udp6: shuffle up->pending AF_INET bits

Corked AF_INET for ipv6 socket doesn't appear to be the hottest case,
so move it out of the common path under up->pending check to remove
overhead.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/ipv6/udp.c

@@ -1363,9 +1363,6 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 		}
 	}
 
-	if (up->pending == AF_INET)
-		return udp_sendmsg(sk, msg, len);
-
 	/* Rough check on arithmetic overflow,
 	   better check is made in ip6_append_data().
 	   */
@@ -1374,6 +1371,8 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 
 	getfrag  =  is_udplite ?  udplite_getfrag : ip_generic_getfrag;
 	if (up->pending) {
+		if (up->pending == AF_INET)
+			return udp_sendmsg(sk, msg, len);
 		/*
 		 * There are pending frames.
 		 * The socket lock must be held while it's corked.