cox <alan@lxorguk.ukuu.org.uk>. (datagram_poll() from old + * udp.c code) + * + * Fixes: + * Alan Cox : NULL return from skb_peek_copy() + * understood + * Alan Cox : Rewrote skb_read_datagram to avoid the + * skb_peek_copy stuff. + * Alan Cox : Added support for SOCK_SEQPACKET. + * IPX can no longer use the SO_TYPE hack + * but AX.25 now works right, and SPX is + * feasible. + * Alan Cox : Fixed write poll of non IP protocol + * crash. + * Florian La Roche: Changed for my new skbuff handling. + * Darryl Miles : Fixed non-blocking SOCK_SEQPACKET. + * Linus Torvalds : BSD semantic fixes. + * Alan Cox : Datagram iovec handling + * Darryl Miles : Fixed non-blocking SOCK_STREAM. + * Alan Cox : POSIXisms + * Pete Wyckoff : Unconnected accept() fix. + * + */ + +#include <linux/module.h> +#include <linux/types.h> +#include <linux/kernel.h> +#include <linux/uaccess.h> +#include <linux/mm.h> +#include <linux/interrupt.h> +#include <linux/errno.h> +#include <linux/sched.h> +#include <linux/inet.h> +#include <linux/netdevice.h> +#include <linux/rtnetlink.h> +#include <linux/poll.h> +#include <linux/highmem.h> +#include <linux/spinlock.h> +#include <linux/slab.h> +#include <linux/pagemap.h> +#include <linux/uio.h> +#include <linux/indirect_call_wrapper.h> + +#include <net/protocol.h> +#include <linux/skbuff.h> + +#include <net/checksum.h> +#include <net/sock.h> +#include <net/tcp_states.h> +#include <trace/events/skb.h> +#include <net/busy_poll.h> + +/* + * Is a socket 'connection oriented' ? + */ +static inline int connection_based(struct sock *sk) +{ + return sk->sk_type == SOCK_SEQPACKET || sk->sk_type == SOCK_STREAM; +} + +static int receiver_wake_function(wait_queue_entry_t *wait, unsigned int mode, int sync, + void *key) +{ + /* + * Avoid a wakeup if event not interesting for us + */ + if (key && !(key_to_poll(key) & (EPOLLIN | EPOLLERR))) + return 0; + return autoremove_wake_function(wait, mode, sync, key); +} +/* + * Wait for the last received packet to be different from skb + */ +int __skb_wait_for_more_packets(struct sock *sk, struct sk_buff_head *queue, + int *err, long *timeo_p, + const struct sk_buff *skb) +{ + int error; + DEFINE_WAIT_FUNC(wait, receiver_wake_function); + + prepare_to_wait_exclusive(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE); + + /* Socket errors? */ + error = sock_error(sk); + if (error) + goto out_err; + + if (READ_ONCE(queue->prev) != skb) + goto out; + + /* Socket shut down? */ + if (sk->sk_shutdown & RCV_SHUTDOWN) + goto out_noerr; + + /* Sequenced packets can come disconnected. + * If so we report the problem + */ + error = -ENOTCONN; + if (connection_based(sk) && + !(sk->sk_state == TCP_ESTABLISHED || sk->sk_state == TCP_LISTEN)) + goto out_err; + + /* handle signals */ + if (signal_pending(current)) + goto interrupted; + + error = 0; + *timeo_p = schedule_timeout(*timeo_p); +out: + finish_wait(sk_sleep(sk), &wait); + return error; +interrupted: + error = sock_intr_errno(*timeo_p); +out_err: + *err = error; + goto out; +out_noerr: + *err = 0; + error = 1; + goto out; +} +EXPORT_SYMBOL(__skb_wait_for_more_packets); + +static struct sk_buff *skb_set_peeked(struct sk_buff *skb) +{ + struct sk_buff *nskb; + + if (skb->peeked) + return skb; + + /* We have to unshare an skb before modifying it. */ + if (!skb_shared(skb)) + goto done; + + nskb = skb_clone(skb, GFP_ATOMIC); + if (!nskb) + return ERR_PTR(-ENOMEM); + + skb->prev->next = nskb; + skb->next->prev = nskb; + nskb->prev = skb->prev; + nskb->next = skb->next; + + consume_skb(skb); + skb = nskb; + +done: + skb->peeked = 1; + + return skb; +} + +struct sk_buff *__skb_try_recv_from_queue(struct sock *sk, + struct sk_buff_head *queue, + unsigned int flags, + int *off, int *err, + struct sk_buff **last) +{ + bool peek_at_off = false; + struct sk_buff *skb; + int _off = 0; + + if (unlikely(flags & MSG_PEEK && *off >= 0)) { + peek_at_off = true; + _off = *off; + } + + *last = queue->prev; + skb_queue_walk(queue, skb) { + if (flags & MSG_PEEK) { + if (peek_at_off && _off >= skb->len && + (_off || skb->peeked)) { + _off -= skb->len; + continue; + } + if (!skb->len) { + skb = skb_set_peeked(skb); + if (IS_ERR(skb)) { + *err = PTR_ERR(skb); + return NULL; + } + } + refcount_inc(&skb->users); + } else { + __skb_unlink(skb, queue); + } + *off = _off; + return skb; + } + return NULL; +} + +/** + * __skb_try_recv_datagram - Receive a datagram skbuff + * @sk: socket + * @queue: socket queue from which to receive + * @flags: MSG\_ flags + * @off: an offset in bytes to peek skb from. Returns an offset + * within an skb where data actually starts + * @err: error code returned + * @last: set to last peeked message to inform the wait function + * what to look for when peeking + * + * Get a datagram skbuff, understands the peeking, nonblocking wakeups + * and possible races. This replaces identical code in packet, raw and + * udp, as well as the IPX AX.25 and Appletalk. It also finally fixes + * the long standing peek and read race for datagram sockets. If you + * alter this routine remember it must be re-entrant. + * + * This function will lock the socket if a skb is returned, so + * the caller needs to unlock the socket in that case (usually by + * calling skb_free_datagram). Returns NULL with @err set to + * -EAGAIN if no data was available or to some other value if an + * error was detected. + * + * * It does not lock socket since today. This function is + * * free of race conditions. This measure should/can improve + * * significantly datagram socket latencies at high loads, + * * when data copying to user space takes lots of time. + * * (BTW I've just killed the last cli() in IP/IPv6/core/netlink/packet + * * 8) Great win.) + * * --ANK (980729) + * + * The order of the tests when we find no data waiting are specified + * quite explicitly by POSIX 1003.1g, don't change them without having + * the standard around please. + */ +struct sk_buff *__skb_try_recv_datagram(struct sock *sk, + struct sk_buff_head *queue, + unsigned int flags, int *off, int *err, + struct sk_buff **last) +{ + struct sk_buff *skb; + unsigned long cpu_flags; + /* + * Caller is allowed not to check sk->sk_err before skb_recv_datagram() + */ + int error = sock_error(sk); + + if (error) + goto no_packet; + + do { + /* Again only user level code calls this function, so nothing + * interrupt level will suddenly eat the receive_queue. + * + * Look at current nfs client by the way... + * However, this function was correct in any case. 8) + */ + spin_lock_irqsave(&queue->lock, cpu_flags); + skb = __skb_try_recv_from_queue(sk, queue, flags, off, &error, + last); + spin_unlock_irqrestore(&queue->lock, cpu_flags); + if (error) + goto no_packet; + if (skb) + return skb; + + if (!sk_can_busy_loop(sk)) + break; + + sk_busy_loop(sk, flags & MSG_DONTWAIT); + } while (READ_ONCE(queue->prev) != *last); + + error = -EAGAIN; + +no_packet: + *err = error; + return NULL; +} +EXPORT_SYMBOL(__skb_try_recv_datagram); + +struct sk_buff *__skb_recv_datagram(struct sock *sk, + struct sk_buff_head *sk_queue, + unsigned int flags, int *off, int *err) +{ + struct sk_buff *skb, *last; + long timeo; + + timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT); + + do { + skb = __skb_try_recv_datagram(sk, sk_queue, flags, off, err, + &last); + if (skb) + return skb; + + if (*err != -EAGAIN) + break; + } while (timeo && + !__skb_wait_for_more_packets(sk, sk_queue, err, + &timeo, last)); + + return NULL; +} +EXPORT_SYMBOL(__skb_recv_datagram); + +struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned int flags, + int *err) +{ + int off = 0; + + return __skb_recv_datagram(sk, &sk->sk_receive_queue, flags, + &off, err); +} +EXPORT_SYMBOL(skb_recv_datagram); + +void skb_free_datagram(struct sock *sk, struct sk_buff *skb) +{ + consume_skb(skb); +} +EXPORT_SYMBOL(skb_free_datagram); + +void __skb_free_datagram_locked(struct sock *sk, struct sk_buff *skb, int len) +{ + bool slow; + + if (!skb_unref(skb)) { + sk_peek_offset_bwd(sk, len); + return; + } + + slow = lock_sock_fast(sk); + sk_peek_offset_bwd(sk, len); + skb_orphan(skb); + unlock_sock_fast(sk, slow); + + /* skb is now orphaned, can be freed outside of locked section */ + __kfree_skb(skb); +} +EXPORT_SYMBOL(__skb_free_datagram_locked); + +int __sk_queue_drop_skb(struct sock *sk, struct sk_buff_head *sk_queue, + struct sk_buff *skb, unsigned int flags, + void (*destructor)(struct sock *sk, + struct sk_buff *skb)) +{ + int err = 0; + + if (flags & MSG_PEEK) { + err = -ENOENT; + spin_lock_bh(&sk_queue->lock); + if (skb->next) { + __skb_unlink(skb, sk_queue); + refcount_dec(&skb->users); + if (destructor) + destructor(sk, skb); + err = 0; + } + spin_unlock_bh(&sk_queue->lock); + } + + atomic_inc(&sk->sk_drops); + return err; +} +EXPORT_SYMBOL(__sk_queue_drop_skb); + +/** + * skb_kill_datagram - Free a datagram skbuff forcibly + * @sk: socket + * @skb: datagram skbuff + * @flags: MSG\_ flags + * + * This function frees a datagram skbuff that was received by + * skb_recv_datagram. The flags argument must match the one + * used for skb_recv_datagram. + * + * If the MSG_PEEK flag is set, and the packet is still on the + * receive queue of the socket, it will be taken off the queue + * before it is freed. + * + * This function currently only disables BH when acquiring the + * sk_receive_queue lock. Therefore it must not be used in a + * context where that lock is acquired in an IRQ context. + * + * It returns 0 if the packet was removed by us. + */ + +int skb_kill_datagram(struct sock *sk, struct sk_buff *skb, unsigned int flags) +{ + int err = __sk_queue_drop_skb(sk, &sk->sk_receive_queue, skb, flags, + NULL); + + kfree_skb(skb); + return err; +} +EXPORT_SYMBOL(skb_kill_datagram); + +INDIRECT_CALLABLE_DECLARE(static size_t simple_copy_to_iter(const void *addr, + size_t bytes, + void *data __always_unused, + struct iov_iter *i)); + +static int __skb_datagram_iter(const struct sk_buff *skb, int offset, + struct iov_iter *to, int len, bool fault_short, + size_t (*cb)(const void *, size_t, void *, + struct iov_iter *), void *data) +{ + int start = skb_headlen(skb); + int i, copy = start - offset, start_off = offset, n; + struct sk_buff *frag_iter; + + /* Copy header. */ + if (copy > 0) { + if (copy > len) + copy = len; + n = INDIRECT_CALL_1(cb, simple_copy_to_iter, + skb->data + offset, copy, data, to); + offset += n; + if (n != copy) + goto short_copy; + if ((len -= copy) == 0) + return 0; + } + + /* Copy paged appendix. Hmm... why does this look so complicated? */ + for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { + int end; + const 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) { + struct page *page = skb_frag_page(frag); + u8 *vaddr = kmap(page); + + if (copy > len) + copy = len; + n = INDIRECT_CALL_1(cb, simple_copy_to_iter, + vaddr + skb_frag_off(frag) + offset - start, + copy, data, to); + kunmap(page); + offset += n; + if (n != copy) + goto short_copy; + if (!(len -= copy)) + return 0; + } + 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_datagram_iter(frag_iter, offset - start, + to, copy, fault_short, cb, data)) + goto fault; + if ((len -= copy) == 0) + return 0; + offset += copy; + } + start = end; + } + if (!len) + return 0; + + /* This is not really a user copy fault, but rather someone + * gave us a bogus length on the skb. We should probably + * print a warning here as it may indicate a kernel bug. + */ + +fault: + iov_iter_revert(to, offset - start_off); + return -EFAULT; + +short_copy: + if (fault_short || iov_iter_count(to)) + goto fault; + + return 0; +} + +/** + * skb_copy_and_hash_datagram_iter - Copy datagram to an iovec iterator + * and update a hash. + * @skb: buffer to copy + * @offset: offset in the buffer to start copying from + * @to: iovec iterator to copy to + * @len: amount of data to copy from buffer to iovec + * @hash: hash request to update + */ +int skb_copy_and_hash_datagram_iter(const struct sk_buff *skb, int offset, + struct iov_iter *to, int len, + struct ahash_request *hash) +{ + return __skb_datagram_iter(skb, offset, to, len, true, + hash_and_copy_to_iter, hash); +} +EXPORT_SYMBOL(skb_copy_and_hash_datagram_iter); + +static size_t simple_copy_to_iter(const void *addr, size_t bytes, + void *data __always_unused, struct iov_iter *i) +{ + return copy_to_iter(addr, bytes, i); +} + +/** + * skb_copy_datagram_iter - Copy a datagram to an iovec iterator. + * @skb: buffer to copy + * @offset: offset in the buffer to start copying from + * @to: iovec iterator to copy to + * @len: amount of data to copy from buffer to iovec + */ +int skb_copy_datagram_iter(const struct sk_buff *skb, int offset, + struct iov_iter *to, int len) +{ + trace_skb_copy_datagram_iovec(skb, len); + return __skb_datagram_iter(skb, offset, to, len, false, + simple_copy_to_iter, NULL); +} +EXPORT_SYMBOL(skb_copy_datagram_iter); + +/** + * skb_copy_datagram_from_iter - Copy a datagram from an iov_iter. + * @skb: buffer to copy + * @offset: offset in the buffer to start copying to + * @from: the copy source + * @len: amount of data to copy to buffer from iovec + * + * Returns 0 or -EFAULT. + */ +int skb_copy_datagram_from_iter(struct sk_buff *skb, int offset, + struct iov_iter *from, + int len) +{ + int start = skb_headlen(skb); + int i, copy = start - offset; + struct sk_buff *frag_iter; + + /* Copy header. */ + if (copy > 0) { + if (copy > len) + copy = len; + if (copy_from_iter(skb->data + offset, copy, from) != copy) + goto fault; + if ((len -= copy) == 0) + return 0; + offset += copy; + } + + /* Copy paged appendix. Hmm... why does this look so complicated? */ + for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { + int end; + const 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) { + size_t copied; + + if (copy > len) + copy = len; + copied = copy_page_from_iter(skb_frag_page(frag), + skb_frag_off(frag) + offset - start, + copy, from); + if (copied != copy) + goto fault; + + if (!(len -= copy)) + return 0; + 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) { + if (copy > len) + copy = len; + if (skb_copy_datagram_from_iter(frag_iter, + offset - start, + from, copy)) + goto fault; + if ((len -= copy) == 0) + return 0; + offset += copy; + } + start = end; + } + if (!len) + return 0; + +fault: + return -EFAULT; +} +EXPORT_SYMBOL(skb_copy_datagram_from_iter); + +int __zerocopy_sg_from_iter(struct msghdr *msg, struct sock *sk, + struct sk_buff *skb, struct iov_iter *from, + size_t length) +{ + int frag; + + if (msg && msg->msg_ubuf && msg->sg_from_iter) + return msg->sg_from_iter(sk, skb, from, length); + + frag = skb_shinfo(skb)->nr_frags; + + while (length && iov_iter_count(from)) { + struct page *pages[MAX_SKB_FRAGS]; + struct page *last_head = NULL; + size_t start; + ssize_t copied; + unsigned long truesize; + int refs, n = 0; + + if (frag == MAX_SKB_FRAGS) + return -EMSGSIZE; + + copied = iov_iter_get_pages2(from, pages, length, + MAX_SKB_FRAGS - frag, &start); + if (copied < 0) + return -EFAULT; + + length -= copied; + + truesize = PAGE_ALIGN(copied + start); + skb->data_len += copied; + skb->len += copied; + skb->truesize += truesize; + if (sk && sk->sk_type == SOCK_STREAM) { + sk_wmem_queued_add(sk, truesize); + if (!skb_zcopy_pure(skb)) + sk_mem_charge(sk, truesize); + } else { + refcount_add(truesize, &skb->sk->sk_wmem_alloc); + } + for (refs = 0; copied != 0; start = 0) { + int size = min_t(int, copied, PAGE_SIZE - start); + struct page *head = compound_head(pages[n]); + + start += (pages[n] - head) << PAGE_SHIFT; + copied -= size; + n++; + if (frag) { + skb_frag_t *last = &skb_shinfo(skb)->frags[frag - 1]; + + if (head == skb_frag_page(last) && + start == skb_frag_off(last) + skb_frag_size(last)) { + skb_frag_size_add(last, size); + /* We combined this page, we need to release + * a reference. Since compound pages refcount + * is shared among many pages, batch the refcount + * adjustments to limit false sharing. + */ + last_head = head; + refs++; + continue; + } + } + if (refs) { + page_ref_sub(last_head, refs); + refs = 0; + } + skb_fill_page_desc_noacc(skb, frag++, head, start, size); + } + if (refs) + page_ref_sub(last_head, refs); + } + return 0; +} +EXPORT_SYMBOL(__zerocopy_sg_from_iter); + +/** + * zerocopy_sg_from_iter - Build a zerocopy datagram from an iov_iter + * @skb: buffer to copy + * @from: the source to copy from + * + * The function will first copy up to headlen, and then pin the userspace + * pages and build frags through them. + * + * Returns 0, -EFAULT or -EMSGSIZE. + */ +int zerocopy_sg_from_iter(struct sk_buff *skb, struct iov_iter *from) +{ + int copy = min_t(int, skb_headlen(skb), iov_iter_count(from)); + + /* copy up to skb headlen */ + if (skb_copy_datagram_from_iter(skb, 0, from, copy)) + return -EFAULT; + + return __zerocopy_sg_from_iter(NULL, NULL, skb, from, ~0U); +} +EXPORT_SYMBOL(zerocopy_sg_from_iter); + +/** + * skb_copy_and_csum_datagram - Copy datagram to an iovec iterator + * and update a checksum. + * @skb: buffer to copy + * @offset: offset in the buffer to start copying from + * @to: iovec iterator to copy to + * @len: amount of data to copy from buffer to iovec + * @csump: checksum pointer + */ +static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset, + struct iov_iter *to, int len, + __wsum *csump) +{ + struct csum_state csdata = { .csum = *csump }; + int ret; + + ret = __skb_datagram_iter(skb, offset, to, len, true, + csum_and_copy_to_iter, &csdata); + if (ret) + return ret; + + *csump = csdata.csum; + return 0; +} + +/** + * skb_copy_and_csum_datagram_msg - Copy and checksum skb to user iovec. + * @skb: skbuff + * @hlen: hardware length + * @msg: destination + * + * Caller _must_ check that skb will fit to this iovec. + * + * Returns: 0 - success. + * -EINVAL - checksum failure. + * -EFAULT - fault during copy. + */ +int skb_copy_and_csum_datagram_msg(struct sk_buff *skb, + int hlen, struct msghdr *msg) +{ + __wsum csum; + int chunk = skb->len - hlen; + + if (!chunk) + return 0; + + if (msg_data_left(msg) < chunk) { + if (__skb_checksum_complete(skb)) + return -EINVAL; + if (skb_copy_datagram_msg(skb, hlen, msg, chunk)) + goto fault; + } else { + csum = csum_partial(skb->data, hlen, skb->csum); + if (skb_copy_and_csum_datagram(skb, hlen, &msg->msg_iter, + chunk, &csum)) + goto fault; + + if (csum_fold(csum)) { + iov_iter_revert(&msg->msg_iter, chunk); + return -EINVAL; + } + + if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) && + !skb->csum_complete_sw) + netdev_rx_csum_fault(NULL, skb); + } + return 0; +fault: + return -EFAULT; +} +EXPORT_SYMBOL(skb_copy_and_csum_datagram_msg); + +/** + * datagram_poll - generic datagram poll + * @file: file struct + * @sock: socket + * @wait: poll table + * + * Datagram poll: Again totally generic. This also handles + * sequenced packet sockets providing the socket receive queue + * is only ever holding data ready to receive. + * + * Note: when you *don't* use this routine for this protocol, + * and you use a different write policy from sock_writeable() + * then please supply your own write_space callback. + */ +__poll_t datagram_poll(struct file *file, struct socket *sock, + poll_table *wait) +{ + struct sock *sk = sock->sk; + __poll_t mask; + u8 shutdown; + + sock_poll_wait(file, sock, wait); + mask = 0; + + /* exceptional events? */ + if (READ_ONCE(sk->sk_err) || + !skb_queue_empty_lockless(&sk->sk_error_queue)) + mask |= EPOLLERR | + (sock_flag(sk, SOCK_SELECT_ERR_QUEUE) ? EPOLLPRI : 0); + + shutdown = READ_ONCE(sk->sk_shutdown); + if (shutdown & RCV_SHUTDOWN) + mask |= EPOLLRDHUP | EPOLLIN | EPOLLRDNORM; + if (shutdown == SHUTDOWN_MASK) + mask |= EPOLLHUP; + + /* readable? */ + if (!skb_queue_empty_lockless(&sk->sk_receive_queue)) + mask |= EPOLLIN | EPOLLRDNORM; + + /* Connection-based need to check for termination and startup */ + if (connection_based(sk)) { + int state = READ_ONCE(sk->sk_state); + + if (state == TCP_CLOSE) + mask |= EPOLLHUP; + /* connection hasn't started yet? */ + if (state == TCP_SYN_SENT) + return mask; + } + + /* writable? */ + if (sock_writeable(sk)) + mask |= EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND; + else + sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk); + + return mask; +} +EXPORT_SYMBOL(datagram_poll); |