Patch "scsi: scsi_dh_alua: Fix a reference counting bug" has been added to the 4.8-stable tree

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

scsi: scsi_dh_alua: Fix a reference counting bug

to the 4.8-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-scsi_dh_alua-fix-a-reference-counting-bug.patch
and it can be found in the queue-4.8 subdirectory.

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

From: Bart Van Assche <[email protected]>
Date: Tue, 1 Nov 2016 08:19:57 -0600
Subject: scsi: scsi_dh_alua: Fix a reference counting bug

From: Bart Van Assche <[email protected]>

commit df3d422cbac685da882e4c239dfda07de33d431b upstream.

The code at the end of alua_rtpg_work() is as follows:

	scsi_device_put(sdev);
	kref_put(&pg->kref, release_port_group);

In other words, alua_rtpg_queue() must hold an sdev reference and a pg reference before queueing rtpg work. If no rtpg work is queued no additional references should be held when alua_rtpg_queue() returns. If no rtpg work is queued, ensure that alua_rtpg_queue() only gives up the sdev reference if that reference was obtained by the same alua_rtpg_queue() call.

---
 drivers/scsi/device_handler/scsi_dh_alua.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

@@ -890,6 +890,7 @@ static void alua_rtpg_queue(struct alua_
 		/* Do not queue if the worker is already running */
 		if (!(pg->flags & ALUA_PG_RUNNING)) {
 			kref_get(&pg->kref);
+			sdev = NULL;
 			start_queue = 1;
 		}
 	}

@@ -901,7 +902,8 @@ static void alua_rtpg_queue(struct alua_
 	if (start_queue &&
 	    !queue_delayed_work(alua_wq, &pg->rtpg_work,
 				msecs_to_jiffies(ALUA_RTPG_DELAY_MSECS))) {
-		scsi_device_put(sdev);
+		if (sdev)
+			scsi_device_put(sdev);
 		kref_put(&pg->kref, release_port_group);
 	}
 }

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

queue-4.8/scsi-scsi_dh_alua-fix-a-reference-counting-bug.patch