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* [PATCH] irqchip/apple-aic: fix irq_disable from within irq handlers
@ 2021-08-12 10:09 Sven Peter
  2021-08-18 11:35 ` Hector Martin
                   ` (2 more replies)
  0 siblings, 3 replies; 4+ messages in thread
From: Sven Peter @ 2021-08-12 10:09 UTC (permalink / raw)
  To: Hector Martin
  Cc: Sven Peter, Thomas Gleixner, Marc Zyngier, Will Deacon,
	linux-arm-kernel, linux-kernel

When disable_irq_nosync for an interrupt is called from within its
interrupt handler, this interrupt is only marked as disabled with the
intention to mask it when it triggers again.
The AIC hardware however automatically masks the interrupt when it is read.
aic_irq_eoi then unmasks it again if it's not disabled *and* not masked.
This results in a state mismatch between the hardware state and the
state kept in irq_data: The hardware interrupt is masked but
IRQD_IRQ_MASKED is not set. Any further calls to unmask_irq will directly
return and the interrupt can never be enabled again.

Fix this by keeping the hardware and irq_data state in sync by unmasking in
aic_irq_eoi if and only if the irq_data state also assumes the interrupt to
be unmasked.

Fixes: 76cde2639411 ("irqchip/apple-aic: Add support for the Apple Interrupt Controller")
Signed-off-by: Sven Peter <sven@svenpeter.dev>
---
 drivers/irqchip/irq-apple-aic.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/irqchip/irq-apple-aic.c b/drivers/irqchip/irq-apple-aic.c
index b8c06bd8659e..6fc145aacaf0 100644
--- a/drivers/irqchip/irq-apple-aic.c
+++ b/drivers/irqchip/irq-apple-aic.c
@@ -226,7 +226,7 @@ static void aic_irq_eoi(struct irq_data *d)
 	 * Reading the interrupt reason automatically acknowledges and masks
 	 * the IRQ, so we just unmask it here if needed.
 	 */
-	if (!irqd_irq_disabled(d) && !irqd_irq_masked(d))
+	if (!irqd_irq_masked(d))
 		aic_irq_unmask(d);
 }
 
-- 
2.25.1


^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2021-08-20 13:34 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-08-12 10:09 [PATCH] irqchip/apple-aic: fix irq_disable from within irq handlers Sven Peter
2021-08-18 11:35 ` Hector Martin
2021-08-20 12:22 ` Marc Zyngier
2021-08-20 13:34 ` [irqchip: irq/irqchip-next] irqchip/apple-aic: Fix " irqchip-bot for Sven Peter

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