From: Christoph Hellwig <hch@lst.de>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: [PATCH 1/2] block: use an atomic_t for mq_freeze_depth
Date: Thu, 7 May 2015 09:38:13 +0200 [thread overview]
Message-ID: <1430984294-25859-2-git-send-email-hch@lst.de> (raw)
In-Reply-To: <1430984294-25859-1-git-send-email-hch@lst.de>
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>
---
block/blk-mq.c | 24 ++++++++++--------------
include/linux/blkdev.h | 2 +-
2 files changed, 11 insertions(+), 15 deletions(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index ade8a2d..9f554bb 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -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);
}
@@ -2047,7 +2043,7 @@ 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);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index a7f7c23..a10bed8 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -443,7 +443,7 @@ 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;
--
1.9.1
next prev parent reply other threads:[~2015-05-07 7:39 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-07 7:38 fix queue_lock usage in blk-mq and nvme Christoph Hellwig
2015-05-07 7:38 ` Christoph Hellwig [this message]
2015-05-07 7:38 ` [PATCH 2/2] nvme: disable irqs in nvme_freeze_queues Christoph Hellwig
2015-05-19 6:37 ` fix queue_lock usage in blk-mq and nvme Christoph Hellwig
2015-05-19 15:14 ` Jens Axboe
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