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From: Julien Thierry <julien.thierry@arm.com>
To: Will Deacon <will@kernel.org>
Cc: mark.rutland@arm.com, peterz@infradead.org, liwei391@huawei.com,
	will.deacon@arm.com, Russell King <linux@armlinux.org.uk>,
	acme@kernel.org, alexander.shishkin@linux.intel.com,
	mingo@redhat.com, stable@vger.kernel.org, namhyung@kernel.org,
	sthotton@marvell.com, jolsa@redhat.com,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v4 3/9] arm: perf: save/resore pmsel
Date: Fri, 2 Aug 2019 15:34:20 +0100
Message-ID: <1a349743-8fcf-9f05-00b4-b5e31340854e@arm.com> (raw)
In-Reply-To: <20190801130126.xxsot2mabvisq76e@willie-the-truck>



On 01/08/2019 14:01, Will Deacon wrote:
> [typo in subject: resore ->restore]
> 
> On Wed, Jul 17, 2019 at 09:17:06AM +0100, Julien Thierry wrote:
>> The callback pmu->read() can be called with interrupts enabled.
>> Currently, on ARM, this can cause the following callchain:
>>
>> armpmu_read() -> armpmu_event_update() -> armv7pmu_read_counter()
> 
> Why can't we just disable irqs in armv7pmu_read_counter() ?
> 

We could. But since we get rid of the lock after (otherwise it is the
only reason we have to keep the lock) we might as well find another
solution.

Thanks,

-- 
Julien Thierry

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Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-17  8:17 [PATCH v4 0/9] arm_pmu: Use NMI for perf interrupt Julien Thierry
2019-07-17  8:17 ` [PATCH v4 1/9] arm64: perf: avoid PMXEV* indirection Julien Thierry
2019-07-17  8:17 ` [PATCH v4 2/9] arm64: perf: Remove PMU locking Julien Thierry
2019-08-01 12:58   ` Will Deacon
2019-08-02 14:26     ` Julien Thierry
2019-07-17  8:17 ` [PATCH v4 3/9] arm: perf: save/resore pmsel Julien Thierry
2019-08-01 13:01   ` Will Deacon
2019-08-02 14:34     ` Julien Thierry [this message]
2019-07-17  8:17 ` [PATCH v4 4/9] arm: perf: Remove Remove PMU locking Julien Thierry
2019-08-01 13:06   ` Will Deacon
2019-08-02 14:36     ` Julien Thierry
2019-07-17  8:17 ` [PATCH v4 5/9] perf/arm_pmu: Move PMU lock to ARMv6 events Julien Thierry
2019-07-17  8:17 ` [PATCH v4 6/9] arm64: perf: Do not call irq_work_run in NMI context Julien Thierry
2019-08-01 13:06   ` Will Deacon
2019-08-02 14:43     ` Julien Thierry
2019-07-17  8:17 ` [PATCH v4 7/9] arm/arm64: kvm: pmu: Make overflow handler NMI safe Julien Thierry
2019-07-17  8:17 ` [PATCH v4 8/9] arm_pmu: Introduce pmu_irq_ops Julien Thierry
2019-07-17  8:17 ` [PATCH v4 9/9] arm_pmu: Use NMIs for PMU Julien Thierry
2019-07-30  9:11   ` Russell King - ARM Linux admin
2019-07-30  9:18     ` Julien Thierry
2019-07-30  9:28       ` Russell King - ARM Linux admin
2019-07-30 14:06         ` Julien Thierry
2019-07-17  9:02 ` [PATCH v4 0/9] arm_pmu: Use NMI for perf interrupt Julien Thierry
2019-07-30  9:05 ` Julien Thierry

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