ipv4: coding style: comparison for equality with NULL

The ipv4 code uses a mixture of coding styles. In some instances check
for NULL pointer is done as x == NULL and sometimes as !x. !x is
preferred according to checkpatch and this patch makes the code
consistent by adopting the latter form.

No changes detected by objdiff.

Signed-off-by: Ian Morris <ipm@chirality.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 8259e77..561d67b 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -182,7 +182,7 @@
 		struct sk_buff *skb2;
 
 		skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev));
-		if (skb2 == NULL) {
+		if (!skb2) {
 			kfree_skb(skb);
 			return -ENOMEM;
 		}
@@ -381,7 +381,7 @@
 
 	/* Make sure we can route this packet. */
 	rt = (struct rtable *)__sk_dst_check(sk, 0);
-	if (rt == NULL) {
+	if (!rt) {
 		__be32 daddr;
 
 		/* Use correct destination address if we have options. */
@@ -790,12 +790,13 @@
 	 * device, so create one single skb packet containing complete
 	 * udp datagram
 	 */
-	if ((skb = skb_peek_tail(queue)) == NULL) {
+	skb = skb_peek_tail(queue);
+	if (!skb) {
 		skb = sock_alloc_send_skb(sk,
 			hh_len + fragheaderlen + transhdrlen + 20,
 			(flags & MSG_DONTWAIT), &err);
 
-		if (skb == NULL)
+		if (!skb)
 			return err;
 
 		/* reserve space for Hardware header */
@@ -961,10 +962,10 @@
 					skb = sock_wmalloc(sk,
 							   alloclen + hh_len + 15, 1,
 							   sk->sk_allocation);
-				if (unlikely(skb == NULL))
+				if (unlikely(!skb))
 					err = -ENOBUFS;
 			}
-			if (skb == NULL)
+			if (!skb)
 				goto error;
 
 			/*
@@ -1088,10 +1089,10 @@
 	 */
 	opt = ipc->opt;
 	if (opt) {
-		if (cork->opt == NULL) {
+		if (!cork->opt) {
 			cork->opt = kmalloc(sizeof(struct ip_options) + 40,
 					    sk->sk_allocation);
-			if (unlikely(cork->opt == NULL))
+			if (unlikely(!cork->opt))
 				return -ENOBUFS;
 		}
 		memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen);
@@ -1198,7 +1199,8 @@
 		return -EMSGSIZE;
 	}
 
-	if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)
+	skb = skb_peek_tail(&sk->sk_write_queue);
+	if (!skb)
 		return -EINVAL;
 
 	cork->length += size;
@@ -1329,7 +1331,8 @@
 	__be16 df = 0;
 	__u8 ttl;
 
-	if ((skb = __skb_dequeue(queue)) == NULL)
+	skb = __skb_dequeue(queue);
+	if (!skb)
 		goto out;
 	tail_skb = &(skb_shinfo(skb)->frag_list);