tcp: add memory barriers to write space paths
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>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index a7ef679..3a4d9b34 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4845,6 +4845,8 @@
{
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);