Patch "SCSI: fix crashes in sd and sr runtime PM" has been added to the 3.10-stable tree

This is a note to let you know that I've just added the patch titled

SCSI: fix crashes in sd and sr runtime PM

to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
scsi-fix-crashes-in-sd-and-sr-runtime-pm.patch
and it can be found in the queue-3.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Alan Stern <[email protected]>
Date: Wed, 20 Jan 2016 11:26:01 -0500
Subject: SCSI: fix crashes in sd and sr runtime PM

From: Alan Stern <[email protected]>

commit 13b4389143413a1f18127c07f72c74cad5b563e8 upstream.

Runtime suspend during driver probe and removal can cause problems. The driver's runtime_suspend or runtime_resume callbacks may invoked before the driver has finished binding to the device or after the driver has unbound from the device.

This problem shows up with the sd and sr drivers, and can cause disk or CD/DVD drives to become unusable as a result. The fix is simple. The drivers store a pointer to the scsi_disk or scsi_cd structure as their private device data when probing is finished, so we simply have to be sure to clear the private data during removal and test it during runtime suspend/resume.

This fixes <https://bugs.debian.org/801925>.

---
 drivers/scsi/sd.c |    7 +++++--
 drivers/scsi/sr.c |    4 ++++
 2 files changed, 9 insertions(+), 2 deletions(-)

@@ -3090,8 +3090,8 @@ static int sd_suspend(struct device *dev
 	struct scsi_disk *sdkp = scsi_disk_get_from_dev(dev);
 	int ret = 0;
 
-	if (!sdkp)
-		return 0;	/* this can happen */
+	if (!sdkp)	/* E.g.: runtime suspend following sd_remove() */
+		return 0;
 
 	if (sdkp->WCE) {
 		sd_printk(KERN_NOTICE, sdkp, "Synchronizing SCSI cache\n");

@@ -3115,6 +3115,9 @@ static int sd_resume(struct device *dev)
 	struct scsi_disk *sdkp = scsi_disk_get_from_dev(dev);
 	int ret = 0;
 
+	if (!sdkp)	/* E.g.: runtime resume at the start of sd_probe() */
+		return 0;
+
 	if (!sdkp->device->manage_start_stop)
 		goto done;
 

@@ -142,6 +142,9 @@ static int sr_runtime_suspend(struct dev
 {
 	struct scsi_cd *cd = dev_get_drvdata(dev);
 
+	if (!cd)	/* E.g.: runtime suspend following sr_remove() */
+		return 0;
+
 	if (cd->media_present)
 		return -EBUSY;
 	else

@@ -1006,6 +1009,7 @@ static int sr_remove(struct device *dev)
 
 	blk_queue_prep_rq(cd->device->request_queue, scsi_prep_fn);
 	del_gendisk(cd->disk);
+	dev_set_drvdata(dev, NULL);
 
 	mutex_lock(&sr_ref_mutex);
 	kref_put(&cd->kref, sr_kref_release);

Patches currently in stable-queue which might be from [email protected] are

queue-3.10/scsi-fix-null-pointer-dereference-in-runtime-pm.patch queue-3.10/scsi-fix-crashes-in-sd-and-sr-runtime-pm.patch