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authorYuchung Cheng <ycheng@google.com>2019-01-16 15:05:33 -0800
committerDavid S. Miller <davem@davemloft.net>2019-01-17 15:12:26 -0800
commit9721e709fa68ef9b860c322b474cfbd1f8285b0f (patch)
treebfa0865947efad2293f0d210dbe7451e342eb2da /net/ipv4/tcp_timer.c
parenttcp: create a helper to model exponential backoff (diff)
downloadlinux-dev-9721e709fa68ef9b860c322b474cfbd1f8285b0f.tar.xz
linux-dev-9721e709fa68ef9b860c322b474cfbd1f8285b0f.zip
tcp: simplify window probe aborting on USER_TIMEOUT
Previously we use the next unsent skb's timestamp to determine when to abort a socket stalling on window probes. This no longer works as skb timestamp reflects the last instead of the first transmission. Instead we can estimate how long the socket has been stalling with the probe count and the exponential backoff behavior. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Neal Cardwell <ncardwell@google.com> Reviewed-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_timer.c')
-rw-r--r--net/ipv4/tcp_timer.c14
1 files changed, 7 insertions, 7 deletions
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index bcc2f5783e57..c36089aa3515 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -333,7 +333,6 @@ static void tcp_probe_timer(struct sock *sk)
struct sk_buff *skb = tcp_send_head(sk);
struct tcp_sock *tp = tcp_sk(sk);
int max_probes;
- u32 start_ts;
if (tp->packets_out || !skb) {
icsk->icsk_probes_out = 0;
@@ -348,12 +347,13 @@ static void tcp_probe_timer(struct sock *sk)
* corresponding system limit. We also implement similar policy when
* we use RTO to probe window in tcp_retransmit_timer().
*/
- start_ts = tcp_skb_timestamp(skb);
- if (!start_ts)
- skb->skb_mstamp_ns = tp->tcp_clock_cache;
- else if (icsk->icsk_user_timeout &&
- (s32)(tcp_time_stamp(tp) - start_ts) > icsk->icsk_user_timeout)
- goto abort;
+ if (icsk->icsk_user_timeout) {
+ u32 elapsed = tcp_model_timeout(sk, icsk->icsk_probes_out,
+ tcp_probe0_base(sk));
+
+ if (elapsed >= icsk->icsk_user_timeout)
+ goto abort;
+ }
max_probes = sock_net(sk)->ipv4.sysctl_tcp_retries2;
if (sock_flag(sk, SOCK_DEAD)) {