diff options
| author | Nikolay Aleksandrov <nikolay@redhat.com> | 2013-09-19 15:02:36 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2013-09-19 14:15:53 -0400 |
| commit | c71380ff0b199f1e8be5ca46dd91262f7fbe4cb4 (patch) | |
| tree | 4d753b6aa3cb50f68f15e85b02cc7f17a443c802 /drivers/net/netconsole.c | |
| parent | d0fe8c888b1fd1a2f84b9962cabcb98a70988aec (diff) | |
| download | lwn-c71380ff0b199f1e8be5ca46dd91262f7fbe4cb4.tar.gz lwn-c71380ff0b199f1e8be5ca46dd91262f7fbe4cb4.zip | |
netconsole: fix a deadlock with rtnl and netconsole's mutex
This bug was introduced by commit
7a163bfb7ce50895bbe67300ea610d31b9c09230 ("netconsole: avoid a crash with
multiple sysfs writers"). In store_enabled() we have the following
sequence: acquire nt->mutex then rtnl, but in the netconsole netdev
notifier we have rtnl then nt->mutex effectively leading to a deadlock.
The NULL pointer dereference that the above commit tries to fix is
actually due to another bug in netpoll_cleanup(). This is fixed by dropping
the mutex from the netdev notifier as it's already protected by rtnl.
Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/netconsole.c')
| -rw-r--r-- | drivers/net/netconsole.c | 5 |
1 files changed, 1 insertions, 4 deletions
diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c index dcb21347c670..adeee615dd19 100644 --- a/drivers/net/netconsole.c +++ b/drivers/net/netconsole.c @@ -684,15 +684,12 @@ restart: case NETDEV_RELEASE: case NETDEV_JOIN: case NETDEV_UNREGISTER: - /* - * rtnl_lock already held + /* rtnl_lock already held * we might sleep in __netpoll_cleanup() */ spin_unlock_irqrestore(&target_list_lock, flags); - mutex_lock(&nt->mutex); __netpoll_cleanup(&nt->np); - mutex_unlock(&nt->mutex); spin_lock_irqsave(&target_list_lock, flags); dev_put(nt->np.dev); |