linux-kernel - Re: [PATCH 02/25] staging: media: imx7-mipi-csis: fix pm_runtime_get

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Date:   Wed, 5 May 2021 16:23:28 +0200
From:   Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
To:     "Rui Miguel Silva" <rmfrfs@...il.com>
Cc:     "Jonathan Cameron" <Jonathan.Cameron@...wei.com>,
        <linuxarm@...wei.com>, <mauro.chehab@...wei.com>,
        "Fabio Estevam" <festevam@...il.com>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        "Mauro Carvalho Chehab" <mchehab@...nel.org>,
        "NXP Linux Team" <linux-imx@....com>,
        "Pengutronix Kernel Team" <kernel@...gutronix.de>,
        "Philipp Zabel" <p.zabel@...gutronix.de>,
        "Sascha Hauer" <s.hauer@...gutronix.de>,
        "Shawn Guo" <shawnguo@...nel.org>,
        "Steve Longerbeam" <slongerbeam@...il.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linux-media@...r.kernel.org>,
        <linux-staging@...ts.linux.dev>
Subject: Re: [PATCH 02/25] staging: media: imx7-mipi-csis: fix
 pm_runtime_get_sync() usage count

Em Wed, 05 May 2021 14:56:40 +0100
"Rui Miguel Silva" <rmfrfs@...il.com> escreveu:

> Hi,
> On Wed May 5, 2021 at 12:06 PM WEST, Jonathan Cameron wrote:
> 
> > On Wed, 5 May 2021 11:41:52 +0200
> > Mauro Carvalho Chehab <mchehab+huawei@...nel.org> wrote:
> >  
> > > The pm_runtime_get_sync() internally increments the
> > > dev->power.usage_count without decrementing it, even on errors.
> > > Replace it by the new pm_runtime_resume_and_get(), introduced by:
> > > commit dd8088d5a896 ("PM: runtime: Add pm_runtime_resume_and_get to deal with usage counter")
> > > in order to properly decrement the usage counter, avoiding
> > > a potential PM usage counter leak.
> > > 
> > > Acked-by: Rui Miguel Silva <rmfrfs@...il.com>
> > > Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>  
> >
> > Not a fix as far as I can see, just a cleanup - so perhaps not this set?  
> 
> yes, the original changelog of this patch, that I acked,  made it
> clear it was a cleanup:
> 
> "
> Commit dd8088d5a896 ("PM: runtime: Add pm_runtime_resume_and_get to
> deal with usage counter")                                                                                                                                         
> added pm_runtime_resume_and_get() in order to automatically handle 
> dev->power.usage_count decrement on errors.
> 
> Use the new API, in order to cleanup the error check logic.
> "
> 
> This one above is new, but I saw Mauro is going change it.

Yes, I'll change the subject/description to the
"use pm_runtime_resume_and_get()" one on this patch, as there's
no issue to be fixed here, just a cleanup ;-)

Sorry for the mess. I did lots of rebase on ~80 patch series
over the last couple of days, based on the reviews (and my own
internal reviews)...

See, the current patchset has ~80 patches with ~30% contained
fixes. It shows that writing a balanced PM runtime code is not
so trivial ;-)

Thanks,
Mauro