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/igmp.c b/net/ipv4/igmp.c
index ad09213..27d204b 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -692,7 +692,7 @@
 	hlen = LL_RESERVED_SPACE(dev);
 	tlen = dev->needed_tailroom;
 	skb = alloc_skb(IGMP_SIZE + hlen + tlen, GFP_ATOMIC);
-	if (skb == NULL) {
+	if (!skb) {
 		ip_rt_put(rt);
 		return -1;
 	}
@@ -981,7 +981,7 @@
 	int len = skb->len;
 	bool dropped = true;
 
-	if (in_dev == NULL)
+	if (!in_dev)
 		goto drop;
 
 	if (!pskb_may_pull(skb, sizeof(struct igmphdr)))
@@ -1888,7 +1888,7 @@
 	if (count >= sysctl_igmp_max_memberships)
 		goto done;
 	iml = sock_kmalloc(sk, sizeof(*iml), GFP_KERNEL);
-	if (iml == NULL)
+	if (!iml)
 		goto done;
 
 	memcpy(&iml->multi, imr, sizeof(*imr));
@@ -1909,7 +1909,7 @@
 	struct ip_sf_socklist *psf = rtnl_dereference(iml->sflist);
 	int err;
 
-	if (psf == NULL) {
+	if (!psf) {
 		/* any-source empty exclude case */
 		return ip_mc_del_src(in_dev, &iml->multi.imr_multiaddr.s_addr,
 			iml->sfmode, 0, NULL, 0);
@@ -2360,7 +2360,7 @@
 	struct ip_mc_socklist *iml;
 	struct net *net = sock_net(sk);
 
-	if (inet->mc_list == NULL)
+	if (!inet->mc_list)
 		return;
 
 	rtnl_lock();
@@ -2587,7 +2587,7 @@
 	for_each_netdev_rcu(net, state->dev) {
 		struct in_device *idev;
 		idev = __in_dev_get_rcu(state->dev);
-		if (unlikely(idev == NULL))
+		if (unlikely(!idev))
 			continue;
 		im = rcu_dereference(idev->mc_list);
 		if (likely(im != NULL)) {