block: add proper state guards to __elv_next_request

blk_cleanup_queue() calls elevator_exit() and after this, we can't
touch the elevator without oopsing.  __elv_next_request() must check
for this state because in the refcounted queue model, we can still
call it after blk_cleanup_queue() has been called.

This was reported as causing an oops attributable to scsi.

Signed-off-by: James Bottomley <James.Bottomley@suse.de>
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
This commit is contained in:
James Bottomley 2011-05-18 16:20:10 +02:00 committed by Jens Axboe
parent a2b9c1f620
commit 0a58e077eb

View file

@ -62,7 +62,8 @@ static inline struct request *__elv_next_request(struct request_queue *q)
return rq;
}
if (!q->elevator->ops->elevator_dispatch_fn(q, 0))
if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags) ||
!q->elevator->ops->elevator_dispatch_fn(q, 0))
return NULL;
}
}