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Subject: Re: [PATCH] kobject: hide illegible sysfs warning of kobject_del()
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
References: <20221111065807.3278713-1-liushixin2@huawei.com>
 <Y23rC0N1cL2LQpyF@kroah.com>
CC:     "Rafael J. Wysocki" <rafael@kernel.org>,
        <linux-kernel@vger.kernel.org>
From:   Liu Shixin <liushixin2@huawei.com>
Message-ID: <d89eb156-3db2-df72-d21c-357baba3d377@huawei.com>
Date:   Fri, 11 Nov 2022 16:27:03 +0800
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On 2022/11/11 14:26, Greg Kroah-Hartman wrote:
> On Fri, Nov 11, 2022 at 02:58:07PM +0800, Liu Shixin wrote:
>> Some consumers do not care whether kobject_add() succeed or failed such as
>> irqdesc. They call kobject_del() all the time even if kobject_add() failed.
>> Then kernel will report some illegible sysfs warning like this:
>>
>>  kernfs: can not remove 'actions', no directory
>>  WARNING: CPU: 0 PID: 277 at fs/kernfs/dir.c:1615 kernfs_remove_by_name_ns+0xd5/0xe0
> Why not fix the caller here?  Is that somehow not possible?
The caller should be freed by kobject_put() if kobject_add() failed. But in fact, the failure does not affect
the function of the caller. So the caller do not call kobject_put() Immediately.
If want to fix the caller, we can check konj->state_in_sysfs before call kobject_del(). This way has no difference
with check kobj->state_in_sysfs in kobject_del().
By the way, I'm not sure how many callers have this problem. So I think it's better to fix in kobject_del().

thanks,

>
> thanks,
>
> greg k-h
> .
>