tcp: make TCP_USER_TIMEOUT accurate for zero window probes
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 commitb701a99e43
("tcp: Add tcp_clamp_rto_to_user_timeout() helper to improve accuracy"). Fixes:9721e709fa
("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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -619,6 +619,7 @@ static inline void tcp_clear_xmit_timers(struct sock *sk)
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unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
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unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
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unsigned int tcp_current_mss(struct sock *sk);
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unsigned int tcp_current_mss(struct sock *sk);
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u32 tcp_clamp_probe0_to_user_timeout(const struct sock *sk, u32 when);
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/* Bound MSS / TSO packet size with the half of the window */
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/* Bound MSS / TSO packet size with the half of the window */
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static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
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static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
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@ -3295,6 +3295,7 @@ static void tcp_ack_probe(struct sock *sk)
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} else {
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} else {
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unsigned long when = tcp_probe0_when(sk, TCP_RTO_MAX);
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unsigned long when = tcp_probe0_when(sk, TCP_RTO_MAX);
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when = tcp_clamp_probe0_to_user_timeout(sk, when);
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tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
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tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
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when, TCP_RTO_MAX, NULL);
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when, TCP_RTO_MAX, NULL);
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}
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}
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@ -3850,6 +3850,8 @@ void tcp_send_probe0(struct sock *sk)
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*/
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*/
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timeout = TCP_RESOURCE_PROBE_INTERVAL;
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timeout = TCP_RESOURCE_PROBE_INTERVAL;
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}
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}
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timeout = tcp_clamp_probe0_to_user_timeout(sk, timeout);
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tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0, timeout, TCP_RTO_MAX, NULL);
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tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0, timeout, TCP_RTO_MAX, NULL);
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}
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}
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@ -40,6 +40,24 @@ static u32 tcp_clamp_rto_to_user_timeout(const struct sock *sk)
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return min_t(u32, icsk->icsk_rto, msecs_to_jiffies(remaining));
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return min_t(u32, icsk->icsk_rto, msecs_to_jiffies(remaining));
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}
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}
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u32 tcp_clamp_probe0_to_user_timeout(const struct sock *sk, u32 when)
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{
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struct inet_connection_sock *icsk = inet_csk(sk);
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u32 remaining;
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s32 elapsed;
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if (!icsk->icsk_user_timeout || !icsk->icsk_probes_tstamp)
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return when;
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elapsed = tcp_jiffies32 - icsk->icsk_probes_tstamp;
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if (unlikely(elapsed < 0))
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elapsed = 0;
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remaining = msecs_to_jiffies(icsk->icsk_user_timeout) - elapsed;
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remaining = max_t(u32, remaining, TCP_TIMEOUT_MIN);
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return min_t(u32, remaining, when);
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}
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/**
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/**
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* tcp_write_err() - close socket and save error info
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* tcp_write_err() - close socket and save error info
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* @sk: The socket the error has appeared on.
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* @sk: The socket the error has appeared on.
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