Re: [PATCH 0/4] blk-mq: support to use hw tag for scheduling

On Wed, 2017-05-03 at 11:07 -0600, Jens Axboe wrote:

+void blk_mq_stop_hw_queues(struct request_queue *q)
+{
+	__blk_mq_stop_hw_queues(q, false);
 }
 EXPORT_SYMBOL(blk_mq_stop_hw_queues);

Hello Jens,

So the approach of this patch is to make all blk_mq_stop_hw_queue()
and blk_mq_stop_hw_queues() callers cancel run_work without waiting?
That should make the BUG reported by Ming disappear. However, I think
we may want to review all calls from block drivers to
blk_mq_stop_hw_queues(). There are drivers that call this function to
quiesce I/O so I think these need the synchronous work cancellation ...

Bart.=