Re: [PATCH v2 1/1] mux: mux-core: Add NULL check for dev->of_node

[Kuppuswamy, Sathyanarayanan]

Hi Peter,


On 7/8/2017 2:00 PM, Peter Rosin wrote:
> On 2017-07-07 23:46, sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx wrote:
> > From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
> >
> > If dev->of_node is NULL, then calling mux_control_get()
> > function can lead to NULL pointer exception. So adding
> > a NULL check for dev->of_node.
> >
> > Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
> Do you have a driver that might call mux_control_get and not have any
> of_node?
For non-device tree drivers, this case is valid. I hit this issue when I 
was working on Intel USB MUX driver.
>   If not, I don't see the point of this check.
Since this is an API for other consumers, I think its better to have 
some sanity checks.

If a non device tree driver call this API , I think its better to fail 
with some error no instead of creating null pointer exception.
> Cheers,
> peda
>
> > ---
> >   drivers/mux/mux-core.c | 3 +++
> >   1 file changed, 3 insertions(+)
> >
> > Changes since v1:
> >   * Removed dummy new line.
> >
> > diff --git a/drivers/mux/mux-core.c b/drivers/mux/mux-core.c
> > index 90b8995..924c983 100644
> > --- a/drivers/mux/mux-core.c
> > +++ b/drivers/mux/mux-core.c
> > @@ -438,6 +438,9 @@ struct mux_control *mux_control_get(struct device *dev, const char *mux_name)
> >   	int index = 0;
> >   	int ret;
> >   
> > +	if (!np)
> > +		return ERR_PTR(-ENODEV);
> > +
> >   	if (mux_name) {
> >   		index = of_property_match_string(np, "mux-control-names",
> >   						 mux_name);