tcp: fix SO_RCVLOWAT and RCVBUF autotuning
Applications might use SO_RCVLOWAT on TCP socket hoping to receive
one [E]POLLIN event only when a given amount of bytes are ready in socket
receive queue.
Problem is that receive autotuning is not aware of this constraint,
meaning sk_rcvbuf might be too small to allow all bytes to be stored.
Add a new (struct proto_ops)->set_rcvlowat method so that a protocol
can override the default setsockopt(SO_RCVLOWAT) behavior.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/sock.c b/net/core/sock.c
index 6444525..b2c3db1 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -905,7 +905,10 @@ int sock_setsockopt(struct socket *sock, int level, int optname,
case SO_RCVLOWAT:
if (val < 0)
val = INT_MAX;
- sk->sk_rcvlowat = val ? : 1;
+ if (sock->ops->set_rcvlowat)
+ ret = sock->ops->set_rcvlowat(sk, val);
+ else
+ sk->sk_rcvlowat = val ? : 1;
break;
case SO_RCVTIMEO: