[PATCH 2/4] ARM: common/locomo: remove NO_IRQ check

Arnd Bergmann
2016-09-06T14:50:02Z

On Tuesday, September 6, 2016 3:21:44 PM CEST Russell King - ARM Linux wrote:
> On Tue, Sep 06, 2016 at 03:53:28PM +0200, Arnd Bergmann wrote:
> > Since commit 489447380a29 ("[PATCH] handle errors returned by
> > platform_get_irq*()") ten years ago, the locomo driver refuses to
> > work without an interrupt line passed in its resources, so the
> > check for NO_IRQ is unnecessary.
>
> This description is inaccurate and misleading (it looks like it was
> cut'n'pasted from patch 1.)
>
> platform_get_irq() has nothing to do with your change, as your change
> is more about the irq_base value passed through platform data, and
> not through IRQ resources.

It was copied, but this part refers to this hunk

irq = platform_get_irq(dev, 0);
if (irq < 0)
return -ENXIO;

from locomo_probe that was changed in the same patch as
the on in sa1111.c

> > We still check the irq_base argument for NO_IRQ, but as both

where the irq_base comes in.

I'll try to reword this to make it clearer.

> > @@ -387,7 +389,7 @@ __locomo_probe(struct device *me, struct resource *mem, int irq)
> >
> > lchip->phys = mem->start;
> > lchip->irq = irq;
> > - lchip->irq_base = (pdata) ? pdata->irq_base : NO_IRQ;
> > + lchip->irq_base = pdata->irq_base;
>
> This removes a NULL pointer check. Before this change, a NULL pdata
> would be accepted and would lead to the interrupts not being setup.
> After this change, it results in a NULL pointer deference.
>
> Thankfully, both collie and poodle supply platform data, and are the
> only providers of the locomo device.

Right, that is what I tried to say above. With the check I've added
in __locomo_probe, it would actually get the NULL pointer dereference
earlier than this line. I'll add back that check earlier in the function
and return an error in that case.

Arnd