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Message-ID: <cc219a52-e89c-b7e7-5bfd-0124f881a29f@linux.alibaba.com>
Date: Thu, 6 Apr 2023 18:13:05 +0800
From: Gao Xiang <hsiangkao@...ux.alibaba.com>
To: Greg KH <gregkh@...uxfoundation.org>,
Yangtao Li <frank.li@...o.com>
Cc: xiang@...nel.org, chao@...nel.org, huyue2@...lpad.com,
jefflexu@...ux.alibaba.com, damien.lemoal@...nsource.wdc.com,
naohiro.aota@....com, jth@...nel.org, rafael@...nel.org,
linux-erofs@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH 2/3] erofs: convert to use kobject_is_added()
Hi Greg,
On 2023/4/6 18:03, Greg KH wrote:
> On Thu, Apr 06, 2023 at 05:30:55PM +0800, Yangtao Li wrote:
>> Use kobject_is_added() instead of directly accessing the internal
>> variables of kobject. BTW kill kobject_del() directly, because
>> kobject_put() actually covers kobject removal automatically.
>>
>> Signed-off-by: Yangtao Li <frank.li@...o.com>
>> ---
>> fs/erofs/sysfs.c | 3 +--
>> 1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/fs/erofs/sysfs.c b/fs/erofs/sysfs.c
>> index 435e515c0792..daac23e32026 100644
>> --- a/fs/erofs/sysfs.c
>> +++ b/fs/erofs/sysfs.c
>> @@ -240,8 +240,7 @@ void erofs_unregister_sysfs(struct super_block *sb)
>> {
>> struct erofs_sb_info *sbi = EROFS_SB(sb);
>>
>> - if (sbi->s_kobj.state_in_sysfs) {
>> - kobject_del(&sbi->s_kobj);
>> + if (kobject_is_added(&sbi->s_kobj)) {
>
> I do not understand why this check is even needed, I do not think it
> should be there at all as obviously the kobject was registered if it now
> needs to not be registered.
I think Yangtao sent a new patchset which missed the whole previous
background discussions as below:
https://lore.kernel.org/r/028a1b56-72c9-75f6-fb68-1dc5181bf2e8@linux.alibaba.com
It's needed because once a syzbot complaint as below:
https://lore.kernel.org/r/CAD-N9QXNx=p3-QoWzk6pCznF32CZy8kM3vvo8mamfZZ9CpUKdw@mail.gmail.com
I'd suggest including the previous backgrounds at least in the newer patchset,
otherwise it makes me explain again and again...
Thanks,
Gao Xiang
>
> Meta-comment, we need to come up with a "filesystem kobject type" to get
> rid of lots of the boilerplate filesystem kobject logic as it's
> duplicated in every filesystem in tiny different ways and lots of times
> (like here), it's wrong.
>
> kobjects were not designed to be "used raw" like this, ideally they
> would be wrapped in a subsystem that makes them easier to be used (like
> the driver model), but filesystems decided to use them and that usage
> just grew over the years. That's evolution for you...>
> thanks,
>
> greg k-h
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