blk_release_queue — release a struct request_queue when it is no longer needed
| void blk_release_queue ( | struct kobject * kobj ); | 
   blk_release_queue is the pair to blk_init_queue or
   blk_queue_make_request.  It should be called when a request queue is
   being released; typically when a block device is being de-registered.
   Currently, its primary task it to free all the struct request
   structures that were allocated to the queue and the queue itself.