Re: [PATCH V3 1/6] blk-mq: grab .q_usage_counter when queuing request from plug code path

[Bart Van Assche <bvanassche@xxxxxxx>]

On Thu, 2019-04-04 at 00:27 +-0800, Ming Lei wrote:
+AD4 blk+AF8-mq+AF8-flush+AF8-plug+AF8-list():
+AD4 	blk+AF8-mq+AF8-sched+AF8-insert+AF8-requests()
+AD4 		insert requests to sw queue or scheduler queue 
+AD4 		blk+AF8-mq+AF8-run+AF8-hw+AF8-queue
+AD4 
+AD4 Because of concurrent run queue, all requests inserted above may be completed
+AD4 before calling the above blk+AF8-mq+AF8-run+AF8-hw+AF8-queue. Then queue can be freed
+AD4 during the above blk+AF8-mq+AF8-run+AF8-hw+AF8-queue().

Thanks for the clarification. That makes sense to me.

Bart.