| Message ID | 20211002162000.3708238-1-daniel@0x0f.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [RFC] gpiolib: Move setting the flow handler and don't set it at all if there is a parent domain | expand |
Hi Daniel, thanks for your patch! On Sat, Oct 2, 2021 at 6:20 PM Daniel Palmer <daniel@0x0f.com> wrote: > Calling irq_domain_set_info() before irq_domain_alloc_irqs_parent() > can cause a null pointer dereference as the parent domain isn't > ready yet. > > Move irq_domain_set_info() to after irq_domain_alloc_irqs_parent(). > A side effect of this is that irq_domain_set_info() will now overwrite > the flow handler from the parent domain. So if there is a parent > domain do not set the flow handler anymore. > > This allows gpio-msc313.c to level it's irq domain on top of the > new irq controller in later SigmaStar SoCs without crashing. > > Link: https://lore.kernel.org/linux-arm-kernel/20210914100415.1549208-1-daniel@0x0f.com/ > Signed-off-by: Daniel Palmer <daniel@0x0f.com> > Suggested-by: Marc Zyngier <maz@kernel.org> If Marc says this is the way to go I think it is the way to go! > kfree(parent_arg); > + > + if (!ret) { Please just exit on error so invert this. if (ret) return ret; and just de-indent the below code (easier to follow) > + /* If there is a parent domain leave the flow handler alone */ > + if (d->parent) > + irq_domain_set_hwirq_and_chip(d, > + irq, > + hwirq, > + gc->irq.chip, > + gc); > + /* Otherwise set the flow handler supplied by the gpio driver */ > + else > + irq_domain_set_info(d, > + irq, > + hwirq, > + gc->irq.chip, > + gc, > + girq->handler, > + NULL, NULL); > + irq_set_probe(irq); > + } Should we print an error if girq->handler is not NULL and we find a parent domain, like if (d->parent && girq->handler) dev_err(dev, "parent domain and flow handler both specified\n"); Yours, Linus Walleij
Hi Linus, On Mon, 4 Oct 2021 at 07:16, Linus Walleij <linus.walleij@linaro.org> wrote: > If Marc says this is the way to go I think it is the way to go! To be completely transparent, moving irq_domain_set_info() is from Marc. Not setting the handler is from me. > > > kfree(parent_arg); > > + > > + if (!ret) { > > Please just exit on error so invert this. Ok. > if (ret) > return ret; > > and just de-indent the below code (easier to follow) > > > + /* If there is a parent domain leave the flow handler alone */ > > + if (d->parent) > > Should we print an error if girq->handler is not NULL and we find > a parent domain, like > if (d->parent && girq->handler) > dev_err(dev, "parent domain and flow handler both specified\n"); I think that would help catch situations where these changes would break stuff. I want to avoid breaking other people's stuff for my hobby project. However, I've noticed we can't get to the "if (d->parent)" if there is no parent as irq_domain_alloc_irqs_parent() will return -ENOSYS if d->parent is null. So the logic isn't right there. I think the idea is right but now I can't figure out what we should actually check to know whether we need to set the handler or not. I'm hoping Marc will chip in when he has some time. :) Cheers, Daniel
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index d1b9b721218f..993eeced6b4f 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -1103,19 +1103,6 @@ static int gpiochip_hierarchy_irq_domain_alloc(struct irq_domain *d, } chip_dbg(gc, "found parent hwirq %u\n", parent_hwirq); - /* - * We set handle_bad_irq because the .set_type() should - * always be invoked and set the right type of handler. - */ - irq_domain_set_info(d, - irq, - hwirq, - gc->irq.chip, - gc, - girq->handler, - NULL, NULL); - irq_set_probe(irq); - /* This parent only handles asserted level IRQs */ parent_arg = girq->populate_parent_alloc_arg(gc, parent_hwirq, parent_type); if (!parent_arg) @@ -1137,6 +1124,27 @@ static int gpiochip_hierarchy_irq_domain_alloc(struct irq_domain *d, parent_hwirq, hwirq); kfree(parent_arg); + + if (!ret) { + /* If there is a parent domain leave the flow handler alone */ + if (d->parent) + irq_domain_set_hwirq_and_chip(d, + irq, + hwirq, + gc->irq.chip, + gc); + /* Otherwise set the flow handler supplied by the gpio driver */ + else + irq_domain_set_info(d, + irq, + hwirq, + gc->irq.chip, + gc, + girq->handler, + NULL, NULL); + irq_set_probe(irq); + } + return ret; }
Calling irq_domain_set_info() before irq_domain_alloc_irqs_parent() can cause a null pointer dereference as the parent domain isn't ready yet. Move irq_domain_set_info() to after irq_domain_alloc_irqs_parent(). A side effect of this is that irq_domain_set_info() will now overwrite the flow handler from the parent domain. So if there is a parent domain do not set the flow handler anymore. This allows gpio-msc313.c to level it's irq domain on top of the new irq controller in later SigmaStar SoCs without crashing. Link: https://lore.kernel.org/linux-arm-kernel/20210914100415.1549208-1-daniel@0x0f.com/ Signed-off-by: Daniel Palmer <daniel@0x0f.com> Suggested-by: Marc Zyngier <maz@kernel.org> --- drivers/gpio/gpiolib.c | 34 +++++++++++++++++++++------------- 1 file changed, 21 insertions(+), 13 deletions(-)