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

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Message-ID: <20210423100727.5a999c2e@coco.lan>
Date:   Fri, 23 Apr 2021 10:07:27 +0200
From:   Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        linux-kernel@...r.kernel.org, Qiushi Wu <wu000273@....edu>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Julia Lawall <julia.lawall@...ia.fr>
Subject: Re: [PATCH 009/190] Revert "media: s5p-mfc: Fix a reference count
 leak"

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;

Regards,
Mauro