i915 notification is executed in a spinlock, thus it must not sleep;
i.e. we can't use kmalloc with GFP_KERNEL or such.
For making it working properly, move the notification handler in a
work, and handle it gracefully. We have already such a work, and it
was used just at the start. This can be re-used in a more generic
hotplug handling.
Also, the patch adds the proper call of cancel_work_sync() to the
destructor.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
99b2ab9d3a