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authorBart Van Assche <bvanassche@acm.org>2020-12-08 21:29:44 -0800
committerMartin K. Petersen <martin.petersen@oracle.com>2020-12-09 11:41:41 -0500
commitfa4d0f1992a96f6d7c988ef423e3127e613f6ac9 (patch)
treeb784a47d8ba80c48b4fbe1e463e0eab14248b077
parentdd78bdb6f810bdcb173b42379af558c676c8e0aa (diff)
scsi: block: Fix a race in the runtime power management code
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. Link: https://lore.kernel.org/r/20201209052951.16136-2-bvanassche@acm.org Fixes: 986d413b7c15 ("blk-mq: Enable support for runtime power management") Cc: Ming Lei <ming.lei@redhat.com> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: stable <stable@vger.kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Jens Axboe <axboe@kernel.dk> Acked-by: Alan Stern <stern@rowland.harvard.edu> Acked-by: Stanley Chu <stanley.chu@mediatek.com> Co-developed-by: Can Guo <cang@codeaurora.org> Signed-off-by: Can Guo <cang@codeaurora.org> Signed-off-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
-rw-r--r--block/blk-pm.c15
1 files 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;
}