| Message ID | 20150420200507.21414203F@prod-mail-relay06.akamai.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
From: Jason Baron <jbaron@akamai.com> Date: Mon, 20 Apr 2015 20:05:07 +0000 (GMT) > Ensure that we either see that the buffer has write space > in tcp_poll() or that we perform a wakeup from the input > side. Did not run into any actual problem here, but thought > that we should make things explicit. > > Signed-off-by: Jason Baron <jbaron@akamai.com> This looks fine, applied, thanks. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 094a682..726341e 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -520,8 +520,10 @@ unsigned int tcp_poll(struct file *file, struct socket *sock, poll_table *wait) /* Race breaker. If space is freed after * wspace test but before the flags are set, - * IO signal will be lost. + * IO signal will be lost. Memory barrier + * pairs with the input side. */ + smp_mb__after_atomic(); if (sk_stream_is_writeable(sk)) mask |= POLLOUT | POLLWRNORM; } diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 031cf72..63b3d4e9 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4847,6 +4847,8 @@ static void tcp_check_space(struct sock *sk) { if (sock_flag(sk, SOCK_QUEUE_SHRUNK)) { sock_reset_flag(sk, SOCK_QUEUE_SHRUNK); + /* pairs with tcp_poll() */ + smp_mb__after_atomic(); if (sk->sk_socket && test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) tcp_new_space(sk);
Ensure that we either see that the buffer has write space in tcp_poll() or that we perform a wakeup from the input side. Did not run into any actual problem here, but thought that we should make things explicit. Signed-off-by: Jason Baron <jbaron@akamai.com> --- net/ipv4/tcp.c | 4 +++- net/ipv4/tcp_input.c | 2 ++ 2 files changed, 5 insertions(+), 1 deletion(-)