Messages in this thread | | | Date | Fri, 22 Oct 2021 16:05:24 +0100 | From | Mark Rutland <> | Subject | Re: [PATCH 01/15] irq: mips: avoid nested irq_enter() |
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On Fri, Oct 22, 2021 at 11:38:23AM +0100, Marc Zyngier wrote: > On Thu, 21 Oct 2021 19:02:22 +0100, > Mark Rutland <mark.rutland@arm.com> wrote: > > > > As bcm6345_l1_irq_handle() is a chained irqchip handler, it will be > > invoked within the context of the root irqchip handler, which must have > > entered IRQ context already. > > > > When bcm6345_l1_irq_handle() calls arch/mips's do_IRQ() , this will nest > > another call to irq_enter(), and the resulting nested increment to > > `rcu_data.dynticks_nmi_nesting` will cause rcu_is_cpu_rrupt_from_idle() > > to fail to identify wakeups from idle, resulting in failure to preempt, > > and RCU stalls. > > > > Chained irqchip handlers must invoke IRQ handlers by way of thee core > > irqchip code, i.e. generic_handle_irq() or generic_handle_domain_irq() > > and should not call do_IRQ(), which is intended only for root irqchip > > handlers. > > > > Fix bcm6345_l1_irq_handle() by calling generic_handle_irq() directly. > > > > Fixes: c7c42ec2baa1de7a ("irqchips/bmips: Add bcm6345-l1 interrupt controller") > > Signed-off-by: Mark Rutland <mark.rutland@arm.com> > > Cc: Marc Zyngier <maz@kernel.org> > > Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> > > Cc: Thomas Gleixner <tglx@linutronix.de> > > --- > > drivers/irqchip/irq-bcm6345-l1.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/irqchip/irq-bcm6345-l1.c b/drivers/irqchip/irq-bcm6345-l1.c > > index e3483789f4df..1bd0621c4ce2 100644 > > --- a/drivers/irqchip/irq-bcm6345-l1.c > > +++ b/drivers/irqchip/irq-bcm6345-l1.c > > @@ -140,7 +140,7 @@ static void bcm6345_l1_irq_handle(struct irq_desc *desc) > > for_each_set_bit(hwirq, &pending, IRQS_PER_WORD) { > > irq = irq_linear_revmap(intc->domain, base + hwirq); > > if (irq) > > - do_IRQ(irq); > > + generic_handle_irq(irq); > > else > > spurious_interrupt(); > > } > > A marginally better fix would be to have: > > diff --git a/drivers/irqchip/irq-bcm6345-l1.c b/drivers/irqchip/irq-bcm6345-l1.c > index 1bd0621c4ce2..fd079215c17f 100644 > --- a/drivers/irqchip/irq-bcm6345-l1.c > +++ b/drivers/irqchip/irq-bcm6345-l1.c > @@ -132,16 +132,12 @@ static void bcm6345_l1_irq_handle(struct irq_desc *desc) > int base = idx * IRQS_PER_WORD; > unsigned long pending; > irq_hw_number_t hwirq; > - unsigned int irq; > > pending = __raw_readl(cpu->map_base + reg_status(intc, idx)); > pending &= __raw_readl(cpu->map_base + reg_enable(intc, idx)); > > for_each_set_bit(hwirq, &pending, IRQS_PER_WORD) { > - irq = irq_linear_revmap(intc->domain, base + hwirq); > - if (irq) > - generic_handle_irq(irq); > - else > + if (generic_handle_domain_irq(intc->domain, base + hwirq)) > spurious_interrupt(); > } > } > > but we can also tackle that separately if you'd rather keep the change > minimal.
I'll add that to the series immediately after this patch, to keep this change minimal for backporting.
Thanks, Mark.
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