[SCSI] remove a useless get/put_device pair in scsi_request_fn (613be1f6) · Commits · 戴 / test

SCSI devices may only be removed by calling scsi_remove_device(). That function must invoke blk_cleanup_queue() before the final put of sdev->sdev_gendev. Since blk_cleanup_queue() waits for the block queue to drain and then tears it down, scsi_request_fn cannot be active anymore after blk_cleanup_queue() has returned and hence the get_device()/put_device() pair in scsi_request_fn is unnecessary. Signed-off-by:

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

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

Hannes Reinecke <hare@suse.de> Reviewed-by:

Mike Christie <michaelc@cs.wisc.edu> Signed-off-by:

James Bottomley <JBottomley@Parallels.com>

drivers/scsi/scsi_lib.c

+3 −11

Original line number	Diff line number	Diff line
		@@ -1565,16 +1565,14 @@ static void scsi_softirq_done(struct request *rq)
		* Lock status: IO request lock assumed to be held when called.
		*/
		static void scsi_request_fn(struct request_queue *q)
		__releases(q->queue_lock)
		__acquires(q->queue_lock)
		{
		struct scsi_device *sdev = q->queuedata;
		struct Scsi_Host *shost;
		struct scsi_cmnd *cmd;
		struct request *req;

		if(!get_device(&sdev->sdev_gendev))
		/* We must be tearing the block queue down already */
		return;

		/*
		* To start with, we keep looping until the queue is empty, or until
		* the host is no longer able to accept any more requests.
		@@ -1663,7 +1661,7 @@ static void scsi_request_fn(struct request_queue *q)
		goto out_delay;
		}

		goto out;
		return;

		not_ready:
		spin_unlock_irq(shost->host_lock);
		@@ -1682,12 +1680,6 @@ static void scsi_request_fn(struct request_queue *q)
		out_delay:
		if (sdev->device_busy == 0)
		blk_delay_queue(q, SCSI_QUEUE_DELAY);
		out:
		/* must be careful here...if we trigger the ->remove() function
		* we cannot be holding the q lock */
		spin_unlock_irq(q->queue_lock);
		put_device(&sdev->sdev_gendev);
		spin_lock_irq(q->queue_lock);
		}

		u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)

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