Commit 0811ef7e authored Aug 11, 2016 by Mark Rutland Committed by Pawel Moll Aug 26, 2016

bus: arm-ccn: fix PMU interrupt flags



Currently the IRQ core is permitted to make the CCN PMU IRQ handler
threaded, and will allow userspace to change the CPU affinity of the
interrupt behind our back. Both of these could violate our
synchronisation requirements with the core perf code, which relies upon
strict CPU affinity and disabling of interrupts to guarantee mutual
exclusion in some cases.

As with the CPU PMU drivers, we should request the interrupt with
IRQF_NOBALANCING and IRQF_NO_THREAD, to avoid these issues.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Pawel Moll <pawel.moll@arm.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Pawel Moll <pawel.moll@arm.com>

parent 3249bce4

drivers/bus/arm-ccn.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -1496,7 +1496,8 @@ static int arm_ccn_probe(struct platform_device *pdev)
		/* Can set 'disable' bits, so can acknowledge interrupts */
		writel(CCN_MN_ERRINT_STATUS__PMU_EVENTS__ENABLE,
		ccn->base + CCN_MN_ERRINT_STATUS);
		err = devm_request_irq(ccn->dev, irq, arm_ccn_irq_handler, 0,
		err = devm_request_irq(ccn->dev, irq, arm_ccn_irq_handler,
		IRQF_NOBALANCING \| IRQF_NO_THREAD,
		dev_name(ccn->dev), ccn);
		if (err)
		return err;

Admin message