[IPV6]: make inet6_register_protosw to return an error code

This patch makes the inet6_register_protosw to return an error code.
The different protocols can be aware the registration was successful or
not and can pass the error to the initial caller, af_inet6.
Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/protocol.h

@@ -102,7 +102,7 @@ extern void	inet_unregister_protosw(struct inet_protosw *p);
 #if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
 extern int	inet6_add_protocol(struct inet6_protocol *prot, unsigned char num);
 extern int	inet6_del_protocol(struct inet6_protocol *prot, unsigned char num);
-extern void	inet6_register_protosw(struct inet_protosw *p);
+extern int	inet6_register_protosw(struct inet_protosw *p);
 extern void	inet6_unregister_protosw(struct inet_protosw *p);
 #endif
 

net/ipv6/af_inet6.c

@@ -565,21 +565,23 @@ static struct inet_protosw rawv6_protosw = {
 	.flags		= INET_PROTOSW_REUSE,
 };
 
-void
-inet6_register_protosw(struct inet_protosw *p)
+int inet6_register_protosw(struct inet_protosw *p)
 {
 	struct list_head *lh;
 	struct inet_protosw *answer;
-	int protocol = p->protocol;
 	struct list_head *last_perm;
+	int protocol = p->protocol;
+	int ret;
 
 	spin_lock_bh(&inetsw6_lock);
 
+	ret = -EINVAL;
 	if (p->type >= SOCK_MAX)
 		goto out_illegal;
 
 	/* If we are trying to override a permanent protocol, bail. */
 	answer = NULL;
+	ret = -EPERM;
 	last_perm = &inetsw6[p->type];
 	list_for_each(lh, &inetsw6[p->type]) {
 		answer = list_entry(lh, struct inet_protosw, list);
@@ -603,9 +605,10 @@ inet6_register_protosw(struct inet_protosw *p)
 	 * system automatically returns to the old behavior.
 	 */
 	list_add_rcu(&p->list, last_perm);
+	ret = 0;
 out:
 	spin_unlock_bh(&inetsw6_lock);
-	return;
+	return ret;
 
 out_permanent:
 	printk(KERN_ERR "Attempt to override permanent protocol %d.\n",