* [PATCH v3 1/9] block: Fix a race in the runtime power management code
[not found] <20201123031749.14912-1-bvanassche@acm.org>
@ 2020-11-23 3:17 ` Bart Van Assche
2020-11-23 6:46 ` Hannes Reinecke
0 siblings, 1 reply; 2+ messages in thread
From: Bart Van Assche @ 2020-11-23 3:17 UTC (permalink / raw)
To: Martin K . Petersen
Cc: James E . J . Bottomley, Jens Axboe, Christoph Hellwig, Ming Lei,
linux-scsi, linux-block, Bart Van Assche, Alan Stern,
Stanley Chu, Rafael J . Wysocki, stable, Can Guo
With the current implementation the following race can happen:
* blk_pre_runtime_suspend() calls blk_freeze_queue_start() and
blk_mq_unfreeze_queue().
* blk_queue_enter() calls blk_queue_pm_only() and that function returns
true.
* blk_queue_enter() calls blk_pm_request_resume() and that function does
not call pm_request_resume() because the queue runtime status is
RPM_ACTIVE.
* blk_pre_runtime_suspend() changes the queue status into RPM_SUSPENDING.
Fix this race by changing the queue runtime status into RPM_SUSPENDING
before switching q_usage_counter to atomic mode.
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Stanley Chu <stanley.chu@mediatek.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: stable <stable@vger.kernel.org>
Fixes: 986d413b7c15 ("blk-mq: Enable support for runtime power management")
Signed-off-by: Can Guo <cang@codeaurora.org>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
block/blk-pm.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/block/blk-pm.c b/block/blk-pm.c
index b85234d758f7..17bd020268d4 100644
--- a/block/blk-pm.c
+++ b/block/blk-pm.c
@@ -67,6 +67,10 @@ int blk_pre_runtime_suspend(struct request_queue *q)
WARN_ON_ONCE(q->rpm_status != RPM_ACTIVE);
+ spin_lock_irq(&q->queue_lock);
+ q->rpm_status = RPM_SUSPENDING;
+ spin_unlock_irq(&q->queue_lock);
+
/*
* Increase the pm_only counter before checking whether any
* non-PM blk_queue_enter() calls are in progress to avoid that any
@@ -89,15 +93,14 @@ int blk_pre_runtime_suspend(struct request_queue *q)
/* Switch q_usage_counter back to per-cpu mode. */
blk_mq_unfreeze_queue(q);
- spin_lock_irq(&q->queue_lock);
- if (ret < 0)
+ if (ret < 0) {
+ spin_lock_irq(&q->queue_lock);
+ q->rpm_status = RPM_ACTIVE;
pm_runtime_mark_last_busy(q->dev);
- else
- q->rpm_status = RPM_SUSPENDING;
- spin_unlock_irq(&q->queue_lock);
+ spin_unlock_irq(&q->queue_lock);
- if (ret)
blk_clear_pm_only(q);
+ }
return ret;
}
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v3 1/9] block: Fix a race in the runtime power management code
2020-11-23 3:17 ` [PATCH v3 1/9] block: Fix a race in the runtime power management code Bart Van Assche
@ 2020-11-23 6:46 ` Hannes Reinecke
0 siblings, 0 replies; 2+ messages in thread
From: Hannes Reinecke @ 2020-11-23 6:46 UTC (permalink / raw)
To: Bart Van Assche, Martin K . Petersen
Cc: James E . J . Bottomley, Jens Axboe, Christoph Hellwig, Ming Lei,
linux-scsi, linux-block, Alan Stern, Stanley Chu,
Rafael J . Wysocki, stable, Can Guo
On 11/23/20 4:17 AM, Bart Van Assche wrote:
> With the current implementation the following race can happen:
> * blk_pre_runtime_suspend() calls blk_freeze_queue_start() and
> blk_mq_unfreeze_queue().
> * blk_queue_enter() calls blk_queue_pm_only() and that function returns
> true.
> * blk_queue_enter() calls blk_pm_request_resume() and that function does
> not call pm_request_resume() because the queue runtime status is
> RPM_ACTIVE.
> * blk_pre_runtime_suspend() changes the queue status into RPM_SUSPENDING.
>
> Fix this race by changing the queue runtime status into RPM_SUSPENDING
> before switching q_usage_counter to atomic mode.
>
> Acked-by: Alan Stern <stern@rowland.harvard.edu>
> Acked-by: Stanley Chu <stanley.chu@mediatek.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Cc: Ming Lei <ming.lei@redhat.com>
> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> Cc: stable <stable@vger.kernel.org>
> Fixes: 986d413b7c15 ("blk-mq: Enable support for runtime power management")
> Signed-off-by: Can Guo <cang@codeaurora.org>
> Signed-off-by: Bart Van Assche <bvanassche@acm.org>
> ---
> block/blk-pm.c | 15 +++++++++------
> 1 file changed, 9 insertions(+), 6 deletions(-)
>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Cheers,
Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
hare@suse.de +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2020-11-23 6:46 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
[not found] <20201123031749.14912-1-bvanassche@acm.org>
2020-11-23 3:17 ` [PATCH v3 1/9] block: Fix a race in the runtime power management code Bart Van Assche
2020-11-23 6:46 ` Hannes Reinecke
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).