| Message ID | 1467136218-15789-2-git-send-email-mark.rutland@arm.com |
|---|---|
| State | New |
| Headers | show |
Dnia 2016-06-28, Tue o godzinie 18:50 +0100, Mark Rutland pisze: > 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> In principle, because still had no chance to test it... Thanks! Pawel _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
On Mon, Jul 04, 2016 at 02:39:44PM +0100, Pawel Moll wrote: > Dnia 2016-06-28, Tue o godzinie 18:50 +0100, Mark Rutland pisze: > > 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> Cheers. I've just sent v2, so I've applied that locally, and it'll appear if a v3 is necessary. > In principle, because still had no chance to test it... Understood. Thanks, Mark. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
diff --git a/drivers/bus/arm-ccn.c b/drivers/bus/arm-ccn.c index acc3eb5..2c99ab2 100644 --- a/drivers/bus/arm-ccn.c +++ b/drivers/bus/arm-ccn.c @@ -1479,8 +1479,9 @@ 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;
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> Cc: Marc Zyngier <marc.zyngier@arm.com> Cc: Pawel Moll <pawel.moll@arm.com> Cc: Suzuki K Poulose <suzuki.poulose@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Olof Johansson <olof@lixom.net> Cc: Arnd Bergmann <arnd@arndb.de> Cc: <arm@kernel.org> --- drivers/bus/arm-ccn.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) -- 1.9.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel