diff options
| author | Enke Chen <enchen@paloaltonetworks.com> | 2021-01-22 11:13:06 -0800 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2021-01-23 19:32:51 -0800 |
| commit | 344db93ae3ee69fc137bd6ed89a8ff1bf5b0db08 (patch) | |
| tree | 9550bba9e51fe81198e0e36c626a4d762e0487f5 | |
| parent | 3a30537cee233fb7da302491b28c832247d89bbe (diff) | |
tcp: make TCP_USER_TIMEOUT accurate for zero window probes
The TCP_USER_TIMEOUT is checked by the 0-window probe timer. As the
timer has backoff with a max interval of about two minutes, the
actual timeout for TCP_USER_TIMEOUT can be off by up to two minutes.
In this patch the TCP_USER_TIMEOUT is made more accurate by taking it
into account when computing the timer value for the 0-window probes.
This patch is similar to and builds on top of the one that made
TCP_USER_TIMEOUT accurate for RTOs in commit b701a99e431d ("tcp: Add
tcp_clamp_rto_to_user_timeout() helper to improve accuracy").
Fixes: 9721e709fa68 ("tcp: simplify window probe aborting on USER_TIMEOUT")
Signed-off-by: Enke Chen <enchen@paloaltonetworks.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20210122191306.GA99540@localhost.localdomain
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rw-r--r-- | include/net/tcp.h | 1 | ||||
| -rw-r--r-- | net/ipv4/tcp_input.c | 4 | ||||
| -rw-r--r-- | net/ipv4/tcp_output.c | 2 | ||||
| -rw-r--r-- | net/ipv4/tcp_timer.c | 18 |
4 files changed, 23 insertions, 2 deletions
diff --git a/include/net/tcp.h b/include/net/tcp.h index 78d13c88720f..ca7e2c6cc663 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -630,6 +630,7 @@ static inline void tcp_clear_xmit_timers(struct sock *sk) unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu); unsigned int tcp_current_mss(struct sock *sk); +u32 tcp_clamp_probe0_to_user_timeout(const struct sock *sk, u32 when); /* Bound MSS / TSO packet size with the half of the window */ static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index a7dfca0a38cd..55c6fd6b5d13 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3392,8 +3392,8 @@ static void tcp_ack_probe(struct sock *sk) } else { unsigned long when = tcp_probe0_when(sk, TCP_RTO_MAX); - tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0, - when, TCP_RTO_MAX); + when = tcp_clamp_probe0_to_user_timeout(sk, when); + tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0, when, TCP_RTO_MAX); } } diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index ab458697881e..8478cf749821 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -4099,6 +4099,8 @@ void tcp_send_probe0(struct sock *sk) */ timeout = TCP_RESOURCE_PROBE_INTERVAL; } + + timeout = tcp_clamp_probe0_to_user_timeout(sk, timeout); tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0, timeout, TCP_RTO_MAX); } diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c index faa92948441b..4ef08079ccfa 100644 --- a/net/ipv4/tcp_timer.c +++ b/net/ipv4/tcp_timer.c @@ -40,6 +40,24 @@ static u32 tcp_clamp_rto_to_user_timeout(const struct sock *sk) return min_t(u32, icsk->icsk_rto, msecs_to_jiffies(remaining)); } +u32 tcp_clamp_probe0_to_user_timeout(const struct sock *sk, u32 when) +{ + struct inet_connection_sock *icsk = inet_csk(sk); + u32 remaining; + s32 elapsed; + + if (!icsk->icsk_user_timeout || !icsk->icsk_probes_tstamp) + return when; + + elapsed = tcp_jiffies32 - icsk->icsk_probes_tstamp; + if (unlikely(elapsed < 0)) + elapsed = 0; + remaining = msecs_to_jiffies(icsk->icsk_user_timeout) - elapsed; + remaining = max_t(u32, remaining, TCP_TIMEOUT_MIN); + + return min_t(u32, remaining, when); +} + /** * tcp_write_err() - close socket and save error info * @sk: The socket the error has appeared on. |