diff options
| author | Eric Dumazet <edumazet@google.com> | 2017-04-18 19:45:52 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-04-20 22:42:11 +0300 |
| commit | 0f9fa831aecfc297b7b45d4f046759bcefcf87f0 (patch) | |
| tree | 24e08556cbd89b183cfb02743e268f61346e9997 /net/ipv4/tcp_input.c | |
| parent | 3d4762639dd36a5f0f433f0c9d82e9743dc21a33 (diff) | |
| download | linux-0f9fa831aecfc297b7b45d4f046759bcefcf87f0.tar.xz | |
tcp: remove poll() flakes with FastOpen
When using TCP FastOpen for an active session, we send one wakeup event
from tcp_finish_connect(), right before the data eventually contained in
the received SYNACK is queued to sk->sk_receive_queue.
This means that depending on machine load or luck, poll() users
might receive POLLOUT events instead of POLLIN|POLLOUT
To fix this, we need to move the call to sk->sk_state_change()
after the (optional) call to tcp_rcv_fastopen_synack()
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_input.c')
| -rw-r--r-- | net/ipv4/tcp_input.c | 16 |
1 files changed, 9 insertions, 7 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 37e2aa925f62..341f021f02a2 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -5580,10 +5580,6 @@ void tcp_finish_connect(struct sock *sk, struct sk_buff *skb) else tp->pred_flags = 0; - if (!sock_flag(sk, SOCK_DEAD)) { - sk->sk_state_change(sk); - sk_wake_async(sk, SOCK_WAKE_IO, POLL_OUT); - } } static bool tcp_rcv_fastopen_synack(struct sock *sk, struct sk_buff *synack, @@ -5652,6 +5648,7 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb, struct tcp_sock *tp = tcp_sk(sk); struct tcp_fastopen_cookie foc = { .len = -1 }; int saved_clamp = tp->rx_opt.mss_clamp; + bool fastopen_fail; tcp_parse_options(skb, &tp->rx_opt, 0, &foc); if (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr) @@ -5755,10 +5752,15 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb, tcp_finish_connect(sk, skb); - if ((tp->syn_fastopen || tp->syn_data) && - tcp_rcv_fastopen_synack(sk, skb, &foc)) - return -1; + fastopen_fail = (tp->syn_fastopen || tp->syn_data) && + tcp_rcv_fastopen_synack(sk, skb, &foc); + if (!sock_flag(sk, SOCK_DEAD)) { + sk->sk_state_change(sk); + sk_wake_async(sk, SOCK_WAKE_IO, POLL_OUT); + } + if (fastopen_fail) + return -1; if (sk->sk_write_pending || icsk->icsk_accept_queue.rskq_defer_accept || icsk->icsk_ack.pingpong) { |