From 58ec3b4db9eb5a28e3aec5f407a54e28f7039c19 Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Tue, 7 Oct 2008 15:50:03 -0700 Subject: net: Fix netdev_run_todo dead-lock Benjamin Thery tracked down a bug that explains many instances of the error unregister_netdevice: waiting for %s to become free. Usage count = %d It turns out that netdev_run_todo can dead-lock with itself if a second instance of it is run in a thread that will then free a reference to the device waited on by the first instance. The problem is really quite silly. We were trying to create parallelism where none was required. As netdev_run_todo always follows a RTNL section, and that todo tasks can only be added with the RTNL held, by definition you should only need to wait for the very ones that you've added and be done with it. There is no need for a second mutex or spinlock. This is exactly what the following patch does. Signed-off-by: Herbert Xu Signed-off-by: David S. Miller --- net/core/rtnetlink.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/core/rtnetlink.c') diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index 71edb8b36341..d6381c2a4693 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -73,7 +73,7 @@ void __rtnl_unlock(void) void rtnl_unlock(void) { - mutex_unlock(&rtnl_mutex); + /* This fellow will unlock it for us. */ netdev_run_todo(); } -- cgit v1.2.3