Patch "nbd: blk_mq_init_queue returns an error code on failure, not NULL" has been added to the 4.9-stable tree

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

nbd: blk_mq_init_queue returns an error code on failure, not NULL

to the 4.9-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:
nbd-blk_mq_init_queue-returns-an-error-code-on-failure-not-null.patch
and it can be found in the queue-4.9 subdirectory.

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

From: Jeff Moyer <[email protected]>
Date: Mon, 9 Jan 2017 15:20:31 -0500
Subject: nbd: blk_mq_init_queue returns an error code on failure, not NULL

From: Jeff Moyer <[email protected]>

[ Upstream commit 25b4acfc7de0fc4da3bfea3a316f7282c6fbde81 ]

Additionally, don't assign directly to disk->queue, otherwise blk_put_queue (called via put_disk) will choke (panic) on the errno stored there.

Bug found by code inspection after Omar found a similar issue in virtio_blk. Compile-tested only.

---
 drivers/block/nbd.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

@@ -929,6 +929,7 @@ static int __init nbd_init(void)
 		return -ENOMEM;
 
 	for (i = 0; i < nbds_max; i++) {
+		struct request_queue *q;
 		struct gendisk *disk = alloc_disk(1 << part_shift);
 		if (!disk)
 			goto out;

@@ -954,12 +955,13 @@ static int __init nbd_init(void)
 		 * every gendisk to have its very own request_queue struct.
 		 * These structs are big so we dynamically allocate them.
 		 */
-		disk->queue = blk_mq_init_queue(&nbd_dev[i].tag_set);
-		if (!disk->queue) {
+		q = blk_mq_init_queue(&nbd_dev[i].tag_set);
+		if (IS_ERR(q)) {
 			blk_mq_free_tag_set(&nbd_dev[i].tag_set);
 			put_disk(disk);
 			goto out;
 		}
+		disk->queue = q;
 
 		/*
 		 * Tell the block layer that we are not a rotational device

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

queue-4.9/nbd-blk_mq_init_queue-returns-an-error-code-on-failure-not-null.patch queue-4.9/virtio_blk-fix-panic-in-initialization-error-path.patch