linux-kernel - [irqchip: irq/irqchip-next] irq: mips: avoid nested irq

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Date:   Tue, 26 Oct 2021 10:16:10 -0000
From:   "irqchip-bot for Mark Rutland" <tip-bot2@...utronix.de>
To:     linux-kernel@...r.kernel.org
Cc:     Mark Rutland <mark.rutland@....com>, Marc Zyngier <maz@...nel.org>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: [irqchip: irq/irqchip-next] irq: mips: avoid nested irq_enter()

The following commit has been merged into the irq/irqchip-next branch of irqchip:

Commit-ID:     c65b52d02f6c1a06ddb20cba175ad49eccd6410d
Gitweb:        https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms/c65b52d02f6c1a06ddb20cba175ad49eccd6410d
Author:        Mark Rutland <mark.rutland@....com>
AuthorDate:    Wed, 20 Oct 2021 17:25:22 +01:00
Committer:     Mark Rutland <mark.rutland@....com>
CommitterDate: Mon, 25 Oct 2021 10:01:39 +01:00

irq: mips: avoid nested irq_enter()

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@....com>
Reviewed-by: Marc Zyngier <maz@...nel.org>
Acked-by: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
Cc: Thomas Gleixner <tglx@...utronix.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 e348378..1bd0621 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();
 		}