From e11ecddf5128011c936cc5360780190cbc901fdc Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Mon, 15 Sep 2014 04:19:51 -0700 Subject: [PATCH] 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 ++++++++++-------- net/ipv4/tcp_input.c | 10 +++++----- net/ipv4/tcp_ipv4.c | 1 + net/ipv6/tcp_ipv6.c | 1 + 4 files changed, 17 insertions(+), 13 deletions(-) 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); } diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index f97003ad0af5..8f639a4face9 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4093,7 +4093,7 @@ static void tcp_ofo_queue(struct sock *sk) __skb_unlink(skb, &tp->out_of_order_queue); __skb_queue_tail(&sk->sk_receive_queue, skb); tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq; - if (tcp_hdr(skb)->fin) + if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) tcp_fin(sk); } } @@ -4513,7 +4513,7 @@ restart: * - bloated or contains data before "start" or * overlaps to the next one. */ - if (!tcp_hdr(skb)->syn && !tcp_hdr(skb)->fin && + if (!(TCP_SKB_CB(skb)->tcp_flags & (TCPHDR_SYN | TCPHDR_FIN)) && (tcp_win_from_space(skb->truesize) > skb->len || before(TCP_SKB_CB(skb)->seq, start))) { end_of_skbs = false; @@ -4532,7 +4532,8 @@ restart: /* Decided to skip this, advance start seq. */ start = TCP_SKB_CB(skb)->end_seq; } - if (end_of_skbs || tcp_hdr(skb)->syn || tcp_hdr(skb)->fin) + if (end_of_skbs || + (TCP_SKB_CB(skb)->tcp_flags & (TCPHDR_SYN | TCPHDR_FIN))) return; while (before(start, end)) { @@ -4579,8 +4580,7 @@ restart: skb = tcp_collapse_one(sk, skb, list); if (!skb || skb == tail || - tcp_hdr(skb)->syn || - tcp_hdr(skb)->fin) + (TCP_SKB_CB(skb)->tcp_flags & (TCPHDR_SYN | TCPHDR_FIN))) return; } } diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 7881b96d2b72..006b045716d8 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1638,6 +1638,7 @@ int tcp_v4_rcv(struct sk_buff *skb) TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin + skb->len - th->doff * 4); TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq); + TCP_SKB_CB(skb)->tcp_flags = tcp_flag_byte(th); TCP_SKB_CB(skb)->tcp_tw_isn = 0; TCP_SKB_CB(skb)->ip_dsfield = ipv4_get_dsfield(iph); TCP_SKB_CB(skb)->sacked = 0; diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 1835480336ac..de51a88bec6f 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -1415,6 +1415,7 @@ static int tcp_v6_rcv(struct sk_buff *skb) TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin + skb->len - th->doff*4); TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq); + TCP_SKB_CB(skb)->tcp_flags = tcp_flag_byte(th); TCP_SKB_CB(skb)->tcp_tw_isn = 0; TCP_SKB_CB(skb)->ip_dsfield = ipv6_get_dsfield(hdr); TCP_SKB_CB(skb)->sacked = 0; -- 2.20.1