[PATCH v7 5/8] scsi: core: Rework scsi_single_lun_run()

[Bart Van Assche <bvanassche@acm.org>]

Use __starget_for_each_device() instead of open-coding
starget_for_each_device(). Run the queues asynchronously instead of
synchronously.

This patch removes code that calls scsi_device_put() from atomic context.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: John Garry <john.garry@huawei.com>
Cc: Mike Christie <michael.christie@oracle.com>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/scsi/scsi_lib.c | 32 +++++++++++++++-----------------
 1 file changed, 15 insertions(+), 17 deletions(-)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 8b89fab7c420..fa96d3cfdfa3 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -307,6 +307,18 @@ static void scsi_kick_queue(struct request_queue *q)
 	blk_mq_run_hw_queues(q, false);
 }
 
+/*
+ * Kick the queue of SCSI device @sdev if @sdev != current_sdev. Called with
+ * interrupts disabled.
+ */
+static void scsi_kick_sdev_queue(struct scsi_device *sdev, void *data)
+{
+	struct scsi_device *current_sdev = data;
+
+	if (sdev != current_sdev)
+		blk_mq_run_hw_queues(sdev->request_queue, true);
+}
+
 /*
  * Called for single_lun devices on IO completion. Clear starget_sdev_user,
  * and call blk_run_queue for all the scsi_devices on the target -
@@ -317,7 +329,6 @@ static void scsi_kick_queue(struct request_queue *q)
 static void scsi_single_lun_run(struct scsi_device *current_sdev)
 {
 	struct Scsi_Host *shost = current_sdev->host;
-	struct scsi_device *sdev, *tmp;
 	struct scsi_target *starget = scsi_target(current_sdev);
 	unsigned long flags;
 
@@ -334,22 +345,9 @@ static void scsi_single_lun_run(struct scsi_device *current_sdev)
 	scsi_kick_queue(current_sdev->request_queue);
 
 	spin_lock_irqsave(shost->host_lock, flags);
-	if (starget->starget_sdev_user)
-		goto out;
-	list_for_each_entry_safe(sdev, tmp, &starget->devices,
-			same_target_siblings) {
-		if (sdev == current_sdev)
-			continue;
-		if (scsi_device_get(sdev))
-			continue;
-
-		spin_unlock_irqrestore(shost->host_lock, flags);
-		scsi_kick_queue(sdev->request_queue);
-		spin_lock_irqsave(shost->host_lock, flags);
-
-		scsi_device_put(sdev);
-	}
- out:
+	if (!starget->starget_sdev_user)
+		__starget_for_each_device(starget, current_sdev,
+					  scsi_kick_sdev_queue);
 	spin_unlock_irqrestore(shost->host_lock, flags);
 }