# Re: \[PATCH v2 2/3\] block: don't delete queue kobject before its children

- From: Hannes Reinecke \<hare@suse.de\>
- Date: 2021-11-30 06:46:01 
- List: linux-api
- Page: https://ratatoskr.run/linux-api/2021/11/1590897
- Thread: https://ratatoskr.run/linux-block/2021/11/1590823/t.md

```text
On 11/30/21 5:03 AM, Eric Biggers wrote:
> From: Eric Biggers <redacted>
>
> kobjects aren't supposed to be deleted before their child kobjects are
> deleted.  Apparently this is usually benign; however, a WARN will be
> triggered if one of the child kobjects has a named attribute group:
>
>      sysfs group 'modes' not found for kobject 'crypto'
>      WARNING: CPU: 0 PID: 1 at fs/sysfs/group.c:278 sysfs_remove_group+0x72/0x80
>      ...
>      Call Trace:
>        sysfs_remove_groups+0x29/0x40 fs/sysfs/group.c:312
>        __kobject_del+0x20/0x80 lib/kobject.c:611
>        kobject_cleanup+0xa4/0x140 lib/kobject.c:696
>        kobject_release lib/kobject.c:736 [inline]
>        kref_put include/linux/kref.h:65 [inline]
>        kobject_put+0x53/0x70 lib/kobject.c:753
>        blk_crypto_sysfs_unregister+0x10/0x20 block/blk-crypto-sysfs.c:159
>        blk_unregister_queue+0xb0/0x110 block/blk-sysfs.c:962
>        del_gendisk+0x117/0x250 block/genhd.c:610
>
> Fix this by moving the kobject_del() and the corresponding
> kobject_uevent() to the correct place.
>
> Fixes: 2c2086afc2b8 ("block: Protect less code with sysfs_lock in blk_{un,}register_queue()")
> Signed-off-by: Eric Biggers <redacted>
> ---
>   block/blk-sysfs.c | 8 +++++---
>   1 file changed, 5 insertions(+), 3 deletions(-)
>
Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
hare@suse.de                              +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer
```