Commit b68e9f85 authored by Herbert Xu's avatar Herbert Xu Committed by Linus Torvalds

[PATCH] tcp: fix TSO cwnd caching bug

tcp_write_xmit caches the cwnd value indirectly in cwnd_quota.  When
tcp_transmit_skb reduces the cwnd because of tcp_enter_cwr, the cached
value becomes invalid.

This patch ensures that the cwnd value is always reread after each
tcp_transmit_skb call.
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 846998ae
......@@ -972,19 +972,18 @@ static int tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle)
if (unlikely(sk->sk_state == TCP_CLOSE))
return 0;
skb = sk->sk_send_head;
if (unlikely(!skb))
return 0;
tso_segs = tcp_init_tso_segs(sk, skb, mss_now);
cwnd_quota = tcp_cwnd_test(tp, skb);
if (unlikely(!cwnd_quota))
goto out;
sent_pkts = 0;
while (likely(tcp_snd_wnd_test(tp, skb, mss_now))) {
while ((skb = sk->sk_send_head)) {
tso_segs = tcp_init_tso_segs(sk, skb, mss_now);
BUG_ON(!tso_segs);
cwnd_quota = tcp_cwnd_test(tp, skb);
if (!cwnd_quota)
break;
if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now)))
break;
if (tso_segs == 1) {
if (unlikely(!tcp_nagle_test(tp, skb, mss_now,
(tcp_skb_is_last(sk, skb) ?
......@@ -1026,27 +1025,12 @@ static int tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle)
tcp_minshall_update(tp, mss_now, skb);
sent_pkts++;
/* Do not optimize this to use tso_segs. If we chopped up
* the packet above, tso_segs will no longer be valid.
*/
cwnd_quota -= tcp_skb_pcount(skb);
BUG_ON(cwnd_quota < 0);
if (!cwnd_quota)
break;
skb = sk->sk_send_head;
if (!skb)
break;
tso_segs = tcp_init_tso_segs(sk, skb, mss_now);
}
if (likely(sent_pkts)) {
tcp_cwnd_validate(sk, tp);
return 0;
}
out:
return !tp->packets_out && sk->sk_send_head;
}
......
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