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Commit c1b707d2 authored by Jens Axboe's avatar Jens Axboe Committed by Linus Torvalds
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[PATCH] CFQ: bad locking in changed_ioprio() 



When the ioprio code recently got juggled a bit, a bug was introduced.
changed_ioprio() is no longer called with interrupts disabled, so using
plain spin_lock() on the queue_lock is a bug.

Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 0261d688

block/cfq-iosched.c

+3 −2
Original line number Diff line number Diff line
@@ -1215,11 +1215,12 @@ static inline void changed_ioprio(struct cfq_io_context *cic) 
{

	struct cfq_data *cfqd = cic->key;

	struct cfq_queue *cfqq;

	unsigned long flags;



	if (unlikely(!cfqd))

		return;



	spin_lock(cfqd->queue->queue_lock);

	spin_lock_irqsave(cfqd->queue->queue_lock, flags);



	cfqq = cic->cfqq[ASYNC];

	if (cfqq) {
@@ -1236,7 +1237,7 @@ static inline void changed_ioprio(struct cfq_io_context *cic) 
	if (cfqq)

		cfq_mark_cfqq_prio_changed(cfqq);



	spin_unlock(cfqd->queue->queue_lock);

	spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);

}



static void cfq_ioc_set_ioprio(struct io_context *ioc)