On Tue, 13 Jun 2017 22:32:52 +0300
Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
Hi Dan,
> Hello Marc Zyngier,
>
> This is a semi-automatic email about new static checker warnings.
>
> The patch fe17a42e704a: "irqdomain: Let irq_domain_mapping display
> hierarchical domains" from May 12, 2017, leads to the following
> Smatch complaint:
>
> kernel/irq/irqdomain.c:772 virq_debug_show_one()
> warn: variable dereferenced before check 'data' (see line 758)
>
> kernel/irq/irqdomain.c
> 757 while (domain) {
> 758 unsigned int irq = data->irq;
> ^^^^^^^^^
> Dereference.
>
> 759 unsigned long hwirq = data->hwirq;
> 760 struct irq_chip *chip;
> 761 bool direct;
> 762
> 763 if (data == &desc->irq_data)
> 764 seq_printf(m, "%5d ", irq);
> 765 else
> 766 seq_printf(m, "%5d+ ", irq);
> 767 seq_printf(m, "0x%05lx ", hwirq);
> 768
> 769 chip = irq_data_get_irq_chip(data);
> 770 seq_printf(m, "%-15s ", (chip && chip->name) ? chip->name : "none");
> 771
> 772 seq_printf(m, data ? "0x%p " : " %p ",
> ^^^^
> Too late to check.
This check is utter crap, and I should have nuked it when reworking
that code. We're guaranteed that if "data" becomes NULL at the end of
that loop, so will "domain". So the check is a leftover of... something.
I'll fix it in a subsequent patch, thanks a lot for the report.
M.
--
Without deviation from the norm, progress is not possible.
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