diff options
| author | Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com> | 2021-07-17 18:07:19 +0800 |
|---|---|---|
| committer | Miquel Raynal <miquel.raynal@bootlin.com> | 2021-08-06 21:44:16 +0200 |
| commit | b7abb051682263e51866bc78762fd0083d64c5ed (patch) | |
| tree | 713b1e0360420fb748de7623f88cb9e8eea10162 /drivers/mtd/mtd_blkdevs.c | |
| parent | 99dc4ad992bf156692b088fab4d98deab7cbd3e6 (diff) | |
mtd: fix lock hierarchy in deregister_mtd_blktrans
There is a lock hierarchy of major_names_lock --> mtd_table_mutex. One
existing chain is as follows:
1. major_names_lock --> loop_ctl_mutex (when blk_request_module calls
loop_probe)
2. loop_ctl_mutex --> bdev->bd_mutex (when loop_control_ioctl calls
loop_remove, which then calls del_gendisk)
3. bdev->bd_mutex --> mtd_table_mutex (when blkdev_get_by_dev calls
__blkdev_get, which then calls blktrans_open)
Since unregister_blkdev grabs the major_names_lock, we need to call it
outside the critical section for mtd_table_mutex, otherwise we invert
the lock hierarchy.
Reported-by: Hillf Danton <hdanton@sina.com>
Signed-off-by: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20210717100719.728829-1-desmondcheongzx@gmail.com
Diffstat (limited to 'drivers/mtd/mtd_blkdevs.c')
| -rw-r--r-- | drivers/mtd/mtd_blkdevs.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c index 31b208fb225e..44bea3f65060 100644 --- a/drivers/mtd/mtd_blkdevs.c +++ b/drivers/mtd/mtd_blkdevs.c @@ -561,8 +561,8 @@ int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr) list_for_each_entry_safe(dev, next, &tr->devs, list) tr->remove_dev(dev); - unregister_blkdev(tr->major, tr->name); mutex_unlock(&mtd_table_mutex); + unregister_blkdev(tr->major, tr->name); BUG_ON(!list_empty(&tr->devs)); return 0; |