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

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Date:   Fri, 23 Apr 2021 10:10:19 +0200
From:   Hans Verkuil <hverkuil-cisco@...all.nl>
To:     Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        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 10:07, 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.

	Hans

> 
> Regards,
> Mauro
>