Commit 0f9fa831 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller

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: default avatarEric Dumazet <edumazet@google.com>
Acked-by: default avatarYuchung Cheng <ycheng@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 3d476263
...@@ -5580,10 +5580,6 @@ void tcp_finish_connect(struct sock *sk, struct sk_buff *skb) ...@@ -5580,10 +5580,6 @@ void tcp_finish_connect(struct sock *sk, struct sk_buff *skb)
else else
tp->pred_flags = 0; 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, 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, ...@@ -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_sock *tp = tcp_sk(sk);
struct tcp_fastopen_cookie foc = { .len = -1 }; struct tcp_fastopen_cookie foc = { .len = -1 };
int saved_clamp = tp->rx_opt.mss_clamp; int saved_clamp = tp->rx_opt.mss_clamp;
bool fastopen_fail;
tcp_parse_options(skb, &tp->rx_opt, 0, &foc); tcp_parse_options(skb, &tp->rx_opt, 0, &foc);
if (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr) 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, ...@@ -5755,10 +5752,15 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
tcp_finish_connect(sk, skb); tcp_finish_connect(sk, skb);
if ((tp->syn_fastopen || tp->syn_data) && fastopen_fail = (tp->syn_fastopen || tp->syn_data) &&
tcp_rcv_fastopen_synack(sk, skb, &foc)) tcp_rcv_fastopen_synack(sk, skb, &foc);
return -1;
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 || if (sk->sk_write_pending ||
icsk->icsk_accept_queue.rskq_defer_accept || icsk->icsk_accept_queue.rskq_defer_accept ||
icsk->icsk_ack.pingpong) { icsk->icsk_ack.pingpong) {
......
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