linux-kernel - Re: [PATCH 01/11] kset: fix documentation for kset

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Date:   Fri, 21 Oct 2022 16:05:18 +0800
From:   Yang Yingliang <yangyingliang@...wei.com>
To:     Luben Tuikov <luben.tuikov@....com>,
        <linux-kernel@...r.kernel.org>, <qemu-devel@...gnu.org>,
        <linux-f2fs-devel@...ts.sourceforge.net>,
        <linux-erofs@...ts.ozlabs.org>, <ocfs2-devel@....oracle.com>,
        <linux-mtd@...ts.infradead.org>, <amd-gfx@...ts.freedesktop.org>,
        <gregkh@...uxfoundation.org>
CC:     <rafael@...nel.org>, <somlo@....edu>, <mst@...hat.com>,
        <jaegeuk@...nel.org>, <chao@...nel.org>,
        <hsiangkao@...ux.alibaba.com>, <huangjianan@...o.com>,
        <mark@...heh.com>, <jlbec@...lplan.org>,
        <joseph.qi@...ux.alibaba.com>, <akpm@...ux-foundation.org>,
        <alexander.deucher@....com>, <richard@....at>,
        <liushixin2@...wei.com>
Subject: Re: [PATCH 01/11] kset: fix documentation for kset_register()


On 2022/10/21 13:34, Luben Tuikov wrote:
> On 2022-10-20 22:20, Yang Yingliang wrote:
>> kset_register() is currently used in some places without calling
>> kset_put() in error path, because the callers think it should be
>> kset internal thing to do, but the driver core can not know what
>> caller doing with that memory at times. The memory could be freed
>> both in kset_put() and error path of caller, if it is called in
>> kset_register().
>>
>> So make the function documentation more explicit about calling
>> kset_put() in the error path of caller.
>>
>> Signed-off-by: Yang Yingliang <yangyingliang@...wei.com>
>> ---
>>   lib/kobject.c | 3 +++
>>   1 file changed, 3 insertions(+)
>>
>> diff --git a/lib/kobject.c b/lib/kobject.c
>> index a0b2dbfcfa23..6da04353d974 100644
>> --- a/lib/kobject.c
>> +++ b/lib/kobject.c
>> @@ -834,6 +834,9 @@ EXPORT_SYMBOL_GPL(kobj_sysfs_ops);
>>   /**
>>    * kset_register() - Initialize and add a kset.
>>    * @k: kset.
>> + *
>> + * If this function returns an error, kset_put() must be called to
>> + * properly clean up the memory associated with the object.
>>    */
> And I'd continue the sentence, with " ... with the object,
> for instance the memory for the kset.kobj.name when kobj_set_name(&kset.kobj, format, ...)
> was called before calling kset_register()."
kobject_cleanup() not only frees name, but aslo calls ->release() to 
free another resources.
>
> This makes it clear what we want to make sure is freed, in case of an early error
> from kset_register().

How about like this:

If this function returns an error, kset_put() must be called to clean up the name of
kset object and other memory associated with the object.

>
> Regards,
> Luben
>
>>   int kset_register(struct kset *k)
>>   {
> .