Re: [PATCH] gpio: pca953x: Survive spurious interrupts

[Marc Zyngier]

On 2020-10-07 13:02, Andy Shevchenko wrote:
> On Wed, Oct 7, 2020 at 12:49 PM Linus Walleij 
> <linus.walleij@xxxxxxxxxx> wrote:
> > On Mon, Oct 5, 2020 at 4:02 PM Marc Zyngier <maz@xxxxxxxxxx> wrote:
> >
> > > The pca953x driver never checks the result of irq_find_mapping(),
> > > which returns 0 when no mapping is found. When a spurious interrupt
> > > is delivered (which can happen under obscure circumstances), the
> > > kernel explodes as it still tries to handle the error code as
> > > a real interrupt.
> > >
> > > Handle this particular case and warn on spurious interrupts.
> > >
> > > Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
>
> Wait, doesn't actually [1]  fix the reported issue?

Not at all.

> Marc, can you confirm this?
>
> [1]: e43c26e12dd4 ("gpio: pca953x: Fix uninitialized pending variable")

Different bug, really. If an interrupt is *really* pending, and no
mapping established yet, feeding the result of irq_find_mapping() to
handle_nested_irq() will lead to a panic.

Recently seen on a Tegra system suffering from even more pathological 
bugs.

        M.
--
Jazz is not dead. It just smells funny...