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authorYuchung Cheng <ycheng@google.com>2013-04-29 08:44:51 +0000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-05-19 11:38:34 -0700
commita1d9ddb105801c4ac651314f5963ed2de45fc494 (patch)
treefc4f3eee6e39563c3c99da3540137027dad342db
parent0523cdce095dfa615f9c7308603bb11e99179e3c (diff)
tcp: reset timer after any SYNACK retransmit
[ Upstream commit cd75eff64dae8856afbf6ef0f0ca3c145465d8e0 ] Linux immediately returns SYNACK on (spurious) SYN retransmits, but keeps the SYNACK timer running independently. Thus the timer may fire right after the SYNACK retransmit and causes a SYN-SYNACK cross-fire burst. Adopt the fast retransmit/recovery idea in established state by re-arming the SYNACK timer after the fast (SYNACK) retransmit. The timer may fire late up to 500ms due to the current SYNACK timer wheel, but it's OK to be conservative when network is congested. Eric's new listener design should address this issue. Signed-off-by: Yuchung Cheng <ycheng@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--net/ipv4/tcp_minisocks.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index b83a49cc381..2f672e7ab6e 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -583,8 +583,13 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
*
* Note that even if there is new data in the SYN packet
* they will be thrown away too.
+ *
+ * Reset timer after retransmitting SYNACK, similar to
+ * the idea of fast retransmit in recovery.
*/
- inet_rtx_syn_ack(sk, req);
+ if (!inet_rtx_syn_ack(sk, req))
+ req->expires = min(TCP_TIMEOUT_INIT << req->num_timeout,
+ TCP_RTO_MAX) + jiffies;
return NULL;
}