Defer input led work to workqueue

When the kbd changes its led state (e.g.  caps lock), this triggers
(led_trigger_event) the kbd-capsl trigger, which is by default used by the
vt::capsl LED, which triggers (led_trigger_event) the vt-capsl trigger.
These two nested led_trigger_event calls take a trig->leddev_list_lock
lock and thus lockdep complains.

Actually the user can make the vt::capsl LED use its own vt-capsl trigger
and thus build a loop.  This produces an immediate oops.

This changeset defers the second led_trigger_event call into a workqueue,
which avoids the nested locking altogether.  This does not prevent the
user from shooting himself in the foot by creating a vt::capsl <->
vt-capsl loop, but the only consequence is the workqueue threads eating
some CPU until the user breaks the loop, which is not too bad.

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

0 files changed, 0 insertions, 0 deletions