tcp: fix incorrect ca_state in tail loss probe
authorYuchung Cheng <ycheng@google.com>
Sat, 12 Oct 2013 17:16:27 +0000 (10:16 -0700)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Mon, 4 Nov 2013 12:30:59 +0000 (04:30 -0800)
commitd8ac0f178f98d4e7c23cf9526d789d4869ec6e4c
tree53683235baffd5c8b47c4df221a904b8d471e236
parenta50b0399e6899e39e6f74431aaddf12ee92db854
tcp: fix incorrect ca_state in tail loss probe

[ Upstream commit 031afe4990a7c9dbff41a3a742c44d3e740ea0a1 ]

On receiving an ACK that covers the loss probe sequence, TLP
immediately sets the congestion state to Open, even though some packets
are not recovered and retransmisssion are on the way.  The later ACks
may trigger a WARN_ON check in step D of tcp_fastretrans_alert(), e.g.,
https://bugzilla.redhat.com/show_bug.cgi?id=989251

The fix is to follow the similar procedure in recovery by calling
tcp_try_keep_open(). The sender switches to Open state if no packets
are retransmissted. Otherwise it goes to Disorder and let subsequent
ACKs move the state to Recovery or Open.

Reported-By: Michael Sterrett <michael@sterretts.net>
Tested-By: Dormando <dormando@rydia.net>
Signed-off-by: Yuchung Cheng <ycheng@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>
net/ipv4/tcp_input.c