linux-kernel - [PATCH 4.9 84/93] nbd: blk_mq_init_queue returns an error code on failure, not NULL

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Date:   Wed,  9 Aug 2017 11:14:17 -0700
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jeff Moyer <jmoyer@...hat.com>,
        Omar Sandoval <osandov@...com>, Josef Bacik <jbacik@...com>,
        Jens Axboe <axboe@...com>,
        Sasha Levin <alexander.levin@...izon.com>
Subject: [PATCH 4.9 84/93] nbd: blk_mq_init_queue returns an error code on failure, not NULL

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jeff Moyer <jmoyer@...hat.com>


[ 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.

Signed-off-by: Jeff Moyer <jmoyer@...hat.com>
Reviewed-by: Omar Sandoval <osandov@...com>
Reviewed-by: Josef Bacik <jbacik@...com>
Signed-off-by: Jens Axboe <axboe@...com>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/block/nbd.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -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