Hi, Greg:
Attach is the ported patch for the 5.4-stable tree.
Thanks. -- Enke
> From: <gregkh@xxxxxxxxxxxxxxxxxxx>
> Date: Tue, Feb 2, 2021 at 5:15 AM
> Subject: FAILED: patch "[PATCH] tcp: make TCP_USER_TIMEOUT accurate for
> zero window probes" failed to apply to 5.4-stable tree
> To: <enchen@xxxxxxxxxxxxxxxxxxxx>, <edumazet@xxxxxxxxxx>, <kuba@xxxxxxxxxx>,
> <ncardwell@xxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx>
>
>
>
> The patch below does not apply to the 5.4-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@xxxxxxxxxxxxxxx>.
>
> thanks,
>
> greg k-h
>
tcp: make TCP_USER_TIMEOUT accurate for zero window probes
From: Enke Chen <enchen@xxxxxxxxxxxxxxxxxxxx>
commit 344db93ae3ee69fc137bd6ed89a8ff1bf5b0db08 upstream.
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@xxxxxxxxxxxxxxxxxxxx>
Reviewed-by: Neal Cardwell <ncardwell@xxxxxxxxxx>
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20210122191306.GA99540@localhost.localdomain
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
---
include/net/tcp.h | 1 +
net/ipv4/tcp_input.c | 1 +
net/ipv4/tcp_output.c | 2 ++
net/ipv4/tcp_timer.c | 18 ++++++++++++++++++
4 files changed, 22 insertions(+)
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 377179283c46..424d4f137707 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -619,6 +619,7 @@ 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 7411a4313462..30c1b88ae4f7 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3294,6 +3294,7 @@ static void tcp_ack_probe(struct sock *sk)
} else {
unsigned long when = tcp_probe0_when(sk, TCP_RTO_MAX);
+ when = tcp_clamp_probe0_to_user_timeout(sk, when);
tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
when, TCP_RTO_MAX, NULL);
}
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 5da6ffce390c..d0774b4e934d 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -3850,6 +3850,8 @@ 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, NULL);
}
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 7fcd116fbd37..fa2ae96ecdc4 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.
--
2.29.2
