[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>
diff --git a/net/llc/af_llc.c b/net/llc/af_llc.c
index c3f0b07..b6d3df5 100644
--- a/net/llc/af_llc.c
+++ b/net/llc/af_llc.c
@@ -566,10 +566,9 @@
 		/*
 		 * POSIX 1003.1g mandates this order.
 		 */
-		if (sk->sk_err) {
-			rc = sock_error(sk);
+		rc = sock_error(sk);
+		if (rc)
 			break;
-		}
 		rc = 0;
 		if (sk->sk_shutdown & RCV_SHUTDOWN)
 			break;