[PATCH v2 2/2] block: Fix WARN_ON in blk_mq_run_hw_queue when called from interrupt context

[Ionut Nechita (WindRiver)]

From: Ionut Nechita <ionut.nechita@xxxxxxxxxxxxx>

Fix warning "WARN_ON_ONCE(!async && in_interrupt())" that occurs during
SCSI device scanning when blk_freeze_queue_start() calls blk_mq_run_hw_queues()
synchronously from interrupt context.

The issue happens during device removal/scanning when:
1. blk_mq_destroy_queue() -> blk_queue_start_drain()
2. blk_freeze_queue_start() calls blk_mq_run_hw_queues(q, false)
3. This triggers the warning in blk_mq_run_hw_queue() when in interrupt context

Change the synchronous call to asynchronous to avoid running in interrupt context.

Fixes: Warning in blk_mq_run_hw_queue+0x1fa/0x260
Signed-off-by: Ionut Nechita <ionut.nechita@xxxxxxxxxxxxx>
---
 block/blk-mq.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 5fb8da4958d0..ae152f7a6933 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -128,7 +128,7 @@ void blk_freeze_queue_start(struct request_queue *q)
 		percpu_ref_kill(&q->q_usage_counter);
 		mutex_unlock(&q->mq_freeze_lock);
 		if (queue_is_mq(q))
-			blk_mq_run_hw_queues(q, false);
+			blk_mq_run_hw_queues(q, true);
 	} else {
 		mutex_unlock(&q->mq_freeze_lock);
 	}
-- 
2.52.0