devlink: Fix list access without lock while reading region
While finding the devlink device during region reading,
devlink device list is accessed and devlink device is
returned without holding a lock. This could lead to use-after-free
accesses.
While at it, add lockdep assert to ensure that all future callers hold
the lock when calling devlink_get_from_attrs().
Fixes: b41666a9e71d ("devlink: Add support for region snapshot read command") Signed-off-by: Parav Pandit <parav@mellanox.com> Acked-by: Jiri Pirko <jiri@mellanox.com> Signed-off-by: David S. Miller <davem@davemloft.net>