Re: [PATCH 2/4] arch/arm/mach-at91/clock.c: Add missing IS_ERR test

Vasiliy Kulikov
2011-01-24T20:05:26Z

On Mon, Jan 24, 2011 at 21:00 +0100, Julia Lawall wrote:
> On Tue, 25 Jan 2011, Ryan Mallon wrote:
>
> > On 01/25/2011 08:55 AM, Julia Lawall wrote:
> > > @@ -224,7 +224,7 @@ void __init at91_clock_associate(const char *id, struct device *dev, const char
> > > {
> > > struct clk *clk = clk_get(NULL, id);
> > >
> > > - if (!dev || !clk || !IS_ERR(clk_get(dev, func)))
> > > + if (!dev || IS_ERR(clk) || !IS_ERR(clk_get(dev, func)))
> > > return;
> >
> > I think we want:
> >
> > if (!dev || !clk || IS_ERR(clk) || !IS_ERR(clk_get(dev, func)))
> > return;
> >
> > Since it is valid to return a NULL clk, and we don't want to try and
> > dereference it if that is the case.
>
> Looking at the given defintion of clk_get, I can't see how that could
> happen:

clk_get() is defined per-architecture, sometimes it is NULL only.

> struct clk *clk_get(struct device *dev, const char *id)
> {
> struct clk *clk;
>
> list_for_each_entry(clk, &clocks, node) {
> if (strcmp(id, clk->name) == 0)
> return clk;
> if (clk->function && (dev == clk->dev) && strcmp(id, clk->function) == 0)
> return clk;
> }
>
> return ERR_PTR(-ENOENT);
> }
>
> Both paths to the non-ERR_PTR return dereference clk.
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--
Vasiliy