From 0ce294d88457bccd7f9991f883fec80022a1ddbd Mon Sep 17 00:00:00 2001 From: Yuchung Cheng Date: Thu, 7 Dec 2017 11:33:30 -0800 Subject: [PATCH] tcp: correctly test congestion state in RACK RACK does not test the loss recovery state correctly to compute the reordering window. It assumes if lost_out is zero then TCP is not in loss recovery. But it can be zero during recovery before calling tcp_rack_detect_loss(): when an ACK acknowledges all packets marked lost before receiving this ACK, but has not yet to discover new ones by tcp_rack_detect_loss(). The fix is to simply test the congestion state directly. Signed-off-by: Yuchung Cheng Reviewed-by: Neal Cardwell Reviewed-by: Priyaranjan Jha Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/tcp_recovery.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/ipv4/tcp_recovery.c b/net/ipv4/tcp_recovery.c index d3ea89020c69..3143664902e9 100644 --- a/net/ipv4/tcp_recovery.c +++ b/net/ipv4/tcp_recovery.c @@ -55,7 +55,8 @@ static void tcp_rack_detect_loss(struct sock *sk, u32 *reo_timeout) * to queuing or delayed ACKs. */ reo_wnd = 1000; - if ((tp->rack.reord || !tp->lost_out) && min_rtt != ~0U) { + if ((tp->rack.reord || inet_csk(sk)->icsk_ca_state < TCP_CA_Recovery) && + min_rtt != ~0U) { reo_wnd = max((min_rtt >> 2) * tp->rack.reo_wnd_steps, reo_wnd); reo_wnd = min(reo_wnd, tp->srtt_us >> 3); } -- 2.30.2