caif: Fix BUG() with network namespaces
authorDavid Woodhouse <dwmw2@infradead.org>
Mon, 24 Oct 2011 21:25:21 +0000 (21:25 +0000)
committerDavid S. Miller <davem@davemloft.net>
Tue, 25 Oct 2011 23:22:23 +0000 (19:22 -0400)
commit08613e4626c06ca408fc55071f6aedee36986a87
tree4251c4fa37ed1571a61505a70fed4dffdaaece82
parent59fdaca9a4497ada47328d7b4b406b98a6f1c1a6
caif: Fix BUG() with network namespaces

The caif code will register its own pernet_operations, and then register
a netdevice_notifier. Each time the netdevice_notifier is triggered,
it'll do some stuff... including a lookup of its own pernet stuff with
net_generic().

If the net_generic() call ever returns NULL, the caif code will BUG().
That doesn't seem *so* unreasonable, I suppose â€” it does seem like it
should never happen.

However, it *does* happen. When we clone a network namespace,
setup_net() runs through all the pernet_operations one at a time. It
gets to loopback before it gets to caif. And loopback_net_init()
registers a netdevice... while caif hasn't been initialised. So the caif
netdevice notifier triggers, and immediately goes BUG().

We could imagine a complex and overengineered solution to this generic
class of problems, but this patch takes the simple approach. It just
makes caif_device_notify() *not* go looking for its pernet data
structures if the device it's being notified about isn't a caif device
in the first place.

Cc: stable@kernel.org
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Acked-by: Sjur Brændeland <sjur.brandeland@stericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/caif/caif_dev.c