[NETFILTER]: nf_conntrack: simplify l4 protocol array allocation

The retrying after an allocation failure is not necessary anymore
since we're holding the mutex the entire time, for the same
reason the double allocation race can't happen anymore.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/netfilter/nf_conntrack_proto.c

@@ -281,47 +281,34 @@ int nf_conntrack_l4proto_register(struct nf_conntrack_l4proto *l4proto)
 		return -EBUSY;
 
 	mutex_lock(&nf_ct_proto_mutex);
-retry:
-	if (nf_ct_protos[l4proto->l3proto]) {
-		if (nf_ct_protos[l4proto->l3proto][l4proto->l4proto]
-				!= &nf_conntrack_l4proto_generic) {
-			ret = -EBUSY;
-			goto out_unlock;
-		}
-	} else {
+	if (!nf_ct_protos[l4proto->l3proto]) {
 		/* l3proto may be loaded latter. */
 		struct nf_conntrack_l4proto **proto_array;
 		int i;
 
-		proto_array = (struct nf_conntrack_l4proto **)
-				kmalloc(MAX_NF_CT_PROTO *
+		proto_array = kmalloc(MAX_NF_CT_PROTO *
 				      sizeof(struct nf_conntrack_l4proto *),
 				      GFP_KERNEL);
 		if (proto_array == NULL) {
 			ret = -ENOMEM;
 			goto out_unlock;
 		}
+
 		for (i = 0; i < MAX_NF_CT_PROTO; i++)
 			proto_array[i] = &nf_conntrack_l4proto_generic;
-
-		if (nf_ct_protos[l4proto->l3proto])
-			/* bad timing, but no problem */
-			kfree(proto_array);
-		else
 		nf_ct_protos[l4proto->l3proto] = proto_array;
-
-		/*
-		 * Just once because array is never freed until unloading
-		 * nf_conntrack.ko
-		 */
-		goto retry;
+	} else if (nf_ct_protos[l4proto->l3proto][l4proto->l4proto] !=
+					&nf_conntrack_l4proto_generic) {
+		ret = -EBUSY;
+		goto out_unlock;
 	}
 
 	ret = nf_ct_l4proto_register_sysctl(l4proto);
 	if (ret < 0)
 		goto out_unlock;
 
-	rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto], l4proto);
+	rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
+			   l4proto);
 
 out_unlock:
 	mutex_unlock(&nf_ct_proto_mutex);