ip: convert tcp_sendmsg() to iov_iter primitives
patch is actually smaller than it seems to be - most of it is unindenting the inner loop body in tcp_sendmsg() itself... the bit in tcp_input.c is going to get reverted very soon - that's what memcpy_from_msg() will become, but not in this commit; let's keep it reasonably contained... There's one potentially subtle change here: in case of short copy from userland, mainline tcp_send_syn_data() discards the skb it has allocated and falls back to normal path, where we'll send as much as possible after rereading the same data again. This patch trims SYN+data skb instead - that way we don't need to copy from the same place twice. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro
241
net/ipv4/tcp.c
241
net/ipv4/tcp.c
@@ -1067,11 +1067,10 @@ static int tcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg,
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int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
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size_t size)
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{
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const struct iovec *iov;
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struct tcp_sock *tp = tcp_sk(sk);
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struct sk_buff *skb;
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int iovlen, flags, err, copied = 0;
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int mss_now = 0, size_goal, copied_syn = 0, offset = 0;
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int flags, err, copied = 0;
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int mss_now = 0, size_goal, copied_syn = 0;
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bool sg;
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long timeo;
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@@ -1084,7 +1083,6 @@ int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
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goto out;
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else if (err)
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goto out_err;
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offset = copied_syn;
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}
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timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
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@@ -1118,8 +1116,6 @@ int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
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mss_now = tcp_send_mss(sk, &size_goal, flags);
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/* Ok commence sending. */
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iovlen = msg->msg_iter.nr_segs;
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iov = msg->msg_iter.iov;
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copied = 0;
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err = -EPIPE;
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@@ -1128,151 +1124,134 @@ int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
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sg = !!(sk->sk_route_caps & NETIF_F_SG);
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while (--iovlen >= 0) {
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size_t seglen = iov->iov_len;
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unsigned char __user *from = iov->iov_base;
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while (iov_iter_count(&msg->msg_iter)) {
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int copy = 0;
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int max = size_goal;
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iov++;
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if (unlikely(offset > 0)) { /* Skip bytes copied in SYN */
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if (offset >= seglen) {
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offset -= seglen;
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continue;
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}
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seglen -= offset;
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from += offset;
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offset = 0;
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skb = tcp_write_queue_tail(sk);
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if (tcp_send_head(sk)) {
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if (skb->ip_summed == CHECKSUM_NONE)
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max = mss_now;
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copy = max - skb->len;
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}
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while (seglen > 0) {
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int copy = 0;
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int max = size_goal;
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skb = tcp_write_queue_tail(sk);
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if (tcp_send_head(sk)) {
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if (skb->ip_summed == CHECKSUM_NONE)
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max = mss_now;
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copy = max - skb->len;
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}
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if (copy <= 0) {
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if (copy <= 0) {
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new_segment:
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/* Allocate new segment. If the interface is SG,
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* allocate skb fitting to single page.
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*/
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if (!sk_stream_memory_free(sk))
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goto wait_for_sndbuf;
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/* Allocate new segment. If the interface is SG,
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* allocate skb fitting to single page.
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*/
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if (!sk_stream_memory_free(sk))
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goto wait_for_sndbuf;
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skb = sk_stream_alloc_skb(sk,
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select_size(sk, sg),
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sk->sk_allocation);
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if (!skb)
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goto wait_for_memory;
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skb = sk_stream_alloc_skb(sk,
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select_size(sk, sg),
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sk->sk_allocation);
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if (!skb)
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goto wait_for_memory;
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/*
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* Check whether we can use HW checksum.
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*/
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if (sk->sk_route_caps & NETIF_F_ALL_CSUM)
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skb->ip_summed = CHECKSUM_PARTIAL;
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/*
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* Check whether we can use HW checksum.
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*/
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if (sk->sk_route_caps & NETIF_F_ALL_CSUM)
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skb->ip_summed = CHECKSUM_PARTIAL;
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skb_entail(sk, skb);
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copy = size_goal;
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max = size_goal;
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skb_entail(sk, skb);
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copy = size_goal;
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max = size_goal;
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/* All packets are restored as if they have
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* already been sent. skb_mstamp isn't set to
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* avoid wrong rtt estimation.
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*/
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if (tp->repair)
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TCP_SKB_CB(skb)->sacked |= TCPCB_REPAIRED;
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}
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/* All packets are restored as if they have
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* already been sent. skb_mstamp isn't set to
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* avoid wrong rtt estimation.
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*/
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if (tp->repair)
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TCP_SKB_CB(skb)->sacked |= TCPCB_REPAIRED;
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}
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/* Try to append data to the end of skb. */
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if (copy > seglen)
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copy = seglen;
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/* Try to append data to the end of skb. */
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if (copy > iov_iter_count(&msg->msg_iter))
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copy = iov_iter_count(&msg->msg_iter);
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/* Where to copy to? */
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if (skb_availroom(skb) > 0) {
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/* We have some space in skb head. Superb! */
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copy = min_t(int, copy, skb_availroom(skb));
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err = skb_add_data_nocache(sk, skb, from, copy);
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if (err)
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goto do_fault;
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} else {
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bool merge = true;
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int i = skb_shinfo(skb)->nr_frags;
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struct page_frag *pfrag = sk_page_frag(sk);
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/* Where to copy to? */
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if (skb_availroom(skb) > 0) {
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/* We have some space in skb head. Superb! */
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copy = min_t(int, copy, skb_availroom(skb));
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err = skb_add_data_nocache(sk, skb, &msg->msg_iter, copy);
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if (err)
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goto do_fault;
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} else {
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bool merge = true;
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int i = skb_shinfo(skb)->nr_frags;
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struct page_frag *pfrag = sk_page_frag(sk);
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if (!sk_page_frag_refill(sk, pfrag))
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goto wait_for_memory;
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if (!sk_page_frag_refill(sk, pfrag))
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goto wait_for_memory;
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if (!skb_can_coalesce(skb, i, pfrag->page,
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pfrag->offset)) {
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if (i == MAX_SKB_FRAGS || !sg) {
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tcp_mark_push(tp, skb);
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goto new_segment;
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}
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merge = false;
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if (!skb_can_coalesce(skb, i, pfrag->page,
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pfrag->offset)) {
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if (i == MAX_SKB_FRAGS || !sg) {
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tcp_mark_push(tp, skb);
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goto new_segment;
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}
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copy = min_t(int, copy, pfrag->size - pfrag->offset);
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if (!sk_wmem_schedule(sk, copy))
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goto wait_for_memory;
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err = skb_copy_to_page_nocache(sk, from, skb,
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pfrag->page,
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pfrag->offset,
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copy);
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if (err)
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goto do_error;
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/* Update the skb. */
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if (merge) {
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skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
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} else {
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skb_fill_page_desc(skb, i, pfrag->page,
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pfrag->offset, copy);
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get_page(pfrag->page);
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}
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pfrag->offset += copy;
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merge = false;
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}
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if (!copied)
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TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_PSH;
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copy = min_t(int, copy, pfrag->size - pfrag->offset);
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tp->write_seq += copy;
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TCP_SKB_CB(skb)->end_seq += copy;
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tcp_skb_pcount_set(skb, 0);
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if (!sk_wmem_schedule(sk, copy))
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goto wait_for_memory;
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from += copy;
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copied += copy;
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if ((seglen -= copy) == 0 && iovlen == 0) {
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tcp_tx_timestamp(sk, skb);
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goto out;
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}
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if (skb->len < max || (flags & MSG_OOB) || unlikely(tp->repair))
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continue;
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if (forced_push(tp)) {
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tcp_mark_push(tp, skb);
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__tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH);
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} else if (skb == tcp_send_head(sk))
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tcp_push_one(sk, mss_now);
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continue;
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wait_for_sndbuf:
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set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
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wait_for_memory:
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if (copied)
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tcp_push(sk, flags & ~MSG_MORE, mss_now,
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TCP_NAGLE_PUSH, size_goal);
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if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
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err = skb_copy_to_page_nocache(sk, &msg->msg_iter, skb,
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pfrag->page,
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pfrag->offset,
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copy);
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if (err)
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goto do_error;
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mss_now = tcp_send_mss(sk, &size_goal, flags);
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/* Update the skb. */
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if (merge) {
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skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
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} else {
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skb_fill_page_desc(skb, i, pfrag->page,
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pfrag->offset, copy);
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get_page(pfrag->page);
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}
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pfrag->offset += copy;
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}
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if (!copied)
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TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_PSH;
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tp->write_seq += copy;
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TCP_SKB_CB(skb)->end_seq += copy;
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tcp_skb_pcount_set(skb, 0);
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copied += copy;
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if (!iov_iter_count(&msg->msg_iter)) {
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tcp_tx_timestamp(sk, skb);
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goto out;
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}
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if (skb->len < max || (flags & MSG_OOB) || unlikely(tp->repair))
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continue;
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if (forced_push(tp)) {
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tcp_mark_push(tp, skb);
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__tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_PUSH);
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} else if (skb == tcp_send_head(sk))
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tcp_push_one(sk, mss_now);
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continue;
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wait_for_sndbuf:
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set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
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wait_for_memory:
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if (copied)
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tcp_push(sk, flags & ~MSG_MORE, mss_now,
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TCP_NAGLE_PUSH, size_goal);
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if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
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goto do_error;
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mss_now = tcp_send_mss(sk, &size_goal, flags);
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}
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out:
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