block: Make blk_cleanup_queue() wait until request_fn finished (24faf6f6) · Commits · 戴 / test

Some request_fn implementations, e.g. scsi_request_fn(), unlock the queue lock internally. This may result in multiple threads executing request_fn for the same queue simultaneously. Keep track of the number of active request_fn calls and make sure that blk_cleanup_queue() waits until all active request_fn invocations have finished. A block driver may start cleaning up resources needed by its request_fn as soon as blk_cleanup_queue() finished, so blk_cleanup_queue() must wait for all outstanding request_fn invocations to finish. Signed-off-by:

Bart Van Assche <bvanassche@acm.org> Reported-by:

Chanho Min <chanho.min@lge.com> Cc: James Bottomley <JBottomley@Parallels.com> Cc: Mike Christie <michaelc@cs.wisc.edu> Acked-by:

Tejun Heo <tj@kernel.org> Signed-off-by:

Jens Axboe <axboe@kernel.dk>

block/blk-core.c

+10 −0

Original line number	Diff line number	Diff line
		@@ -309,7 +309,16 @@ inline void __blk_run_queue_uncond(struct request_queue *q)
		if (unlikely(blk_queue_dead(q)))
		return;

		/*
		* Some request_fn implementations, e.g. scsi_request_fn(), unlock
		* the queue lock internally. As a result multiple threads may be
		* running such a request function concurrently. Keep track of the
		* number of active request_fn invocations such that blk_drain_queue()
		* can wait until all these request_fn calls have finished.
		*/
		q->request_fn_active++;
		q->request_fn(q);
		q->request_fn_active--;
		}

		/**
		@@ -408,6 +417,7 @@ static void __blk_drain_queue(struct request_queue *q, bool drain_all)
		__blk_run_queue(q);

		drain \|= q->nr_rqs_elvpriv;
		drain \|= q->request_fn_active;

		/*
		* Unfortunately, requests are queued at and tracked from

include/linux/blkdev.h

+6 −0

Original line number	Diff line number	Diff line
		@@ -378,6 +378,12 @@ struct request_queue {

		unsigned int nr_sorted;
		unsigned int in_flight[2];
		/*
		* Number of active block driver functions for which blk_drain_queue()
		* must wait. Must be incremented around functions that unlock the
		* queue_lock internally, e.g. scsi_request_fn().
		*/
		unsigned int request_fn_active;

		unsigned int rq_timeout;
		struct timer_list timeout;

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