Commit a538cd03 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
Browse files

block: merge blk_invoke_request_fn() into __blk_run_queue() 



__blk_run_queue wraps blk_invoke_request_fn() such that it
additionally removes plug and bails out early if the queue is empty.
Both extra operations have their own pending mechanisms and don't
cause any harm correctness-wise when they are done superflously.

The only user of blk_invoke_request_fn() being blk_start_queue(),
there isn't much reason to keep both functions around.  Merge
blk_invoke_request_fn() into __blk_run_queue() and make
blk_start_queue() use __blk_run_queue() instead.

[ Impact: merge two subtly different internal functions ]

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent db2dbb12

block/blk-core.c

+14 −21
Original line number Diff line number Diff line
@@ -333,24 +333,6 @@ void blk_unplug(struct request_queue *q) 
}

EXPORT_SYMBOL(blk_unplug);



static void blk_invoke_request_fn(struct request_queue *q)

{

	if (unlikely(blk_queue_stopped(q)))

		return;



	/*

	 * one level of recursion is ok and is much faster than kicking

	 * the unplug handling

	 */

	if (!queue_flag_test_and_set(QUEUE_FLAG_REENTER, q)) {

		q->request_fn(q);

		queue_flag_clear(QUEUE_FLAG_REENTER, q);

	} else {

		queue_flag_set(QUEUE_FLAG_PLUGGED, q);

		kblockd_schedule_work(q, &q->unplug_work);

	}

}



/**

 * blk_start_queue - restart a previously stopped queue

 * @q:    The &struct request_queue in question
@@ -365,7 +347,7 @@ void blk_start_queue(struct request_queue *q) 
	WARN_ON(!irqs_disabled());



	queue_flag_clear(QUEUE_FLAG_STOPPED, q);

	blk_invoke_request_fn(q);

	__blk_run_queue(q);

}

EXPORT_SYMBOL(blk_start_queue);
@@ -425,12 +407,23 @@ void __blk_run_queue(struct request_queue *q) 
{

	blk_remove_plug(q);



	if (unlikely(blk_queue_stopped(q)))

		return;



	if (elv_queue_empty(q))

		return;



	/*

	 * Only recurse once to avoid overrunning the stack, let the unplug

	 * handling reinvoke the handler shortly if we already got there.

	 */

	if (!elv_queue_empty(q))

		blk_invoke_request_fn(q);

	if (!queue_flag_test_and_set(QUEUE_FLAG_REENTER, q)) {

		q->request_fn(q);

		queue_flag_clear(QUEUE_FLAG_REENTER, q);

	} else {

		queue_flag_set(QUEUE_FLAG_PLUGGED, q);

		kblockd_schedule_work(q, &q->unplug_work);

	}

}

EXPORT_SYMBOL(__blk_run_queue);

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