linux-kernel - [PATCH 1/2] floppy: Cleanup disk->queue before caling put_disk() if add

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Message-Id: <1327935591-26812-2-git-send-email-vgoyal@redhat.com>
Date:	Mon, 30 Jan 2012 09:59:50 -0500
From:	Vivek Goyal <vgoyal@...hat.com>
To:	linux-kernel@...r.kernel.org, axboe@...nel.dk
Cc:	tj@...nel.org, sjayaraman@...e.com,
	gouders@...bocholt.fh-gelsenkirchen.de, vgoyal@...hat.com
Subject: [PATCH 1/2] floppy: Cleanup disk->queue before caling put_disk() if add_disk() was never called

add_disk() takes gendisk reference on request queue. If driver failed during
initialization and never called add_disk() then that extra reference is not
taken. That reference is put in put_disk(). floppy driver allocates the
disk, allocates queue, sets disk->queue and then relizes that floppy
controller is not present. It tries to tear down everything and tries to
put a reference down in put_disk() which was never taken.

In such error cases cleanup disk->queue before calling put_disk() so that
we never try to put down a reference which was never taken in first place.

Reported-and-tested-by: Suresh Jayaraman <sjayaraman@...e.com>
Tested-by: Dirk Gouders <gouders@...bocholt.fh-gelsenkirchen.de>
Signed-off-by: Vivek Goyal <vgoyal@...hat.com>
Acked-by: Tejun Heo <tj@...nel.org>
---
 drivers/block/floppy.c |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)

diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
index 510fb10..401ba78 100644
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -4368,8 +4368,14 @@ out_unreg_blkdev:
 out_put_disk:
 	while (dr--) {
 		del_timer_sync(&motor_off_timer[dr]);
-		if (disks[dr]->queue)
+		if (disks[dr]->queue) {
 			blk_cleanup_queue(disks[dr]->queue);
+			/*
+			 * put_disk() is not paired with add_disk() and
+			 * will put queue reference one extra time. fix it.
+			 */
+			disks[dr]->queue = NULL;
+		}
 		put_disk(disks[dr]);
 	}
 	return err;
-- 
1.7.4.4

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