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>

diff --git a/drivers/bus/arm-ccn.c b/drivers/bus/arm-ccn.c
index 02f81e308dff5a2c4818004a4d80a8d3dee750a8..c826bb2860540b8ea2748f1eebcf4fe73e38efb7 100644 (file)
--- a/drivers/bus/arm-ccn.c
+++ b/drivers/bus/arm-ccn.c
@@ -1496,8 +1496,9 @@ 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,
-                               dev_name(ccn->dev), ccn);
+               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;