linux-kernel - [PATCH 2/6] block: allow blk_execute_rq_nowait() to be called form IRQ context

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Date:	Thu, 20 Oct 2011 20:56:36 -0700
From:	Tejun Heo <tj@...nel.org>
To:	axboe@...nel.dk, vgoyal@...hat.com, jgarzik@...ox.com,
	davem@...emloft.net
Cc:	linux-kernel@...r.kernel.org, ctalbott@...gle.com, rni@...gle.com,
	Tejun Heo <tj@...nel.org>
Subject: [PATCH 2/6] block: allow blk_execute_rq_nowait() to be called form IRQ context

Currently blk_execute_rq_nowait() directly calls __blk_run_queue() and
thus can't be called from IRQ context.  This patch updates it to use
blk_run_queue_async() instead.  This will be used to unexport
elv_add_request().

This changes how queue is kicked after blk_execute_rq_nowait() but
it's hardly a hot path and the effect shouldn't be noticeable.

Signed-off-by: Tejun Heo <tj@...nel.org>
Cc: Jens Axboe <axboe@...nel.dk>
---
 block/blk-exec.c |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/block/blk-exec.c b/block/blk-exec.c
index a1ebceb..056f097 100644
--- a/block/blk-exec.c
+++ b/block/blk-exec.c
@@ -49,6 +49,7 @@ void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk,
 			   rq_end_io_fn *done)
 {
 	int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK;
+	unsigned long flags;
 
 	if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) {
 		rq->errors = -ENXIO;
@@ -59,14 +60,13 @@ void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk,
 
 	rq->rq_disk = bd_disk;
 	rq->end_io = done;
-	WARN_ON(irqs_disabled());
-	spin_lock_irq(q->queue_lock);
+	spin_lock_irqsave(q->queue_lock, flags);
 	__elv_add_request(q, rq, where);
-	__blk_run_queue(q);
+	blk_run_queue_async(q);
 	/* the queue is stopped so it won't be run */
 	if (rq->cmd_type == REQ_TYPE_PM_RESUME)
 		q->request_fn(q);
-	spin_unlock_irq(q->queue_lock);
+	spin_unlock_irqrestore(q->queue_lock, flags);
 }
 EXPORT_SYMBOL_GPL(blk_execute_rq_nowait);
 
-- 
1.7.3.1

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