ipv4: Use IS_ERR_OR_NULL().

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 79c8dbe..cf6158f 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -971,7 +971,7 @@
 				  sizeof(struct udphdr), &ipc, &rt,
 				  msg->msg_flags);
 		err = PTR_ERR(skb);
-		if (skb && !IS_ERR(skb))
+		if (!IS_ERR_OR_NULL(skb))
 			err = udp_send_skb(skb, fl4);
 		goto out;
 	}