This is a note to let you know that I've just added the patch titled sctp: fix the transports round robin issue when init is retransmitted to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: sctp-fix-the-transports-round-robin-issue-when-init-is-retransmitted.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 39d2adebf137de5f900843f69f5e500932e31047 Mon Sep 17 00:00:00 2001 From: Xin Long <lucien.xin@xxxxxxxxx> Date: Thu, 10 Mar 2016 15:31:57 +0800 Subject: sctp: fix the transports round robin issue when init is retransmitted From: Xin Long <lucien.xin@xxxxxxxxx> commit 39d2adebf137de5f900843f69f5e500932e31047 upstream. prior to this patch, at the beginning if we have two paths in one assoc, they may have the same params other than the last_time_heard, it will try the paths like this: 1st cycle try trans1 fail. then trans2 is selected.(cause it's last_time_heard is after trans1). 2nd cycle: try trans2 fail then trans2 is selected.(cause it's last_time_heard is after trans1). 3rd cycle: try trans2 fail then trans2 is selected.(cause it's last_time_heard is after trans1). .... trans1 will never have change to be selected, which is not what we expect. we should keeping round robin all the paths if they are just added at the beginning. So at first every tranport's last_time_heard should be initialized 0, so that we ensure they have the same value at the beginning, only by this, all the transports could get equal chance to be selected. Then for sctp_trans_elect_best, it should return the trans_next one when *trans == *trans_next, so that we can try next if it fails, but now it always return trans. so we can fix it by exchanging these two params when we calls sctp_trans_elect_tie(). Fixes: 4c47af4d5eb2 ('net: sctp: rework multihoming retransmission path selection to rfc4960') Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx> Acked-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx> Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@xxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/sctp/associola.c | 2 +- net/sctp/transport.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) --- a/net/sctp/associola.c +++ b/net/sctp/associola.c @@ -1290,7 +1290,7 @@ static struct sctp_transport *sctp_trans if (score_curr > score_best) return curr; else if (score_curr == score_best) - return sctp_trans_elect_tie(curr, best); + return sctp_trans_elect_tie(best, curr); else return best; } --- a/net/sctp/transport.c +++ b/net/sctp/transport.c @@ -72,7 +72,7 @@ static struct sctp_transport *sctp_trans */ peer->rto = msecs_to_jiffies(net->sctp.rto_initial); - peer->last_time_heard = ktime_get(); + peer->last_time_heard = ktime_set(0, 0); peer->last_time_ecne_reduced = jiffies; peer->param_flags = SPP_HB_DISABLE | Patches currently in stable-queue which might be from lucien.xin@xxxxxxxxx are queue-4.4/sctp-fix-the-transports-round-robin-issue-when-init-is-retransmitted.patch