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authorJulian Anastasov <ja@ssi.bg>2009-10-19 06:03:58 -0400
committerDavid S. Miller <davem@davemloft.net>2009-10-19 22:19:03 -0400
commit0c3d79bce48034018e840468ac5a642894a521a3 (patch)
tree96a56d10d55173c032aa1adc2b47a7571e4055a2
parentd1b99ba41d6c5aa1ed2fc634323449dd656899e9 (diff)
tcp: reduce SYN-ACK retrans for TCP_DEFER_ACCEPT
Change SYN-ACK retransmitting code for the TCP_DEFER_ACCEPT users to not retransmit SYN-ACKs during the deferring period if ACK from client was received. The goal is to reduce traffic during the deferring period. When the period is finished we continue with sending SYN-ACKs (at least one) but this time any traffic from client will change the request to established socket allowing application to terminate it properly. Also, do not drop acked request if sending of SYN-ACK fails. Signed-off-by: Julian Anastasov <ja@ssi.bg> Acked-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/ipv4/inet_connection_sock.c34
1 files changed, 31 insertions, 3 deletions
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 4351ca2cf0b8..537731b3bcb3 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -446,6 +446,28 @@ extern int sysctl_tcp_synack_retries;
446 446
447EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add); 447EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);
448 448
449/* Decide when to expire the request and when to resend SYN-ACK */
450static inline void syn_ack_recalc(struct request_sock *req, const int thresh,
451 const int max_retries,
452 const u8 rskq_defer_accept,
453 int *expire, int *resend)
454{
455 if (!rskq_defer_accept) {
456 *expire = req->retrans >= thresh;
457 *resend = 1;
458 return;
459 }
460 *expire = req->retrans >= thresh &&
461 (!inet_rsk(req)->acked || req->retrans >= max_retries);
462 /*
463 * Do not resend while waiting for data after ACK,
464 * start to resend on end of deferring period to give
465 * last chance for data or ACK to create established socket.
466 */
467 *resend = !inet_rsk(req)->acked ||
468 req->retrans >= rskq_defer_accept - 1;
469}
470
449void inet_csk_reqsk_queue_prune(struct sock *parent, 471void inet_csk_reqsk_queue_prune(struct sock *parent,
450 const unsigned long interval, 472 const unsigned long interval,
451 const unsigned long timeout, 473 const unsigned long timeout,
@@ -501,9 +523,15 @@ void inet_csk_reqsk_queue_prune(struct sock *parent,
501 reqp=&lopt->syn_table[i]; 523 reqp=&lopt->syn_table[i];
502 while ((req = *reqp) != NULL) { 524 while ((req = *reqp) != NULL) {
503 if (time_after_eq(now, req->expires)) { 525 if (time_after_eq(now, req->expires)) {
504 if ((req->retrans < thresh || 526 int expire = 0, resend = 0;
505 (inet_rsk(req)->acked && req->retrans < max_retries)) 527
506 && !req->rsk_ops->rtx_syn_ack(parent, req)) { 528 syn_ack_recalc(req, thresh, max_retries,
529 queue->rskq_defer_accept,
530 &expire, &resend);
531 if (!expire &&
532 (!resend ||
533 !req->rsk_ops->rtx_syn_ack(parent, req) ||
534 inet_rsk(req)->acked)) {
507 unsigned long timeo; 535 unsigned long timeo;
508 536
509 if (req->retrans++ == 0) 537 if (req->retrans++ == 0)