linux-kernel - Re: [PATCH 009/190] Revert "media: s5p-mfc: Fix a reference count leak"

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Message-ID: <ed2859a3-0051-5ef4-483c-9abd4fa81b22@canonical.com>
Date:   Fri, 23 Apr 2021 10:17:51 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
To:     Hans Verkuil <hverkuil-cisco@...all.nl>,
        Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, Qiushi Wu <wu000273@....edu>,
        Julia Lawall <julia.lawall@...ia.fr>
Subject: Re: [PATCH 009/190] Revert "media: s5p-mfc: Fix a reference count
 leak"

On 23/04/2021 10:10, Hans Verkuil wrote:
> On 23/04/2021 10:07, Mauro Carvalho Chehab wrote:
>> Em Fri, 23 Apr 2021 09:10:32 +0200
>> Greg Kroah-Hartman <gregkh@...uxfoundation.org> escreveu:
>>
>>> On Fri, Apr 23, 2021 at 09:04:27AM +0200, Krzysztof Kozlowski wrote:
>>>> On 21/04/2021 14:58, Greg Kroah-Hartman wrote:  
>>>>> This reverts commit 78741ce98c2e36188e2343434406b0e0bc50b0e7.
>>>>>
>>>>> Commits from @umn.edu addresses have been found to be submitted in "bad
>>>>> faith" to try to test the kernel community's ability to review "known
>>>>> malicious" changes.  The result of these submissions can be found in a
>>>>> paper published at the 42nd IEEE Symposium on Security and Privacy
>>>>> entitled, "Open Source Insecurity: Stealthily Introducing
>>>>> Vulnerabilities via Hypocrite Commits" written by Qiushi Wu (University
>>>>> of Minnesota) and Kangjie Lu (University of Minnesota).
>>>>>
>>>>> Because of this, all submissions from this group must be reverted from
>>>>> the kernel tree and will need to be re-reviewed again to determine if
>>>>> they actually are a valid fix.  Until that work is complete, remove this
>>>>> change to ensure that no problems are being introduced into the
>>>>> codebase.
>>>>>
>>>>> Cc: Qiushi Wu <wu000273@....edu>
>>>>> Cc: Hans Verkuil <hverkuil-cisco@...all.nl>
>>>>> Cc: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
>>>>> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
>>>>> ---
>>>>>  drivers/media/platform/s5p-mfc/s5p_mfc_pm.c | 4 +---
>>>>>  1 file changed, 1 insertion(+), 3 deletions(-)
>>>>>   
>>>>
>>>> This looks like a good commit but should be done now in a different way
>>>> - using pm_runtime_resume_and_get().  Therefore I am fine with revert
>>>> and I can submit later better fix.  
>>>
>>> Great, thanks for letting me know, I can have someone work on the
>>> "better fix" at the same time.
>>
>> IMO, it is better to keep the fix. I mean, there's no reason to
>> revert a fix that it is known to be good.
>>
>> The "better fix" patch can be produced anytime. A simple coccinelle
>> ruleset can replace patterns like:
>>
>> 	ret = pm_runtime_get_sync(pm->device);
>> 	if (ret < 0) {
>> 		pm_runtime_put_noidle(pm->device);
>> 		return ret;
>> 	}
>>
>> and the broken pattern:
>>
>> 	ret = pm_runtime_get_sync(pm->device);
>> 	if (ret < 0)
>> 		return ret;
>>
>> to:
>>
>> 	ret = pm_runtime_resume_and_get(pm->device);
>> 	if (ret < 0)
>> 		return ret;
> 
> That's my preference as well.

It won't be that easy because sometimes the error handling is via goto
(like in other patches here) but anyway I don't mind keeping the
original commits.

Best regards,
Krzysztof