From: David S. Miller Date: Fri, 5 Aug 2005 02:52:01 +0000 (-0700) Subject: [PATCH] tcp: fix TSO sizing bugs X-Git-Tag: v2.6.13-rc6~38 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=846998ae87a80b0fd45b4cf5cf001a159d746f27;p=linux-2.6 [PATCH] tcp: fix TSO sizing bugs MSS changes can be lost since we preemptively initialize the tso_segs count for an SKB before we %100 commit to sending it out. So, by the time we send it out, the tso_size information can be stale due to PMTU events. This mucks up all of the logic in our send engine, and can even result in the BUG() triggering in tcp_tso_should_defer(). Another problem we have is that we're storing the tp->mss_cache, not the SACK block normalized MSS, as the tso_size. That's wrong too. Signed-off-by: David S. Miller Cc: Herbert Xu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index e3f8ea1bfa..e118b4b5b3 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -403,11 +403,9 @@ static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) sk->sk_send_head = skb; } -static void tcp_set_skb_tso_segs(struct sock *sk, struct sk_buff *skb) +static void tcp_set_skb_tso_segs(struct sock *sk, struct sk_buff *skb, unsigned int mss_now) { - struct tcp_sock *tp = tcp_sk(sk); - - if (skb->len <= tp->mss_cache || + if (skb->len <= mss_now || !(sk->sk_route_caps & NETIF_F_TSO)) { /* Avoid the costly divide in the normal * non-TSO case. @@ -417,10 +415,10 @@ static void tcp_set_skb_tso_segs(struct sock *sk, struct sk_buff *skb) } else { unsigned int factor; - factor = skb->len + (tp->mss_cache - 1); - factor /= tp->mss_cache; + factor = skb->len + (mss_now - 1); + factor /= mss_now; skb_shinfo(skb)->tso_segs = factor; - skb_shinfo(skb)->tso_size = tp->mss_cache; + skb_shinfo(skb)->tso_size = mss_now; } } @@ -429,7 +427,7 @@ static void tcp_set_skb_tso_segs(struct sock *sk, struct sk_buff *skb) * packet to the list. This won't be called frequently, I hope. * Remember, these are still headerless SKBs at this point. */ -static int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len) +static int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, unsigned int mss_now) { struct tcp_sock *tp = tcp_sk(sk); struct sk_buff *buff; @@ -492,8 +490,8 @@ static int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len) } /* Fix up tso_factor for both original and new SKB. */ - tcp_set_skb_tso_segs(sk, skb); - tcp_set_skb_tso_segs(sk, buff); + tcp_set_skb_tso_segs(sk, skb, mss_now); + tcp_set_skb_tso_segs(sk, buff, mss_now); if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) { tp->lost_out += tcp_skb_pcount(skb); @@ -569,7 +567,7 @@ int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len) * factor and mss. */ if (tcp_skb_pcount(skb) > 1) - tcp_set_skb_tso_segs(sk, skb); + tcp_set_skb_tso_segs(sk, skb, tcp_current_mss(sk, 1)); return 0; } @@ -734,12 +732,14 @@ static inline unsigned int tcp_cwnd_test(struct tcp_sock *tp, struct sk_buff *sk /* This must be invoked the first time we consider transmitting * SKB onto the wire. */ -static inline int tcp_init_tso_segs(struct sock *sk, struct sk_buff *skb) +static inline int tcp_init_tso_segs(struct sock *sk, struct sk_buff *skb, unsigned int mss_now) { int tso_segs = tcp_skb_pcount(skb); - if (!tso_segs) { - tcp_set_skb_tso_segs(sk, skb); + if (!tso_segs || + (tso_segs > 1 && + skb_shinfo(skb)->tso_size != mss_now)) { + tcp_set_skb_tso_segs(sk, skb, mss_now); tso_segs = tcp_skb_pcount(skb); } return tso_segs; @@ -817,7 +817,7 @@ static unsigned int tcp_snd_test(struct sock *sk, struct sk_buff *skb, struct tcp_sock *tp = tcp_sk(sk); unsigned int cwnd_quota; - tcp_init_tso_segs(sk, skb); + tcp_init_tso_segs(sk, skb, cur_mss); if (!tcp_nagle_test(tp, skb, cur_mss, nonagle)) return 0; @@ -854,7 +854,7 @@ int tcp_may_send_now(struct sock *sk, struct tcp_sock *tp) * know that all the data is in scatter-gather pages, and that the * packet has never been sent out before (and thus is not cloned). */ -static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len) +static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len, unsigned int mss_now) { struct sk_buff *buff; int nlen = skb->len - len; @@ -887,8 +887,8 @@ static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len) skb_split(skb, buff, len); /* Fix up tso_factor for both original and new SKB. */ - tcp_set_skb_tso_segs(sk, skb); - tcp_set_skb_tso_segs(sk, buff); + tcp_set_skb_tso_segs(sk, skb, mss_now); + tcp_set_skb_tso_segs(sk, buff, mss_now); /* Link BUFF into the send queue. */ skb_header_release(buff); @@ -976,7 +976,7 @@ static int tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle) if (unlikely(!skb)) return 0; - tso_segs = tcp_init_tso_segs(sk, skb); + tso_segs = tcp_init_tso_segs(sk, skb, mss_now); cwnd_quota = tcp_cwnd_test(tp, skb); if (unlikely(!cwnd_quota)) goto out; @@ -1006,11 +1006,11 @@ static int tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle) limit = skb->len - trim; } if (skb->len > limit) { - if (tso_fragment(sk, skb, limit)) + if (tso_fragment(sk, skb, limit, mss_now)) break; } } else if (unlikely(skb->len > mss_now)) { - if (unlikely(tcp_fragment(sk, skb, mss_now))) + if (unlikely(tcp_fragment(sk, skb, mss_now, mss_now))) break; } @@ -1039,7 +1039,7 @@ static int tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle) skb = sk->sk_send_head; if (!skb) break; - tso_segs = tcp_init_tso_segs(sk, skb); + tso_segs = tcp_init_tso_segs(sk, skb, mss_now); } if (likely(sent_pkts)) { @@ -1076,7 +1076,7 @@ void tcp_push_one(struct sock *sk, unsigned int mss_now) BUG_ON(!skb || skb->len < mss_now); - tso_segs = tcp_init_tso_segs(sk, skb); + tso_segs = tcp_init_tso_segs(sk, skb, mss_now); cwnd_quota = tcp_snd_test(sk, skb, mss_now, TCP_NAGLE_PUSH); if (likely(cwnd_quota)) { @@ -1093,11 +1093,11 @@ void tcp_push_one(struct sock *sk, unsigned int mss_now) limit = skb->len - trim; } if (skb->len > limit) { - if (unlikely(tso_fragment(sk, skb, limit))) + if (unlikely(tso_fragment(sk, skb, limit, mss_now))) return; } } else if (unlikely(skb->len > mss_now)) { - if (unlikely(tcp_fragment(sk, skb, mss_now))) + if (unlikely(tcp_fragment(sk, skb, mss_now, mss_now))) return; } @@ -1388,7 +1388,7 @@ int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) int old_factor = tcp_skb_pcount(skb); int new_factor; - if (tcp_fragment(sk, skb, cur_mss)) + if (tcp_fragment(sk, skb, cur_mss, cur_mss)) return -ENOMEM; /* We'll try again later. */ /* New SKB created, account for it. */ @@ -1991,7 +1991,7 @@ int tcp_write_wakeup(struct sock *sk) skb->len > mss) { seg_size = min(seg_size, mss); TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_PSH; - if (tcp_fragment(sk, skb, seg_size)) + if (tcp_fragment(sk, skb, seg_size, mss)) return -1; /* SWS override triggered forced fragmentation. * Disable TSO, the connection is too sick. */ @@ -2000,7 +2000,7 @@ int tcp_write_wakeup(struct sock *sk) sk->sk_route_caps &= ~NETIF_F_TSO; } } else if (!tcp_skb_pcount(skb)) - tcp_set_skb_tso_segs(sk, skb); + tcp_set_skb_tso_segs(sk, skb, mss); TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_PSH; TCP_SKB_CB(skb)->when = tcp_time_stamp;