[NET]: Avoid atomic xchg() for non-error case

It also looks like there were 2 places where the test on sk_err was
missing from the event wait logic (in sk_stream_wait_connect and
sk_stream_wait_memory), while the rest of the sock_error() users look
to be doing the right thing.  This version of the patch fixes those,
and cleans up a few places that were testing ->sk_err directly.

Signed-off-by: Benjamin LaHaise <benjamin.c.lahaise@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 1 deletions

diff --git a/include/net/sock.h b/include/net/sock.h
index 982b4ec..0fbae85 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1166,7 +1166,10 @@ static inline int sock_queue_err_skb(struct sock *sk, struct sk_buff *skb)
  
 static inline int sock_error(struct sock *sk)
 {
-	int err = xchg(&sk->sk_err, 0);
+	int err;
+	if (likely(!sk->sk_err))
+		return 0;
+	err = xchg(&sk->sk_err, 0);
 	return -err;
 }