summaryrefslogtreecommitdiffstats
path: root/net/ipv4/tcp_input.c
diff options
context:
space:
mode:
authorEnke Chen <enchen@paloaltonetworks.com>2021-01-15 23:30:58 +0100
committerJakub Kicinski <kuba@kernel.org>2021-01-19 04:59:17 +0100
commit9d9b1ee0b2d1c9e02b2338c4a4b0a062d2d3edac (patch)
tree2ea6293f10e4ca912540381678be42708f264e99 /net/ipv4/tcp_input.c
parentMerge branch 'ipv6-fixes-for-the-multicast-routes' (diff)
downloadlinux-9d9b1ee0b2d1c9e02b2338c4a4b0a062d2d3edac.tar.xz
linux-9d9b1ee0b2d1c9e02b2338c4a4b0a062d2d3edac.zip
tcp: fix TCP_USER_TIMEOUT with zero window
The TCP session does not terminate with TCP_USER_TIMEOUT when data remain untransmitted due to zero window. The number of unanswered zero-window probes (tcp_probes_out) is reset to zero with incoming acks irrespective of the window size, as described in tcp_probe_timer(): RFC 1122 4.2.2.17 requires the sender to stay open indefinitely as long as the receiver continues to respond probes. We support this by default and reset icsk_probes_out with incoming ACKs. This counter, however, is the wrong one to be used in calculating the duration that the window remains closed and data remain untransmitted. Thanks to Jonathan Maxwell <jmaxwell37@gmail.com> for diagnosing the actual issue. In this patch a new timestamp is introduced for the socket in order to track the elapsed time for the zero-window probes that have not been answered with any non-zero window ack. Fixes: 9721e709fa68 ("tcp: simplify window probe aborting on USER_TIMEOUT") Reported-by: William McCall <william.mccall@gmail.com> Co-developed-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Enke Chen <enchen@paloaltonetworks.com> Reviewed-by: Yuchung Cheng <ycheng@google.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://lore.kernel.org/r/20210115223058.GA39267@localhost.localdomain Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/ipv4/tcp_input.c')
-rw-r--r--net/ipv4/tcp_input.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index c7e16b0ed791..bafcab75f425 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3384,6 +3384,7 @@ static void tcp_ack_probe(struct sock *sk)
return;
if (!after(TCP_SKB_CB(head)->end_seq, tcp_wnd_end(tp))) {
icsk->icsk_backoff = 0;
+ icsk->icsk_probes_tstamp = 0;
inet_csk_clear_xmit_timer(sk, ICSK_TIME_PROBE0);
/* Socket must be waked up by subsequent tcp_data_snd_check().
* This function is not for random using!