From d5ac99a648b8c61d0c7f1c32a8ab7f1dca0123d2 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Sun, 24 Apr 2005 19:12:33 -0700 Subject: [PATCH] [TCP]: skb pcount with MTU discovery The problem is that when doing MTU discovery, the too-large segments in the write queue will be calculated as having a pcount of >1. When tcp_write_xmit() is trying to send, tcp_snd_test() fails the cwnd test when pcount > cwnd. The segments are eventually transmitted one at a time by keepalive, but this can take a long time. This patch checks if TSO is enabled when setting pcount. Signed-off-by: John Heffner Signed-off-by: David S. Miller --- include/net/tcp.h | 11 ++++++----- net/ipv4/tcp_output.c | 25 ++++++++++++++----------- 2 files changed, 20 insertions(+), 16 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index 503810a70e21..9355ae5b1d75 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1417,19 +1417,20 @@ tcp_nagle_check(const struct tcp_sock *tp, const struct sk_buff *skb, tcp_minshall_check(tp)))); } -extern void tcp_set_skb_tso_segs(struct sk_buff *, unsigned int); +extern void tcp_set_skb_tso_segs(struct sock *, struct sk_buff *); /* This checks if the data bearing packet SKB (usually sk->sk_send_head) * should be put on the wire right now. */ -static __inline__ int tcp_snd_test(const struct tcp_sock *tp, +static __inline__ int tcp_snd_test(struct sock *sk, struct sk_buff *skb, unsigned cur_mss, int nonagle) { + struct tcp_sock *tp = tcp_sk(sk); int pkts = tcp_skb_pcount(skb); if (!pkts) { - tcp_set_skb_tso_segs(skb, tp->mss_cache_std); + tcp_set_skb_tso_segs(sk, skb); pkts = tcp_skb_pcount(skb); } @@ -1490,7 +1491,7 @@ static __inline__ void __tcp_push_pending_frames(struct sock *sk, if (skb) { if (!tcp_skb_is_last(sk, skb)) nonagle = TCP_NAGLE_PUSH; - if (!tcp_snd_test(tp, skb, cur_mss, nonagle) || + if (!tcp_snd_test(sk, skb, cur_mss, nonagle) || tcp_write_xmit(sk, nonagle)) tcp_check_probe_timer(sk, tp); } @@ -1508,7 +1509,7 @@ static __inline__ int tcp_may_send_now(struct sock *sk, struct tcp_sock *tp) struct sk_buff *skb = sk->sk_send_head; return (skb && - tcp_snd_test(tp, skb, tcp_current_mss(sk, 1), + tcp_snd_test(sk, skb, tcp_current_mss(sk, 1), tcp_skb_is_last(sk, skb) ? TCP_NAGLE_PUSH : tp->nonagle)); } diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 13c14cb6dee4..a12df6979ffd 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -427,7 +427,7 @@ void tcp_push_one(struct sock *sk, unsigned cur_mss) struct tcp_sock *tp = tcp_sk(sk); struct sk_buff *skb = sk->sk_send_head; - if (tcp_snd_test(tp, skb, cur_mss, TCP_NAGLE_PUSH)) { + if (tcp_snd_test(sk, skb, cur_mss, TCP_NAGLE_PUSH)) { /* Send it out now. */ TCP_SKB_CB(skb)->when = tcp_time_stamp; tcp_tso_set_push(skb); @@ -440,9 +440,12 @@ void tcp_push_one(struct sock *sk, unsigned cur_mss) } } -void tcp_set_skb_tso_segs(struct sk_buff *skb, unsigned int mss_std) +void tcp_set_skb_tso_segs(struct sock *sk, struct sk_buff *skb) { - if (skb->len <= mss_std) { + struct tcp_sock *tp = tcp_sk(sk); + + if (skb->len <= tp->mss_cache_std || + !(sk->sk_route_caps & NETIF_F_TSO)) { /* Avoid the costly divide in the normal * non-TSO case. */ @@ -451,10 +454,10 @@ void tcp_set_skb_tso_segs(struct sk_buff *skb, unsigned int mss_std) } else { unsigned int factor; - factor = skb->len + (mss_std - 1); - factor /= mss_std; + factor = skb->len + (tp->mss_cache_std - 1); + factor /= tp->mss_cache_std; skb_shinfo(skb)->tso_segs = factor; - skb_shinfo(skb)->tso_size = mss_std; + skb_shinfo(skb)->tso_size = tp->mss_cache_std; } } @@ -525,8 +528,8 @@ 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(skb, tp->mss_cache_std); - tcp_set_skb_tso_segs(buff, tp->mss_cache_std); + tcp_set_skb_tso_segs(sk, skb); + tcp_set_skb_tso_segs(sk, buff); if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) { tp->lost_out += tcp_skb_pcount(skb); @@ -601,7 +604,7 @@ 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(skb, tcp_skb_mss(skb)); + tcp_set_skb_tso_segs(sk, skb); return 0; } @@ -752,7 +755,7 @@ int tcp_write_xmit(struct sock *sk, int nonagle) mss_now = tcp_current_mss(sk, 1); while ((skb = sk->sk_send_head) && - tcp_snd_test(tp, skb, mss_now, + tcp_snd_test(sk, skb, mss_now, tcp_skb_is_last(sk, skb) ? nonagle : TCP_NAGLE_PUSH)) { if (skb->len > mss_now) { @@ -1676,7 +1679,7 @@ int tcp_write_wakeup(struct sock *sk) tp->mss_cache = tp->mss_cache_std; } } else if (!tcp_skb_pcount(skb)) - tcp_set_skb_tso_segs(skb, tp->mss_cache_std); + tcp_set_skb_tso_segs(sk, skb); TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_PSH; TCP_SKB_CB(skb)->when = tcp_time_stamp;