[IPV6]: Cleanups for net/ipv6/addrconf.c (kzalloc, early exit) v2

Here are some possible (and trivial) cleanups.
- use kzalloc() where possible
- invert allocation failure test like
  if (object) {
        /* Rest of function here */
  }
  to

  if (object == NULL)
        return NULL;

  /* Rest of function here */
Signed-off-by: NIngo Oeser <ioe-lkml@rameria.de>
Acked-by: NYOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv6/addrconf.c

@@ -341,10 +341,10 @@ static struct inet6_dev * ipv6_add_dev(struct net_device *dev)
 	if (dev->mtu < IPV6_MIN_MTU)
 		return NULL;
 
-	ndev = kmalloc(sizeof(struct inet6_dev), GFP_KERNEL);
+ 	ndev = kzalloc(sizeof(struct inet6_dev), GFP_KERNEL);
 
-	if (ndev) {
-		memset(ndev, 0, sizeof(struct inet6_dev));
+ 	if (ndev == NULL)
+ 		return NULL;
 
 	rwlock_init(&ndev->lock);
 	ndev->dev = dev;
@@ -418,7 +418,6 @@ static struct inet6_dev * ipv6_add_dev(struct net_device *dev)
 			      NULL);
 	addrconf_sysctl_register(ndev, &ndev->cnf);
 #endif
-	}
 	return ndev;
 }
 
@@ -536,7 +535,7 @@ ipv6_add_addr(struct inet6_dev *idev, const struct in6_addr *addr, int pfxlen,
 		goto out;
 	}
 
-	ifa = kmalloc(sizeof(struct inet6_ifaddr), GFP_ATOMIC);
+	ifa = kzalloc(sizeof(struct inet6_ifaddr), GFP_ATOMIC);
 
 	if (ifa == NULL) {
 		ADBG(("ipv6_add_addr: malloc failed\n"));
@@ -550,7 +549,6 @@ ipv6_add_addr(struct inet6_dev *idev, const struct in6_addr *addr, int pfxlen,
 		goto out;
 	}
 
-	memset(ifa, 0, sizeof(struct inet6_ifaddr));
 	ipv6_addr_copy(&ifa->addr, addr);
 
 	spin_lock_init(&ifa->lock);
@@ -2669,11 +2667,10 @@ static int if6_seq_open(struct inode *inode, struct file *file)
 {
 	struct seq_file *seq;
 	int rc = -ENOMEM;
-	struct if6_iter_state *s = kmalloc(sizeof(*s), GFP_KERNEL);
+	struct if6_iter_state *s = kzalloc(sizeof(*s), GFP_KERNEL);
 
 	if (!s)
 		goto out;
-	memset(s, 0, sizeof(*s));
 
 	rc = seq_open(file, &if6_seq_ops);
 	if (rc)