]> git.proxmox.com Git - mirror_ubuntu-kernels.git/commit
tcp_bbr: apply PROBE_RTT cwnd cap even if acked==0
authorKevin Yang <yyd@google.com>
Wed, 22 Aug 2018 21:43:16 +0000 (17:43 -0400)
committerDavid S. Miller <davem@davemloft.net>
Thu, 23 Aug 2018 04:45:32 +0000 (21:45 -0700)
commit8e995bf14fdb7e33681d5c3312b602fa342b878a
treece51c37366551d55e5c7a3ae22f9849ec918c57a
parent5490b32dce6932ea7ee8e3b2f76db2957c92af6e
tcp_bbr: apply PROBE_RTT cwnd cap even if acked==0

This commit fixes a corner case where TCP BBR would enter PROBE_RTT
mode but not reduce its cwnd. If a TCP receiver ACKed less than one
full segment, the number of delivered/acked packets was 0, so that
bbr_set_cwnd() would short-circuit and exit early, without cutting
cwnd to the value we want for PROBE_RTT.

The fix is to instead make sure that even when 0 full packets are
ACKed, we do apply all the appropriate caps, including the cap that
applies in PROBE_RTT mode.

Fixes: 0f8782ea1497 ("tcp_bbr: add BBR congestion control")
Signed-off-by: Kevin Yang <yyd@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Reviewed-by: Yuchung Cheng <ycheng@google.com>
Reviewed-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/ipv4/tcp_bbr.c