[NET]: Fix race condition in sk_wait_event().

It is broken, the condition is checked out of socket lock. It is
wonderful the bug survived for so long time.

[ This fixes bugzilla #6233:
  race condition in tcp_sendmsg when connection became established ]
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/net/sock.h

@@ -478,9 +478,9 @@ static inline void sk_add_backlog(struct sock *sk, struct sk_buff *skb)
 	rc = __condition;					\
 	if (!rc) {						\
 		*(__timeo) = schedule_timeout(*(__timeo));	\
-		rc = __condition;				\
 	}							\
 	lock_sock(__sk);					\
+	rc = __condition;					\
 	rc;							\
 })