HID: fix waitqueue usage in hiddev
DECLARE_WAITQUEUE doesn't initialize the wait descriptor's task_list to 'empty' but to zero. prepare_to_wait() will not enqueue the descriptor to the waitqueue and finish_wait() will do list_del_init() on a list head that contains NULL pointers, which oopses. This was introduced by 07903407 "HID: hiddev cleanup -- handle all error conditions properly". The prior code used an unconditional add_to_waitqueue() which didn't care about the wait descriptor's list head and enqueued the thing unconditionally. The new code uses prepare_to_wait() which DOES check the prior list state, so use DEFINE_WAIT instead. Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org> Cc: Oliver Neukum <oliver@neukum.name> Cc: Jiri Kosina <jkosina@suse.cz> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NJiri Kosina <jkosina@suse.cz>
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