From f911e974deba4ecff3bb9c9aac616da8328f4a2b Mon Sep 17 00:00:00 2001 From: lucien Date: Sat, 5 Dec 2015 15:35:36 +0800 Subject: [PATCH] sctp: start t5 timer only when peer rwnd is 0 and local state is SHUTDOWN_PENDING commit 8a0d19c5ed417c78d03f4e0fa7215e58c40896d8 upstream. when A sends a data to B, then A close() and enter into SHUTDOWN_PENDING state, if B neither claim his rwnd is 0 nor send SACK for this data, A will keep retransmitting this data until t5 timeout, Max.Retrans times can't work anymore, which is bad. if B's rwnd is not 0, it should send abort after Max.Retrans times, only when B's rwnd == 0 and A's retransmitting beyonds Max.Retrans times, A will start t5 timer, which is also commit f8d960524328 ("sctp: Enforce retransmission limit during shutdown") means, but it lacks the condition peer rwnd == 0. so fix it by adding a bit (zero_window_announced) in peer to record if the last rwnd is 0. If it was, zero_window_announced will be set. and use this bit to decide if start t5 timer when local.state is SHUTDOWN_PENDING. Fixes: commit f8d960524328 ("sctp: Enforce retransmission limit during shutdown") Signed-off-by: Xin Long Signed-off-by: Marcelo Ricardo Leitner Signed-off-by: David S. Miller [bwh: Backported to 3.2: change sack_needed to bitfield as done earlier upstream] Signed-off-by: Ben Hutchings --- include/net/sctp/structs.h | 3 ++- net/sctp/outqueue.c | 1 + net/sctp/sm_statefuns.c | 3 ++- 3 files changed, 5 insertions(+), 2 deletions(-) diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h index 2cccd8280735..9069f8df7ed1 100644 --- a/include/net/sctp/structs.h +++ b/include/net/sctp/structs.h @@ -1586,7 +1586,8 @@ struct sctp_association { * : order. When DATA chunks are out of order, * : SACK's are not delayed (see Section 6). */ - __u8 sack_needed; /* Do we need to sack the peer? */ + __u8 sack_needed:1, /* Do we need to sack the peer? */ + zero_window_announced:1; __u32 sack_cnt; /* These are capabilities which our peer advertised. */ diff --git a/net/sctp/outqueue.c b/net/sctp/outqueue.c index 3dd7207d33ad..7b285462c88e 100644 --- a/net/sctp/outqueue.c +++ b/net/sctp/outqueue.c @@ -1265,6 +1265,7 @@ int sctp_outq_sack(struct sctp_outq *q, struct sctp_sackhdr *sack) */ sack_a_rwnd = ntohl(sack->a_rwnd); + asoc->peer.zero_window_announced = !sack_a_rwnd; outstanding = q->outstanding_bytes; if (outstanding < sack_a_rwnd) diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c index d02dd3c31d05..eb638dd9aef8 100644 --- a/net/sctp/sm_statefuns.c +++ b/net/sctp/sm_statefuns.c @@ -5302,7 +5302,8 @@ sctp_disposition_t sctp_sf_do_6_3_3_rtx(const struct sctp_endpoint *ep, SCTP_INC_STATS(SCTP_MIB_T3_RTX_EXPIREDS); if (asoc->overall_error_count >= asoc->max_retrans) { - if (asoc->state == SCTP_STATE_SHUTDOWN_PENDING) { + if (asoc->peer.zero_window_announced && + asoc->state == SCTP_STATE_SHUTDOWN_PENDING) { /* * We are here likely because the receiver had its rwnd * closed for a while and we have not been able to -- 2.39.2