[IPV4] Fix EPROTONOSUPPORT error in inet_create

There is a coding error in inet_create that causes it to always return
ESOCKTNOSUPPORT.  It should return EPROTONOSUPPORT when there are
protocols registered for a given socket type but none of them match
the requested protocol.

This is based on a patch by Jayachandran C.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/af_inet.c

@@ -228,13 +228,14 @@ static int inet_create(struct socket *sock, int protocol)
 	unsigned char answer_flags;
 	char answer_no_check;
 	int try_loading_module = 0;
-	int err = -ESOCKTNOSUPPORT;
+	int err;
 
 	sock->state = SS_UNCONNECTED;
 
 	/* Look for the requested type/protocol pair. */
 	answer = NULL;
 lookup_protocol:
+	err = -ESOCKTNOSUPPORT;
 	rcu_read_lock();
 	list_for_each_rcu(p, &inetsw[sock->type]) {
 		answer = list_entry(p, struct inet_protosw, list);
@@ -252,6 +253,7 @@ lookup_protocol:
 			if (IPPROTO_IP == answer->protocol)
 				break;
 		}
+		err = -EPROTONOSUPPORT;
 		answer = NULL;
 	}
 
@@ -280,9 +282,6 @@ lookup_protocol:
 	err = -EPERM;
 	if (answer->capability > 0 && !capable(answer->capability))
 		goto out_rcu_unlock;
-	err = -EPROTONOSUPPORT;
-	if (!protocol)
-		goto out_rcu_unlock;
 
 	sock->ops = answer->ops;
 	answer_prot = answer->prot;