On Thu, Aug 04, 2005 at 04:58:42PM -0700, Andrew Morton wrote:
>
> Thanks, Guillaume. Herbert, David is travelling and not able to do a lot
> of patchmonkeying. Could you please prepare and submit a final patch?
OK, here is the final version. It depends on the patch that David
posted earlier on in this thread. Please let me know if you need a
copy of that.
[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: Herbert Xu <[email protected]>
Cheers,
--
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <[email protected]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -972,19 +972,18 @@ static int tcp_write_xmit(struct sock *s
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 *s
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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