scsi: sd: Fix TCG OPAL unlock on system resume

Commit 3cc2ffe5c16d ("scsi: sd: Differentiate system and runtime start/stop
management") introduced the manage_system_start_stop scsi_device flag to
allow libata to indicate to the SCSI disk driver that nothing should be
done when resuming a disk on system resume. This change turned the
execution of sd_resume() into a no-op for ATA devices on system
resume. While this solved deadlock issues during device resume, this change
also wrongly removed the execution of opal_unlock_from_suspend().  As a
result, devices with TCG OPAL locking enabled remain locked and
inaccessible after a system resume from sleep.

To fix this issue, introduce the SCSI driver resume method and implement it
with the sd_resume() function calling opal_unlock_from_suspend(). The
former sd_resume() function is renamed to sd_resume_common() and modified
to call the new sd_resume() function. For non-ATA devices, this result in
no functional changes.

In order for libata to explicitly execute sd_resume() when a device is
resumed during system restart, the function scsi_resume_device() is
introduced. libata calls this function from the revalidation work executed
on devie resume, a state that is indicated with the new device flag
ATA_DFLAG_RESUMING. Doing so, locked TCG OPAL enabled devices are unlocked
on resume, allowing normal operation.

Fixes: 3cc2ffe5c16d ("scsi: sd: Differentiate system and runtime start/stop management")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=218538
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://lore.kernel.org/r/20240319071209.1179257-1-dlemoal@kernel.org
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 8d06475de17a..ffd7e7e72933 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -1642,6 +1642,40 @@ int scsi_add_device(struct Scsi_Host *host, uint channel,
 }
 EXPORT_SYMBOL(scsi_add_device);
 
+int scsi_resume_device(struct scsi_device *sdev)
+{
+	struct device *dev = &sdev->sdev_gendev;
+	int ret = 0;
+
+	device_lock(dev);
+
+	/*
+	 * Bail out if the device or its queue are not running. Otherwise,
+	 * the rescan may block waiting for commands to be executed, with us
+	 * holding the device lock. This can result in a potential deadlock
+	 * in the power management core code when system resume is on-going.
+	 */
+	if (sdev->sdev_state != SDEV_RUNNING ||
+	    blk_queue_pm_only(sdev->request_queue)) {
+		ret = -EWOULDBLOCK;
+		goto unlock;
+	}
+
+	if (dev->driver && try_module_get(dev->driver->owner)) {
+		struct scsi_driver *drv = to_scsi_driver(dev->driver);
+
+		if (drv->resume)
+			ret = drv->resume(dev);
+		module_put(dev->driver->owner);
+	}
+
+unlock:
+	device_unlock(dev);
+
+	return ret;
+}
+EXPORT_SYMBOL(scsi_resume_device);
+
 int scsi_rescan_device(struct scsi_device *sdev)
 {
 	struct device *dev = &sdev->sdev_gendev;