Re: [PATCH RFC] Remove "spi-cs-high" property for GPIO-based chipselects

[Gerhard Sittig <gsi-ynQEQJNshbs@public.gmane.org>]

On Mon, Dec 02, 2013 at 19:03 +0100, Jonas Gorski wrote:
> 
> On Mon, Dec 2, 2013 at 3:54 PM, Alexander Shiyan <shc_work-JGs/UdohzUI@public.gmane.org> wrote:
> >> On Sun, Dec 1, 2013 at 8:59 AM, Alexander Shiyan <shc_work-JGs/UdohzUI@public.gmane.org> wrote:
> >> > This patch takes the CS active level from the GPIO bindings,
> >> > so we remove the special property "spi-cs-high" for chipselects
> >> > that use GPIO.
> > ...
> >
> >> > -       cs = devm_kzalloc(&master->dev,
> >> > -                         sizeof(int) * master->num_chipselect,
> >> > -                         GFP_KERNEL);
> >> > -       master->cs_gpios = cs;
> >> > +       master->cs_gpios = devm_kzalloc(&master->dev, master->num_chipselect *
> >> > +               (sizeof(int) + sizeof(enum of_gpio_flags)), GFP_KERNEL);
> >> >
> >> >         if (!master->cs_gpios)
> >> >                 return -ENOMEM;
> >> >
> >> >         for (i = 0; i < master->num_chipselect; i++)
> >> > -               cs[i] = -ENOENT;
> >> > +               master->cs_gpios[i] = -ENOENT;
> >> >
> >> >         for (i = 0; i < nb; i++)
> >> > -               cs[i] = of_get_named_gpio(np, "cs-gpios", i);
> >> > +               master->cs_gpios[i] =
> >> > +                       of_get_named_gpio_flags(np, "cs-gpios", i,
> >> > +                                               &master->cs_gpios_flags[i]);
> >>
> >> I don't see you initializing master->cs_gpio_flags anywhere, so won't
> >> this cause a null/unitialized pointer access?
> >
> > A few lines above. Memory is being allocated together with cs_gpios.
> 
> I see the allocation, but I don't see the assignment of
> master->cs_gpios_flags. Only master->cs_gpios gets assigned.

It's a side effect of the of_get_named_gpio_flags() call (passing
the variable by reference).

Don't worry, I felt the same when I read the patch.  Took me a
while to spot that everything was still in place. :)


virtually yours
Gerhard Sittig
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