modprobe loop; rmmod loop effectively creates a blk_queue and destroys it
which results in q->unplug_work being canceled without it ever being
initialized.
Therefore, move the initialization of q->unplug_work from
blk_queue_make_request() to blk_alloc_queue*().
Reported-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
        init_timer(&q->unplug_timer);
        setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q);
        INIT_LIST_HEAD(&q->timeout_list);
+       INIT_WORK(&q->unplug_work, blk_unplug_work);
 
        kobject_init(&q->kobj, &blk_queue_ktype);
 
 
        if (q->unplug_delay == 0)
                q->unplug_delay = 1;
 
-       INIT_WORK(&q->unplug_work, blk_unplug_work);
-
        q->unplug_timer.function = blk_unplug_timeout;
        q->unplug_timer.data = (unsigned long)q;