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| author | Eric Dumazet <edumazet@google.com> | 2019-09-27 00:42:51 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2019-09-27 20:42:24 +0200 |
| commit | a41e8a88b06ee39fad4cb4a8ccf822563560a89c (patch) | |
| tree | 4cb7c743f2425c421a5604ae6232843a4055c949 | |
| parent | sk_buff: drop all skb extensions on free and skb scrubbing (diff) | |
| download | linux-a41e8a88b06ee39fad4cb4a8ccf822563560a89c.tar.xz linux-a41e8a88b06ee39fad4cb4a8ccf822563560a89c.zip | |
tcp: better handle TCP_USER_TIMEOUT in SYN_SENT state
Yuchung Cheng and Marek Majkowski independently reported a weird
behavior of TCP_USER_TIMEOUT option when used at connect() time.
When the TCP_USER_TIMEOUT is reached, tcp_write_timeout()
believes the flow should live, and the following condition
in tcp_clamp_rto_to_user_timeout() programs one jiffie timers :
remaining = icsk->icsk_user_timeout - elapsed;
if (remaining <= 0)
return 1; /* user timeout has passed; fire ASAP */
This silly situation ends when the max syn rtx count is reached.
This patch makes sure we honor both TCP_SYNCNT and TCP_USER_TIMEOUT,
avoiding these spurious SYN packets.
Fixes: b701a99e431d ("tcp: Add tcp_clamp_rto_to_user_timeout() helper to improve accuracy")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Yuchung Cheng <ycheng@google.com>
Reported-by: Marek Majkowski <marek@cloudflare.com>
Cc: Jon Maxwell <jmaxwell37@gmail.com>
Link: https://marc.info/?l=linux-netdev&m=156940118307949&w=2
Acked-by: Jon Maxwell <jmaxwell37@gmail.com>
Tested-by: Marek Majkowski <marek@cloudflare.com>
Signed-off-by: Marek Majkowski <marek@cloudflare.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/ipv4/tcp_timer.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c index dbd9d2d0ee63..40de2d2364a1 100644 --- a/net/ipv4/tcp_timer.c +++ b/net/ipv4/tcp_timer.c @@ -210,7 +210,7 @@ static int tcp_write_timeout(struct sock *sk) struct inet_connection_sock *icsk = inet_csk(sk); struct tcp_sock *tp = tcp_sk(sk); struct net *net = sock_net(sk); - bool expired, do_reset; + bool expired = false, do_reset; int retry_until; if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) { @@ -242,9 +242,10 @@ static int tcp_write_timeout(struct sock *sk) if (tcp_out_of_resources(sk, do_reset)) return 1; } + } + if (!expired) expired = retransmits_timed_out(sk, retry_until, icsk->icsk_user_timeout); - } tcp_fastopen_active_detect_blackhole(sk, expired); if (BPF_SOCK_OPS_TEST_FLAG(tp, BPF_SOCK_OPS_RTO_CB_FLAG)) |