linux-kernel - Re: [PATCH v1 2/3] media: cedrus: Set the platform driver data earlier

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Message-ID: <4733096.GXAFRqVoOG@jernej-laptop>
Date:   Sat, 20 Aug 2022 10:25:48 +0200
From:   Jernej Škrabec <jernej.skrabec@...il.com>
To:     linux-media@...r.kernel.org, Maxime Ripard <mripard@...nel.org>,
        Paul Kocialkowski <paul.kocialkowski@...tlin.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Chen-Yu Tsai <wens@...e.org>,
        Samuel Holland <samuel@...lland.org>,
        Nicolas Dufresne <nicolas.dufresne@...labora.com>
Cc:     kernel@...labora.com,
        Dmitry Osipenko <dmitry.osipenko@...labora.com>,
        stable@...r.kernel.org, linux-staging@...ts.linux.dev,
        linux-arm-kernel@...ts.infradead.org, linux-sunxi@...ts.linux.dev,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 2/3] media: cedrus: Set the platform driver data earlier

Dne petek, 19. avgust 2022 ob 17:37:20 CEST je Nicolas Dufresne napisal(a):
> Le vendredi 19 août 2022 à 06:17 +0200, Jernej Škrabec a écrit :
> > Dne četrtek, 18. avgust 2022 ob 22:33:07 CEST je Nicolas Dufresne 
napisal(a):
> > > From: Dmitry Osipenko <dmitry.osipenko@...labora.com>
> > > 
> > > The cedrus_hw_resume() crashes with NULL deference on driver probe if
> > > runtime PM is disabled because it uses platform data that hasn't been
> > > set up yet. Fix this by setting the platform data earlier during probe.
> > 
> > Does it even work without PM? Maybe it would be better if Cedrus would
> > select PM in Kconfig.
> 
> I cannot comment myself on this, but it does not seem to invalidate this
> Dmitry's fix.

If NULL pointer dereference happens only when PM is disabled, then it does. I 
have PM always enabled and I never experienced above issue.

Best regards,
Jernej

> 
> > Best regards,
> > Jernej
> > 
> > > Cc: stable@...r.kernel.org
> > > Signed-off-by: Dmitry Osipenko <dmitry.osipenko@...labora.com>
> > > Signed-off-by: Nicolas Dufresne <nicolas.dufresne@...labora.com>
> > > ---
> > > 
> > >  drivers/staging/media/sunxi/cedrus/cedrus.c | 4 ++--
> > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/drivers/staging/media/sunxi/cedrus/cedrus.c
> > > b/drivers/staging/media/sunxi/cedrus/cedrus.c index
> > > 960a0130cd620..55c54dfdc585c 100644
> > > --- a/drivers/staging/media/sunxi/cedrus/cedrus.c
> > > +++ b/drivers/staging/media/sunxi/cedrus/cedrus.c
> > > @@ -448,6 +448,8 @@ static int cedrus_probe(struct platform_device
> > > *pdev)
> > > 
> > >  	if (!dev)
> > >  	
> > >  		return -ENOMEM;
> > > 
> > > +	platform_set_drvdata(pdev, dev);
> > > +
> > > 
> > >  	dev->vfd = cedrus_video_device;
> > >  	dev->dev = &pdev->dev;
> > >  	dev->pdev = pdev;
> > > 
> > > @@ -521,8 +523,6 @@ static int cedrus_probe(struct platform_device
> > > *pdev)
> > > 
> > >  		goto err_m2m_mc;
> > >  	
> > >  	}
> > > 
> > > -	platform_set_drvdata(pdev, dev);
> > > -
> > > 
> > >  	return 0;
> > >  
> > >  err_m2m_mc: