[PATCH v2 3/3] scsi: sd: stop polling disk stats by ledtrig-blk during runtime suspend

[Akinobu Mita <akinobu.mita@gmail.com>]

The LED block device activity trigger periodically polls the disk stats
to collect the activity.  However, it is pointless to poll while the
scsi device is in runtime suspend.

This stops polling disk stats when the device is successfully runtime
suspended, and restarts polling when the device is successfully runtime
resumed.

Cc: Frank Steiner <fsteiner-mail1@bio.ifi.lmu.de>
Cc: Jacek Anaszewski <jacek.anaszewski@gmail.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Dan Murphy <dmurphy@ti.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "James E.J. Bottomley" <jejb@linux.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
---
 drivers/scsi/sd.c | 40 +++++++++++++++++++++++-----------------
 1 file changed, 23 insertions(+), 17 deletions(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 149d406..5f73142 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -3538,7 +3538,7 @@ static int sd_suspend_common(struct device *dev, bool ignore_stop_errors)
 {
 	struct scsi_disk *sdkp = dev_get_drvdata(dev);
 	struct scsi_sense_hdr sshdr;
-	int ret = 0;
+	int ret;
 
 	if (!sdkp)	/* E.g.: runtime suspend following sd_remove() */
 		return 0;
@@ -3550,18 +3550,16 @@ static int sd_suspend_common(struct device *dev, bool ignore_stop_errors)
 		if (ret) {
 			/* ignore OFFLINE device */
 			if (ret == -ENODEV)
-				return 0;
-
-			if (!scsi_sense_valid(&sshdr) ||
-			    sshdr.sense_key != ILLEGAL_REQUEST)
-				return ret;
+				goto success;
 
 			/*
 			 * sshdr.sense_key == ILLEGAL_REQUEST means this drive
 			 * doesn't support sync. There's not much to do and
 			 * suspend shouldn't fail.
 			 */
-			ret = 0;
+			if (!scsi_sense_valid(&sshdr) ||
+			    sshdr.sense_key != ILLEGAL_REQUEST)
+				return ret;
 		}
 	}
 
@@ -3569,11 +3567,14 @@ static int sd_suspend_common(struct device *dev, bool ignore_stop_errors)
 		sd_printk(KERN_NOTICE, sdkp, "Stopping disk\n");
 		/* an error is not worth aborting a system sleep */
 		ret = sd_start_stop_device(sdkp, 0);
-		if (ignore_stop_errors)
-			ret = 0;
+		if (ret && !ignore_stop_errors)
+			return ret;
 	}
 
-	return ret;
+success:
+	ledtrig_blk_disable(sdkp->disk);
+
+	return 0;
 }
 
 static int sd_suspend_system(struct device *dev)
@@ -3589,19 +3590,24 @@ static int sd_suspend_runtime(struct device *dev)
 static int sd_resume(struct device *dev)
 {
 	struct scsi_disk *sdkp = dev_get_drvdata(dev);
-	int ret;
 
 	if (!sdkp)	/* E.g.: runtime resume at the start of sd_probe() */
 		return 0;
 
-	if (!sdkp->device->manage_start_stop)
-		return 0;
+	if (sdkp->device->manage_start_stop) {
+		int ret;
+
+		sd_printk(KERN_NOTICE, sdkp, "Starting disk\n");
+		ret = sd_start_stop_device(sdkp, 1);
+		if (ret)
+			return ret;
 
-	sd_printk(KERN_NOTICE, sdkp, "Starting disk\n");
-	ret = sd_start_stop_device(sdkp, 1);
-	if (!ret)
 		opal_unlock_from_suspend(sdkp->opal_dev);
-	return ret;
+	}
+
+	ledtrig_blk_enable(sdkp->disk);
+
+	return 0;
 }
 
 /**
-- 
2.7.4