[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: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index e118b4b..7d076f0d 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -972,19 +972,18 @@
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 @@
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;
}