From: Tejun Heo <tj@kernel.org>
To: Jens Axboe <jaxboe@fusionio.com>
Cc: linux-kernel@vger.kernel.org, kay.sievers@vrfy.org, hch@infradead.org
Subject: block: Fix oops caused by __blkdev_get() calling disk_unblock_events() with invalid @disk
Date: Wed, 9 Mar 2011 16:38:59 +0100 [thread overview]
Message-ID: <20110309153859.GD27010@htj.dyndns.org> (raw)
In-Reply-To: <4D779396.7050905@fusionio.com>
Commit 57c966b8b2 (block: Don't check events while open is in
progress) made __blkdev_get() block events around open calls; however,
it used invalid @disk pointer in the following cases.
* When ->open() returns -ERESTARTSYS, disk_unblock_events() is called
after @disk is put. @disk may be invalid by the time unblock is
called.
This is fixed by moving references after disk_unblock_events().
* When there are multiple openers, @disk is cleared to %NULL and later
disk_unblock_disk() is called with %NULL @disk causing oops.
This is fixed by moving reference putting after open success is
determined and not clearing @disk to %NULL. On success, @disk is
valid because there is another opener holding reference to it. On
failure, the references are put after disk_unblock_events() is
called.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Jens Axboe <axboe@kernel.dk>
---
Ah, sorry about that. My test setup didn't include a device with
multiple partitions on it so the more than one opener case never
triggered.
Thanks.
fs/block_dev.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)
Index: work/fs/block_dev.c
===================================================================
--- work.orig/fs/block_dev.c
+++ work/fs/block_dev.c
@@ -1109,11 +1109,11 @@ static int __blkdev_get(struct block_dev
*/
disk_put_part(bdev->bd_part);
bdev->bd_part = NULL;
- module_put(disk->fops->owner);
- put_disk(disk);
bdev->bd_disk = NULL;
mutex_unlock(&bdev->bd_mutex);
disk_unblock_events(disk);
+ module_put(disk->fops->owner);
+ put_disk(disk);
goto restart;
}
if (ret)
@@ -1150,9 +1150,6 @@ static int __blkdev_get(struct block_dev
bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9);
}
} else {
- module_put(disk->fops->owner);
- put_disk(disk);
- disk = NULL;
if (bdev->bd_contains == bdev) {
if (bdev->bd_disk->fops->open) {
ret = bdev->bd_disk->fops->open(bdev, mode);
@@ -1162,6 +1159,9 @@ static int __blkdev_get(struct block_dev
if (bdev->bd_invalidated)
rescan_partitions(bdev->bd_disk, bdev);
}
+ /* only one opener holds refs to the module and disk */
+ module_put(disk->fops->owner);
+ put_disk(disk);
}
bdev->bd_openers++;
if (for_part)
@@ -1182,8 +1182,7 @@ static int __blkdev_get(struct block_dev
mutex_unlock(&bdev->bd_mutex);
disk_unblock_events(disk);
out:
- if (disk)
- module_put(disk->fops->owner);
+ module_put(disk->fops->owner);
put_disk(disk);
bdput(bdev);
next prev parent reply other threads:[~2011-03-09 15:41 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-09 9:13 [PATCHSET] block: Convert block drivers to ->check_events(), take#2 Tejun Heo
2011-03-09 9:13 ` [PATCH 01/16] block: Don't implicitly trigger event check on disk_unblock_events() Tejun Heo
2011-03-09 9:13 ` [PATCH 02/16] block: Don't check events on close unless it was blocked Tejun Heo
2011-03-09 9:13 ` [PATCH 03/16] block: Don't check events while open is in progress Tejun Heo
2011-03-09 9:13 ` [PATCH 04/16] ide: Convert to bdops->check_events() Tejun Heo
2011-03-09 22:17 ` David Miller
2011-03-09 9:13 ` [PATCH 05/16] floppy,{ami|ata}flop: " Tejun Heo
2011-03-09 9:13 ` [PATCH 06/16] gdrom,viocd: " Tejun Heo
2011-03-09 9:13 ` [PATCH 07/16] paride: " Tejun Heo
2011-03-09 9:13 ` [PATCH 08/16] dac960: " Tejun Heo
2011-03-09 9:13 ` [PATCH 09/16] swim[3]: " Tejun Heo
2011-03-10 0:10 ` Benjamin Herrenschmidt
2011-03-09 9:13 ` [PATCH 10/16] ub: " Tejun Heo
2011-03-09 16:46 ` Pete Zaitcev
2011-03-09 16:58 ` Tejun Heo
2011-03-09 9:13 ` [PATCH 11/16] xsysace: " Tejun Heo
2011-03-09 9:13 ` [PATCH 12/16] i2o_block: " Tejun Heo
2011-03-09 9:13 ` [PATCH 13/16] s390/tape_block: " Tejun Heo
2011-03-09 9:13 ` [PATCH 14/16] umem: Drop dummy ->media_changed() Tejun Heo
2011-03-09 9:13 ` [PATCH 15/16] pktcdvd: Convert to bdops->check_events() Tejun Heo
2011-03-09 9:13 ` [PATCH 16/16] staging: " Tejun Heo
2011-03-09 9:20 ` [PATCHSET] block: Convert block drivers to ->check_events(), take#2 Jens Axboe
2011-03-09 14:49 ` Jens Axboe
2011-03-09 15:38 ` Tejun Heo [this message]
2011-03-09 18:26 ` block: Fix oops caused by __blkdev_get() calling disk_unblock_events() with invalid @disk Jens Axboe
2011-03-09 18:59 ` Tejun Heo
2011-03-09 19:16 ` Jens Axboe
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