netlink: use blocking notifier

netlink_chain is called in ->release(), which is apparently
a process context, so we don't have to use an atomic notifier
here.
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/netlink/af_netlink.c

@@ -113,7 +113,7 @@ static atomic_t nl_table_users = ATOMIC_INIT(0);
 
 #define nl_deref_protected(X) rcu_dereference_protected(X, lockdep_is_held(&nl_table_lock));
 
-static ATOMIC_NOTIFIER_HEAD(netlink_chain);
+static BLOCKING_NOTIFIER_HEAD(netlink_chain);
 
 static DEFINE_SPINLOCK(netlink_tap_lock);
 static struct list_head netlink_tap_all __read_mostly;
@@ -711,7 +711,7 @@ static int netlink_release(struct socket *sock)
 						.protocol = sk->sk_protocol,
 						.portid = nlk->portid,
 					  };
-		atomic_notifier_call_chain(&netlink_chain,
+		blocking_notifier_call_chain(&netlink_chain,
 				NETLINK_URELEASE, &n);
 	}
 
@@ -2504,13 +2504,13 @@ static const struct file_operations netlink_seq_fops = {
 
 int netlink_register_notifier(struct notifier_block *nb)
 {
-	return atomic_notifier_chain_register(&netlink_chain, nb);
+	return blocking_notifier_chain_register(&netlink_chain, nb);
 }
 EXPORT_SYMBOL(netlink_register_notifier);
 
 int netlink_unregister_notifier(struct notifier_block *nb)
 {
-	return atomic_notifier_chain_unregister(&netlink_chain, nb);
+	return blocking_notifier_chain_unregister(&netlink_chain, nb);
 }
 EXPORT_SYMBOL(netlink_unregister_notifier);