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authorEric Dumazet <edumazet@google.com>2012-10-27 23:16:46 +0000
committerDavid S. Miller <davem@davemloft.net>2012-11-03 14:45:00 -0400
commite6c022a4fa2d2d9ca9d0a7ac3b05ad988f39fc30 (patch)
tree6dcd4e2dfc7895f33329fb16653a93f7d52f4bd7 /net/dccp
parent25b1e67921f448cdddf70042ba233ffe43d33a9c (diff)
tcp: better retrans tracking for defer-accept
For passive TCP connections using TCP_DEFER_ACCEPT facility, we incorrectly increment req->retrans each time timeout triggers while no SYNACK is sent. SYNACK are not sent for TCP_DEFER_ACCEPT that were established (for which we received the ACK from client). Only the last SYNACK is sent so that we can receive again an ACK from client, to move the req into accept queue. We plan to change this later to avoid the useless retransmit (and potential problem as this SYNACK could be lost) TCP_INFO later gives wrong information to user, claiming imaginary retransmits. Decouple req->retrans field into two independent fields : num_retrans : number of retransmit num_timeout : number of timeouts num_timeout is the counter that is incremented at each timeout, regardless of actual SYNACK being sent or not, and used to compute the exponential timeout. Introduce inet_rtx_syn_ack() helper to increment num_retrans only if ->rtx_syn_ack() succeeded. Use inet_rtx_syn_ack() from tcp_check_req() to increment num_retrans when we re-send a SYNACK in answer to a (retransmitted) SYN. Prior to this patch, we were not counting these retransmits. Change tcp_v[46]_rtx_synack() to increment TCP_MIB_RETRANSSEGS only if a synack packet was successfully queued. Reported-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Julian Anastasov <ja@ssi.bg> Cc: Vijay Subramanian <subramanian.vijay@gmail.com> Cc: Elliott Hughes <enh@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/dccp')
-rw-r--r--net/dccp/minisocks.c3
1 files changed, 1 insertions, 2 deletions
diff --git a/net/dccp/minisocks.c b/net/dccp/minisocks.c
index ea850ce35d4a..662071b249cc 100644
--- a/net/dccp/minisocks.c
+++ b/net/dccp/minisocks.c
@@ -174,8 +174,7 @@ struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
* To protect against Request floods, increment retrans
* counter (backoff, monitored by dccp_response_timer).
*/
- req->retrans++;
- req->rsk_ops->rtx_syn_ack(sk, req, NULL);
+ inet_rtx_syn_ack(sk, req);
}
/* Network Duplicate, discard packet */
return NULL;

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