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/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 69f9cf6..9ff311c 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -122,7 +122,7 @@
 	   and use initial timestamp retrieved from peer table.
 	 */
 	if (tcptw->tw_ts_recent_stamp &&
-	    (twp == NULL || (sysctl_tcp_tw_reuse &&
+	    (!twp || (sysctl_tcp_tw_reuse &&
 			     get_seconds() - tcptw->tw_ts_recent_stamp > 1))) {
 		tp->write_seq = tcptw->tw_snd_nxt + 65535 + 2;
 		if (tp->write_seq == 0)
@@ -494,7 +494,7 @@
 		/* Only in fast or simultaneous open. If a fast open socket is
 		 * is already accepted it is treated as a connected one below.
 		 */
-		if (fastopen && fastopen->sk == NULL)
+		if (fastopen && !fastopen->sk)
 			break;
 
 		if (!sock_owned_by_user(sk)) {
@@ -1390,7 +1390,7 @@
 		sk_mark_napi_id(sk, skb);
 		if (dst) {
 			if (inet_sk(sk)->rx_dst_ifindex != skb->skb_iif ||
-			    dst->ops->check(dst, 0) == NULL) {
+			    !dst->ops->check(dst, 0)) {
 				dst_release(dst);
 				sk->sk_rx_dst = NULL;
 			}