From e11ecddf5128011c936cc5360780190cbc901fdc Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Mon, 15 Sep 2014 04:19:51 -0700 Subject: tcp: use TCP_SKB_CB(skb)->tcp_flags in input path Input path of TCP do not currently uses TCP_SKB_CB(skb)->tcp_flags, which is only used in output path. tcp_recvmsg(), looks at tcp_hdr(skb)->syn for every skb found in receive queue, and its unfortunate because this bit is located in a cache line right before the payload. We can simplify TCP by copying tcp flags into TCP_SKB_CB(skb)->tcp_flags. This patch does so, and avoids the cache line miss in tcp_recvmsg() Following patches will - allow a segment with FIN being coalesced in tcp_try_coalesce() - simplify tcp_collapse() by not copying the headers. Signed-off-by: Eric Dumazet Acked-by: Neal Cardwell Signed-off-by: David S. Miller --- net/ipv4/tcp.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) (limited to 'net/ipv4/tcp.c') diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 541f26a67ba2..070aeff1b131 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1510,9 +1510,9 @@ static struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off) while ((skb = skb_peek(&sk->sk_receive_queue)) != NULL) { offset = seq - TCP_SKB_CB(skb)->seq; - if (tcp_hdr(skb)->syn) + if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) offset--; - if (offset < skb->len || tcp_hdr(skb)->fin) { + if (offset < skb->len || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) { *off = offset; return skb; } @@ -1585,7 +1585,7 @@ int tcp_read_sock(struct sock *sk, read_descriptor_t *desc, if (offset + 1 != skb->len) continue; } - if (tcp_hdr(skb)->fin) { + if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) { sk_eat_skb(sk, skb, false); ++seq; break; @@ -1722,11 +1722,11 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, break; offset = *seq - TCP_SKB_CB(skb)->seq; - if (tcp_hdr(skb)->syn) + if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) offset--; if (offset < skb->len) goto found_ok_skb; - if (tcp_hdr(skb)->fin) + if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) goto found_fin_ok; WARN(!(flags & MSG_PEEK), "recvmsg bug 2: copied %X seq %X rcvnxt %X fl %X\n", @@ -1959,7 +1959,7 @@ skip_copy: if (used + offset < skb->len) continue; - if (tcp_hdr(skb)->fin) + if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) goto found_fin_ok; if (!(flags & MSG_PEEK)) { sk_eat_skb(sk, skb, copied_early); @@ -2160,8 +2160,10 @@ void tcp_close(struct sock *sk, long timeout) * reader process may not have drained the data yet! */ while ((skb = __skb_dequeue(&sk->sk_receive_queue)) != NULL) { - u32 len = TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq - - tcp_hdr(skb)->fin; + u32 len = TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq; + + if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) + len--; data_was_unread += len; __kfree_skb(skb); } -- cgit v1.2.3-59-g8ed1b