From: Eric W. Biederman <ebiederm@xmission.com>
Date: Thu, 3 Dec 2009 02:29:06 +0000 (+0000)
Subject: netns: Add an explicit rcu_barrier to unregister_pernet_{device|subsys}
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=3a765edadb28;p=linux.git

netns: Add an explicit rcu_barrier to unregister_pernet_{device|subsys}

This allows namespace exit methods to batch work that comes requires an
rcu barrier using call_rcu without having to treat the
unregister_pernet_operations cases specially.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 4026a4cff93cd..bd8c4712ea247 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -413,8 +413,11 @@ again:
 		}
 	}
 	error = __register_pernet_operations(list, ops);
-	if (error && ops->id)
-		ida_remove(&net_generic_ids, *ops->id);
+	if (error) {
+		rcu_barrier();
+		if (ops->id)
+			ida_remove(&net_generic_ids, *ops->id);
+	}
 
 	return error;
 }
@@ -423,6 +426,7 @@ static void unregister_pernet_operations(struct pernet_operations *ops)
 {
 	
 	__unregister_pernet_operations(ops);
+	rcu_barrier();
 	if (ops->id)
 		ida_remove(&net_generic_ids, *ops->id);
 }