From: Luben Tuikov <luben.tuikov@amd.com>
To: Yang Yingliang <yangyingliang@huawei.com>,
linux-kernel@vger.kernel.org, qemu-devel@nongnu.org,
linux-f2fs-devel@lists.sourceforge.net,
linux-erofs@lists.ozlabs.org, ocfs2-devel@oss.oracle.com,
linux-mtd@lists.infradead.org, amd-gfx@lists.freedesktop.org,
gregkh@linuxfoundation.org
Cc: rafael@kernel.org, somlo@cmu.edu, mst@redhat.com,
jaegeuk@kernel.org, chao@kernel.org, hsiangkao@linux.alibaba.com,
huangjianan@oppo.com, mark@fasheh.com, jlbec@evilplan.org,
joseph.qi@linux.alibaba.com, akpm@linux-foundation.org,
alexander.deucher@amd.com, richard@nod.at, liushixin2@huawei.com
Subject: Re: [PATCH 01/11] kset: fix documentation for kset_register()
Date: Fri, 21 Oct 2022 04:18:28 -0400 [thread overview]
Message-ID: <6df8844d-7f0c-17ac-96a4-beb981f2267c@amd.com> (raw)
In-Reply-To: <10d887c4-7db0-8958-f661-bd52e6c8b4af@huawei.com>
On 2022-10-21 04:05, Yang Yingliang wrote:
>
> 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@huawei.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.
Yes, it does. For this reason I said "for instance..." I didn't want to include
this in case in the future if the code changes, the comment would be wrong. IOW,
I wanted to add the minimalist comment possible.
>>
>> 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.
It's bit too wordy and redundant with what else it does--this can be gleaned
from the code. I'd say:
On error, kset_put() should be called to clean up at least kset.kobj.name allocated
by kobj_set_name(&kset.kobj, format, ...).
This tells the reader the symmetry of the calls: kobj_set_name() --> kset_register() --> kset_put();
Because if the code evolves to use other means of allocation, or if the the user allocates a name
by different means, then they'll understand what to watch out for.
Regards,
Luben
>
>>
>> Regards,
>> Luben
>>
>>> int kset_register(struct kset *k)
>>> {
>> .
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next prev parent reply other threads:[~2022-10-21 8:19 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-21 2:20 [PATCH 00/11] fix memory leak while kset_register() fails Yang Yingliang
2022-10-21 2:20 ` [PATCH 01/11] kset: fix documentation for kset_register() Yang Yingliang
2022-10-21 5:34 ` Luben Tuikov
2022-10-21 8:05 ` Yang Yingliang
2022-10-21 8:16 ` Greg KH
2022-10-21 8:18 ` Luben Tuikov [this message]
2022-10-21 2:20 ` [PATCH 02/11] kset: add null pointer check in kset_put() Yang Yingliang
2022-10-21 2:20 ` [PATCH 03/11] bus: fix possible memory leak in bus_register() Yang Yingliang
2022-10-21 2:20 ` [PATCH 04/11] kobject: fix possible memory leak in kset_create_and_add() Yang Yingliang
2022-10-21 2:20 ` [PATCH 05/11] class: fix possible memory leak in __class_register() Yang Yingliang
2022-10-21 2:20 ` [PATCH 06/11] firmware: qemu_fw_cfg: fix possible memory leak in fw_cfg_build_symlink() Yang Yingliang
2022-10-21 2:20 ` [PATCH 07/11] f2fs: fix possible memory leak in f2fs_init_sysfs() Yang Yingliang
2022-10-21 2:20 ` [PATCH 08/11] erofs: fix possible memory leak in erofs_init_sysfs() Yang Yingliang
2022-10-21 2:21 ` [PATCH 09/11] ocfs2: possible memory leak in mlog_sys_init() Yang Yingliang
2022-10-21 2:21 ` [PATCH 10/11] drm/amdgpu/discovery: fix possible memory leak Yang Yingliang
2022-10-21 2:21 ` [PATCH 11/11] ubifs: Fix memory leak in ubifs_sysfs_init() Yang Yingliang
2022-10-21 5:29 ` [PATCH 00/11] fix memory leak while kset_register() fails Luben Tuikov
2022-10-21 5:37 ` Greg KH
2022-10-21 7:55 ` Luben Tuikov
2022-10-21 8:18 ` Greg KH
2022-10-21 8:24 ` Luben Tuikov
2022-10-21 8:41 ` Luben Tuikov
2022-10-21 9:23 ` Yang Yingliang
2022-10-21 8:24 ` Yang Yingliang
2022-10-21 8:36 ` Greg KH
2022-10-21 8:52 ` Luben Tuikov
2022-10-21 8:59 ` Yang Yingliang
2022-10-21 9:08 ` Luben Tuikov
2022-10-21 9:56 ` Yang Yingliang
2022-10-21 23:45 ` Luben Tuikov
2022-10-21 9:12 ` Yang Yingliang
2022-10-21 23:48 ` Luben Tuikov
2022-10-21 7:25 ` Yang Yingliang
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