[Adding the person who introduced the code]
On Sun, 24 Feb 2013, Russell King - ARM Linux wrote:
> On Sun, Feb 24, 2013 at 12:45:11PM +0100, Julia Lawall wrote:
> > The function s3c24xx_irq_map in arch/arm/mach-s3c24xx/irq.c contains the
> > code:
> >
> > parent_irq_data = &parent_intc->irqs[irq_data->parent_irq];
> > if (!irq_data) {
> > pr_err("irq-s3c24xx: no irq data found for hwirq
> > %lu\n",
> > hw);
> > goto err;
> > }
> >
> > At this point irq_data has already been tested, so the null test on
> > irq_data does not look correct. But I wonder if parent_irq_data could
> > ever be null here?
>
> That would be really obscure - because that would require parent_intc to
> be a "negative" pointer (to counter-act the indexing by
> irq_data->parent_irq). So it looks to me like the above is redundant.
Even at its original definition irq_data seems unlikely to be NULL:
struct s3c_irq_intc *intc = h->host_data;
struct s3c_irq_data *irq_data = &intc->irqs[hw];
...
if (!irq_data) {
pr_err("irq-s3c24xx: no irq data found for hwirq %lu\n", hw);
return -EINVAL;
}
That is, it could be an invalid value, but whether it actually hits 0
would seem to depend on the value hw?
Heiko, is NULL really a possibility?
thanks,
julia
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