[PATCH v6 09/23] scsi: sd: Do not issue commands to suspended disks on shutdown

[Damien Le Moal <dlemoal@kernel.org>]

If an error occurs when resuming a host adapter before the devices
attached to the adapter are resumed, the adapter low level driver may
remove the scsi host, resulting in a call to sd_remove() for the
disks of the host. This in turn results in a call to sd_shutdown() which
will issue a synchronize cache command and a start stop unit command to
spindown the disk. sd_shutdown() issues the commands only if the device
is not already runtime suspended but does not check the power state for
system-wide suspend/resume. That is, the commands may be issued with the
device in a suspended state, which causes PM resume to hang, forcing a
reset of the machine to recover.

Fix this by tracking the suspended state of a disk using the sicsi_disk
suspended flag and by not calling sd_shutdown() in sd_remove() if the
disk is not running.

Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
---
 drivers/scsi/sd.c | 17 +++++++++++++----
 drivers/scsi/sd.h |  1 +
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index a1ef4eef904f..bff8663be7e0 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -3741,7 +3741,8 @@ static int sd_remove(struct device *dev)
 
 	device_del(&sdkp->disk_dev);
 	del_gendisk(sdkp->disk);
-	sd_shutdown(dev);
+	if (!sdkp->suspended)
+		sd_shutdown(dev);
 
 	put_disk(sdkp->disk);
 	return 0;
@@ -3872,6 +3873,9 @@ static int sd_suspend_common(struct device *dev, bool runtime)
 			ret = 0;
 	}
 
+	if (!ret)
+		sdkp->suspended = 1;
+
 	return ret;
 }
 
@@ -3891,21 +3895,26 @@ static int sd_suspend_runtime(struct device *dev)
 static int sd_resume(struct device *dev, bool runtime)
 {
 	struct scsi_disk *sdkp = dev_get_drvdata(dev);
-	int ret;
+	int ret = 0;
 
 	if (!sdkp)	/* E.g.: runtime resume at the start of sd_probe() */
 		return 0;
 
-	if (!sd_do_start_stop(sdkp->device, runtime))
+	if (!sd_do_start_stop(sdkp->device, runtime)) {
+		sdkp->suspended = 0;
 		return 0;
+	}
 
 	if (!sdkp->device->no_start_on_resume) {
 		sd_printk(KERN_NOTICE, sdkp, "Starting disk\n");
 		ret = sd_start_stop_device(sdkp, 1);
 	}
 
-	if (!ret)
+	if (!ret) {
 		opal_unlock_from_suspend(sdkp->opal_dev);
+		sdkp->suspended = 0;
+	}
+
 	return ret;
 }
 
diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h
index 5eea762f84d1..4d42392fae07 100644
--- a/drivers/scsi/sd.h
+++ b/drivers/scsi/sd.h
@@ -150,6 +150,7 @@ struct scsi_disk {
 	unsigned	urswrz : 1;
 	unsigned	security : 1;
 	unsigned	ignore_medium_access_errors : 1;
+	unsigned	suspended : 1;
 };
 #define to_scsi_disk(obj) container_of(obj, struct scsi_disk, disk_dev)
 
-- 
2.41.0