linux-kernel - [PATCH 3.16 095/410] pktcdvd: Fix pkt_setup

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Message-ID: <lsq.1528380321.25123677@decadent.org.uk>
Date:   Thu, 07 Jun 2018 15:05:21 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Jens Axboe" <axboe@...nel.dk>,
        "Maciej S. Szmigiero" <mail@...iej.szmigiero.name>,
        "Tejun Heo" <tj@...nel.org>,
        "Bart Van Assche" <bart.vanassche@....com>
Subject: [PATCH 3.16 095/410] pktcdvd: Fix pkt_setup_dev() error path

3.16.57-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Bart Van Assche <bart.vanassche@....com>

commit 5a0ec388ef0f6e33841aeb810d7fa23f049ec4cd upstream.

Commit 523e1d399ce0 ("block: make gendisk hold a reference to its queue")
modified add_disk() and disk_release() but did not update any of the
error paths that trigger a put_disk() call after disk->queue has been
assigned. That introduced the following behavior in the pktcdvd driver
if pkt_new_dev() fails:

Kernel BUG at 00000000e98fd882 [verbose debug info unavailable]

Since disk_release() calls blk_put_queue() anyway if disk->queue != NULL,
fix this by removing the blk_cleanup_queue() call from the pkt_setup_dev()
error path.

Fixes: commit 523e1d399ce0 ("block: make gendisk hold a reference to its queue")
Signed-off-by: Bart Van Assche <bart.vanassche@....com>
Cc: Tejun Heo <tj@...nel.org>
Cc: Maciej S. Szmigiero <mail@...iej.szmigiero.name>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/block/pktcdvd.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

--- a/drivers/block/pktcdvd.c
+++ b/drivers/block/pktcdvd.c
@@ -2796,7 +2796,7 @@ static int pkt_setup_dev(dev_t dev, dev_
 	pd->pkt_dev = MKDEV(pktdev_major, idx);
 	ret = pkt_new_dev(pd, dev);
 	if (ret)
-		goto out_new_dev;
+		goto out_mem2;
 
 	/* inherit events of the host device */
 	disk->events = pd->bdev->bd_disk->events;
@@ -2814,8 +2814,6 @@ static int pkt_setup_dev(dev_t dev, dev_
 	mutex_unlock(&ctl_mutex);
 	return 0;
 
-out_new_dev:
-	blk_cleanup_queue(disk->queue);
 out_mem2:
 	put_disk(disk);
 out_mem: