| /* |
| * 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 <asm/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 <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_t *wait, unsigned int mode, int sync, |
| void *key) |
| { |
| unsigned long bits = (unsigned long)key; |
| |
| /* |
| * Avoid a wakeup if event not interesting for us |
| */ |
| if (bits && !(bits & (POLLIN | POLLERR))) |
| return 0; |
| return autoremove_wake_function(wait, mode, sync, key); |
| } |
| /* |
| * Wait for the last received packet to be different from skb |
| */ |
| static int wait_for_more_packets(struct sock *sk, 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 (sk->sk_receive_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; |
| } |
| |
| 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; |
| } |
| |
| /** |
| * __skb_recv_datagram - Receive a datagram skbuff |
| * @sk: socket |
| * @flags: MSG_ flags |
| * @peeked: returns non-zero if this packet has been seen before |
| * @off: an offset in bytes to peek skb from. Returns an offset |
| * within an skb where data actually starts |
| * @err: error code returned |
| * |
| * 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) |
| * |
| * * 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_recv_datagram(struct sock *sk, unsigned int flags, |
| int *peeked, int *off, int *err) |
| { |
| struct sk_buff_head *queue = &sk->sk_receive_queue; |
| struct sk_buff *skb, *last; |
| unsigned long cpu_flags; |
| long timeo; |
| /* |
| * Caller is allowed not to check sk->sk_err before skb_recv_datagram() |
| */ |
| int error = sock_error(sk); |
| |
| if (error) |
| goto no_packet; |
| |
| timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT); |
| |
| 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) |
| */ |
| int _off = *off; |
| |
| last = (struct sk_buff *)queue; |
| spin_lock_irqsave(&queue->lock, cpu_flags); |
| skb_queue_walk(queue, skb) { |
| last = skb; |
| *peeked = skb->peeked; |
| if (flags & MSG_PEEK) { |
| if (_off >= skb->len && (skb->len || _off || |
| skb->peeked)) { |
| _off -= skb->len; |
| continue; |
| } |
| |
| skb = skb_set_peeked(skb); |
| error = PTR_ERR(skb); |
| if (IS_ERR(skb)) |
| goto unlock_err; |
| |
| atomic_inc(&skb->users); |
| } else |
| __skb_unlink(skb, queue); |
| |
| spin_unlock_irqrestore(&queue->lock, cpu_flags); |
| *off = _off; |
| return skb; |
| } |
| spin_unlock_irqrestore(&queue->lock, cpu_flags); |
| |
| if (sk_can_busy_loop(sk) && |
| sk_busy_loop(sk, flags & MSG_DONTWAIT)) |
| continue; |
| |
| /* User doesn't want to wait */ |
| error = -EAGAIN; |
| if (!timeo) |
| goto no_packet; |
| |
| } while (!wait_for_more_packets(sk, err, &timeo, last)); |
| |
| return NULL; |
| |
| unlock_err: |
| spin_unlock_irqrestore(&queue->lock, cpu_flags); |
| no_packet: |
| *err = error; |
| return NULL; |
| } |
| EXPORT_SYMBOL(__skb_recv_datagram); |
| |
| struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned int flags, |
| int noblock, int *err) |
| { |
| int peeked, off = 0; |
| |
| return __skb_recv_datagram(sk, flags | (noblock ? MSG_DONTWAIT : 0), |
| &peeked, &off, err); |
| } |
| EXPORT_SYMBOL(skb_recv_datagram); |
| |
| void skb_free_datagram(struct sock *sk, struct sk_buff *skb) |
| { |
| consume_skb(skb); |
| sk_mem_reclaim_partial(sk); |
| } |
| EXPORT_SYMBOL(skb_free_datagram); |
| |
| void skb_free_datagram_locked(struct sock *sk, struct sk_buff *skb) |
| { |
| bool slow; |
| |
| if (likely(atomic_read(&skb->users) == 1)) |
| smp_rmb(); |
| else if (likely(!atomic_dec_and_test(&skb->users))) |
| return; |
| |
| slow = lock_sock_fast(sk); |
| skb_orphan(skb); |
| sk_mem_reclaim_partial(sk); |
| 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); |
| |
| /** |
| * 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 = 0; |
| |
| if (flags & MSG_PEEK) { |
| err = -ENOENT; |
| spin_lock_bh(&sk->sk_receive_queue.lock); |
| if (skb == skb_peek(&sk->sk_receive_queue)) { |
| __skb_unlink(skb, &sk->sk_receive_queue); |
| atomic_dec(&skb->users); |
| err = 0; |
| } |
| spin_unlock_bh(&sk->sk_receive_queue.lock); |
| } |
| |
| kfree_skb(skb); |
| atomic_inc(&sk->sk_drops); |
| sk_mem_reclaim_partial(sk); |
| |
| return err; |
| } |
| EXPORT_SYMBOL(skb_kill_datagram); |
| |
| /** |
| * 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) |
| { |
| int start = skb_headlen(skb); |
| int i, copy = start - offset; |
| struct sk_buff *frag_iter; |
| |
| trace_skb_copy_datagram_iovec(skb, len); |
| |
| /* Copy header. */ |
| if (copy > 0) { |
| if (copy > len) |
| copy = len; |
| if (copy_to_iter(skb->data + offset, copy, to) != copy) |
| goto short_copy; |
| 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) { |
| if (copy > len) |
| copy = len; |
| if (copy_page_to_iter(skb_frag_page(frag), |
| frag->page_offset + offset - |
| start, copy, to) != copy) |
| goto short_copy; |
| 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_iter(frag_iter, offset - start, |
| to, copy)) |
| 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: |
| return -EFAULT; |
| |
| short_copy: |
| if (iov_iter_count(to)) |
| goto fault; |
| |
| return 0; |
| } |
| 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), |
| frag->page_offset + 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); |
| |
| /** |
| * 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 len = iov_iter_count(from); |
| int copy = min_t(int, skb_headlen(skb), len); |
| int frag = 0; |
| |
| /* copy up to skb headlen */ |
| if (skb_copy_datagram_from_iter(skb, 0, from, copy)) |
| return -EFAULT; |
| |
| while (iov_iter_count(from)) { |
| struct page *pages[MAX_SKB_FRAGS]; |
| size_t start; |
| ssize_t copied; |
| unsigned long truesize; |
| int n = 0; |
| |
| if (frag == MAX_SKB_FRAGS) |
| return -EMSGSIZE; |
| |
| copied = iov_iter_get_pages(from, pages, ~0U, |
| MAX_SKB_FRAGS - frag, &start); |
| if (copied < 0) |
| return -EFAULT; |
| |
| iov_iter_advance(from, copied); |
| |
| truesize = PAGE_ALIGN(copied + start); |
| skb->data_len += copied; |
| skb->len += copied; |
| skb->truesize += truesize; |
| atomic_add(truesize, &skb->sk->sk_wmem_alloc); |
| while (copied) { |
| int size = min_t(int, copied, PAGE_SIZE - start); |
| skb_fill_page_desc(skb, frag++, pages[n], start, size); |
| start = 0; |
| copied -= size; |
| n++; |
| } |
| } |
| return 0; |
| } |
| EXPORT_SYMBOL(zerocopy_sg_from_iter); |
| |
| static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset, |
| struct iov_iter *to, int len, |
| __wsum *csump) |
| { |
| int start = skb_headlen(skb); |
| int i, copy = start - offset; |
| struct sk_buff *frag_iter; |
| int pos = 0; |
| int n; |
| |
| /* Copy header. */ |
| if (copy > 0) { |
| if (copy > len) |
| copy = len; |
| n = csum_and_copy_to_iter(skb->data + offset, copy, csump, to); |
| if (n != copy) |
| goto fault; |
| if ((len -= copy) == 0) |
| return 0; |
| offset += copy; |
| pos = copy; |
| } |
| |
| 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) { |
| __wsum csum2 = 0; |
| struct page *page = skb_frag_page(frag); |
| u8 *vaddr = kmap(page); |
| |
| if (copy > len) |
| copy = len; |
| n = csum_and_copy_to_iter(vaddr + frag->page_offset + |
| offset - start, copy, |
| &csum2, to); |
| kunmap(page); |
| if (n != copy) |
| goto fault; |
| *csump = csum_block_add(*csump, csum2, pos); |
| if (!(len -= copy)) |
| return 0; |
| offset += copy; |
| pos += 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 = 0; |
| if (copy > len) |
| copy = len; |
| if (skb_copy_and_csum_datagram(frag_iter, |
| offset - start, |
| to, copy, |
| &csum2)) |
| goto fault; |
| *csump = csum_block_add(*csump, csum2, pos); |
| if ((len -= copy) == 0) |
| return 0; |
| offset += copy; |
| pos += copy; |
| } |
| start = end; |
| } |
| if (!len) |
| return 0; |
| |
| fault: |
| return -EFAULT; |
| } |
| |
| __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len) |
| { |
| __sum16 sum; |
| |
| sum = csum_fold(skb_checksum(skb, 0, len, skb->csum)); |
| if (likely(!sum)) { |
| if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) && |
| !skb->csum_complete_sw) |
| netdev_rx_csum_fault(skb->dev); |
| } |
| if (!skb_shared(skb)) |
| skb->csum_valid = !sum; |
| return sum; |
| } |
| EXPORT_SYMBOL(__skb_checksum_complete_head); |
| |
| __sum16 __skb_checksum_complete(struct sk_buff *skb) |
| { |
| __wsum csum; |
| __sum16 sum; |
| |
| csum = skb_checksum(skb, 0, skb->len, 0); |
| |
| /* skb->csum holds pseudo checksum */ |
| sum = csum_fold(csum_add(skb->csum, csum)); |
| if (likely(!sum)) { |
| if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) && |
| !skb->csum_complete_sw) |
| netdev_rx_csum_fault(skb->dev); |
| } |
| |
| 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); |
| |
| /** |
| * 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)) |
| goto csum_error; |
| 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)) |
| goto csum_error; |
| if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE)) |
| netdev_rx_csum_fault(skb->dev); |
| } |
| return 0; |
| csum_error: |
| return -EINVAL; |
| 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. |
| */ |
| unsigned int datagram_poll(struct file *file, struct socket *sock, |
| poll_table *wait) |
| { |
| struct sock *sk = sock->sk; |
| unsigned int mask; |
| |
| sock_poll_wait(file, sk_sleep(sk), wait); |
| mask = 0; |
| |
| /* exceptional events? */ |
| if (sk->sk_err || !skb_queue_empty(&sk->sk_error_queue)) |
| mask |= POLLERR | |
| (sock_flag(sk, SOCK_SELECT_ERR_QUEUE) ? POLLPRI : 0); |
| |
| if (sk->sk_shutdown & RCV_SHUTDOWN) |
| mask |= POLLRDHUP | POLLIN | POLLRDNORM; |
| if (sk->sk_shutdown == SHUTDOWN_MASK) |
| mask |= POLLHUP; |
| |
| /* readable? */ |
| if (!skb_queue_empty(&sk->sk_receive_queue)) |
| mask |= POLLIN | POLLRDNORM; |
| |
| /* Connection-based need to check for termination and startup */ |
| if (connection_based(sk)) { |
| if (sk->sk_state == TCP_CLOSE) |
| mask |= POLLHUP; |
| /* connection hasn't started yet? */ |
| if (sk->sk_state == TCP_SYN_SENT) |
| return mask; |
| } |
| |
| /* writable? */ |
| if (sock_writeable(sk)) |
| mask |= POLLOUT | POLLWRNORM | POLLWRBAND; |
| else |
| sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk); |
| |
| return mask; |
| } |
| EXPORT_SYMBOL(datagram_poll); |