linux-kernel - Re: [PATCH v2 7/9] mfd: mfd-core: Protect against NULL call-back function pointer

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Date:   Mon, 21 Oct 2019 13:40:27 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     Daniel Thompson <daniel.thompson@...aro.org>
Cc:     arnd@...db.de, broonie@...nel.org, linus.walleij@...aro.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        baohua@...nel.org, stephan@...hold.net
Subject: Re: [PATCH v2 7/9] mfd: mfd-core: Protect against NULL call-back
 function pointer

On Mon, 21 Oct 2019, Daniel Thompson wrote:

> On Mon, Oct 21, 2019 at 11:58:20AM +0100, Lee Jones wrote:
> > If a child device calls mfd_cell_{en,dis}able() without an appropriate
> > call-back being set, we are likely to encounter a panic.  Avoid this
> > by adding suitable checking.
> > 
> > Signed-off-by: Lee Jones <lee.jones@...aro.org>
> > ---
> >  drivers/mfd/mfd-core.c | 10 ++++++++++
> >  1 file changed, 10 insertions(+)
> > 
> > diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c
> > index 8126665bb2d8..90b43b44a15a 100644
> > --- a/drivers/mfd/mfd-core.c
> > +++ b/drivers/mfd/mfd-core.c
> > @@ -28,6 +28,11 @@ int mfd_cell_enable(struct platform_device *pdev)
> >  	const struct mfd_cell *cell = mfd_get_cell(pdev);
> >  	int err = 0;
> >  
> > +	if (!cell->enable) {
> > +		dev_dbg(&pdev->dev, "No .enable() call-back registered\n");
> > +		return 0;
> > +	}
> > +
> >  	/* only call enable hook if the cell wasn't previously enabled */
> >  	if (atomic_inc_return(cell->usage_count) == 1)
> >  		err = cell->enable(pdev);
> > @@ -45,6 +50,11 @@ int mfd_cell_disable(struct platform_device *pdev)
> >  	const struct mfd_cell *cell = mfd_get_cell(pdev);
> >  	int err = 0;
> >  
> > +	if (!cell->enable) {
> 
> Oops.
> 
> Cancel the R-B: ;-). Shouldn't this be !cell->disable() ?

Yes. Looks like a C/P error.

Will fix and add your R-b.

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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