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block: use an atomic_t for mq_freeze_depth

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lockdep gets unhappy about the not disabling irqs when using the queue_lock
around it.  Instead of trying to fix that up just switch to an atomic_t
and get rid of the lock.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Christoph Hellwig 2015-05-07 09:38:13 +02:00 committed by Jens Axboe
parent 5b3f341f09
commit 4ecd4fef3a
2 changed files with 11 additions and 15 deletions
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24
block/blk-mq.c
View File

@ -89,7 +89,8 @@ static int blk_mq_queue_enter(struct request_queue *q, gfp_t gfp)
return -EBUSY;
ret = wait_event_interruptible(q->mq_freeze_wq,
!q->mq_freeze_depth || blk_queue_dying(q));
!atomic_read(&q->mq_freeze_depth) ||
blk_queue_dying(q));
if (blk_queue_dying(q))
return -ENODEV;
if (ret)
@ -112,13 +113,10 @@ static void blk_mq_usage_counter_release(struct percpu_ref *ref)
void blk_mq_freeze_queue_start(struct request_queue *q)
{
bool freeze;
int freeze_depth;
spin_lock_irq(q->queue_lock);
freeze = !q->mq_freeze_depth++;
spin_unlock_irq(q->queue_lock);
if (freeze) {
freeze_depth = atomic_inc_return(&q->mq_freeze_depth);
if (freeze_depth == 1) {
percpu_ref_kill(&q->mq_usage_counter);
blk_mq_run_hw_queues(q, false);
}
@ -143,13 +141,11 @@ EXPORT_SYMBOL_GPL(blk_mq_freeze_queue);
void blk_mq_unfreeze_queue(struct request_queue *q)
{
bool wake;
int freeze_depth;
spin_lock_irq(q->queue_lock);
wake = !--q->mq_freeze_depth;
WARN_ON_ONCE(q->mq_freeze_depth < 0);
spin_unlock_irq(q->queue_lock);
if (wake) {
freeze_depth = atomic_dec_return(&q->mq_freeze_depth);
WARN_ON_ONCE(freeze_depth < 0);
if (!freeze_depth) {
percpu_ref_reinit(&q->mq_usage_counter);
wake_up_all(&q->mq_freeze_wq);
}
@ -2081,7 +2077,7 @@ void blk_mq_free_queue(struct request_queue *q)
/* Basically redo blk_mq_init_queue with queue frozen */
static void blk_mq_queue_reinit(struct request_queue *q)
{
WARN_ON_ONCE(!q->mq_freeze_depth);
WARN_ON_ONCE(!atomic_read(&q->mq_freeze_depth));
blk_mq_sysfs_unregister(q);

2
include/linux/blkdev.h
View File

@ -444,7 +444,7 @@ struct request_queue {
struct mutex sysfs_lock;
int bypass_depth;
int mq_freeze_depth;
atomic_t mq_freeze_depth;
#if defined(CONFIG_BLK_DEV_BSG)
bsg_job_fn *bsg_job_fn;