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From: Suzuki K Poulose <suzuki.poulose@arm.com>
To: robin.murphy@arm.com, will.deacon@arm.com, mark.rutland@arm.com
Cc: linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, peterz@infradead.org,
	tglx@linutronix.de, bigeasy@linutronix.de
Subject: Re: [PATCH 5/5] perf/arm_dsu: Fix CPU hotplug races
Date: Tue, 5 Feb 2019 11:40:31 +0000	[thread overview]
Message-ID: <9fcf862c-0d07-cece-852f-6c09128aa0c5@arm.com> (raw)
In-Reply-To: <d376f6bbd5804616b38145780789785b19a37543.1549299188.git.robin.murphy@arm.com>



On 04/02/2019 17:09, Robin Murphy wrote:
> Like other system PMUs which associate themselves with an arbitrary CPU
> for housekeeping purposes, arm_dsu has a race between registering the
> hotplug notifier and registering the PMU device, such that the hotplug
> niotifier can potentially fire and attempt to migrate the PMU context
> before the latter is valid. This is easily resolved by inhibiting
> hotplug until both the notifier and PMU device are successfully set up.
> 
> For the same reason, also suppress any synchronous notifier calls in the
> cleanup path if PMU registration fails.
> 
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>

Should we add :

Fixes: commit 7520fa99246dade7ab6 ("perf: ARM DynamIQ Shared Unit PMU support")

Either way:

Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>

WARNING: multiple messages have this Message-ID (diff)
From: Suzuki K Poulose <suzuki.poulose@arm.com>
To: robin.murphy@arm.com, will.deacon@arm.com, mark.rutland@arm.com
Cc: peterz@infradead.org, tglx@linutronix.de, bigeasy@linutronix.de,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 5/5] perf/arm_dsu: Fix CPU hotplug races
Date: Tue, 5 Feb 2019 11:40:31 +0000	[thread overview]
Message-ID: <9fcf862c-0d07-cece-852f-6c09128aa0c5@arm.com> (raw)
In-Reply-To: <d376f6bbd5804616b38145780789785b19a37543.1549299188.git.robin.murphy@arm.com>



On 04/02/2019 17:09, Robin Murphy wrote:
> Like other system PMUs which associate themselves with an arbitrary CPU
> for housekeeping purposes, arm_dsu has a race between registering the
> hotplug notifier and registering the PMU device, such that the hotplug
> niotifier can potentially fire and attempt to migrate the PMU context
> before the latter is valid. This is easily resolved by inhibiting
> hotplug until both the notifier and PMU device are successfully set up.
> 
> For the same reason, also suppress any synchronous notifier calls in the
> cleanup path if PMU registration fails.
> 
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>

Should we add :

Fixes: commit 7520fa99246dade7ab6 ("perf: ARM DynamIQ Shared Unit PMU support")

Either way:

Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>

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  reply	other threads:[~2019-02-05 11:40 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-04 17:09 [PATCH 0/5] Fix Arm system PMU hotplug issues Robin Murphy
2019-02-04 17:09 ` Robin Murphy
2019-02-04 17:09 ` [PATCH 1/5] perf/arm-cci: Fix CPU hotplug race avoidance Robin Murphy
2019-02-04 17:09   ` Robin Murphy
2019-02-05 10:10   ` Corentin Labbe
2019-02-05 10:10     ` Corentin Labbe
2019-02-05 11:19   ` Suzuki K Poulose
2019-02-05 11:19     ` Suzuki K Poulose
2019-02-10 20:43   ` Thomas Gleixner
2019-02-10 20:43     ` Thomas Gleixner
2019-02-04 17:09 ` [PATCH 2/5] cpu/hotplug: Export __cpuhp_state_add_instance_cpuslocked() Robin Murphy
2019-02-04 17:09   ` Robin Murphy
2019-02-04 17:09 ` [PATCH 3/5] perf/arm-ccn: Fix CPU hotplug race avoidance Robin Murphy
2019-02-04 17:09   ` Robin Murphy
2019-02-05 11:38   ` Suzuki K Poulose
2019-02-05 11:38     ` Suzuki K Poulose
2019-02-10 20:44   ` Thomas Gleixner
2019-02-10 20:44     ` Thomas Gleixner
2019-02-04 17:09 ` [PATCH 4/5] cpu/hotplug: Add locked variant of cpuhp_state_add_instance() Robin Murphy
2019-02-04 17:09   ` Robin Murphy
2019-02-04 17:09 ` [PATCH 5/5] perf/arm_dsu: Fix CPU hotplug races Robin Murphy
2019-02-04 17:09   ` Robin Murphy
2019-02-05 11:40   ` Suzuki K Poulose [this message]
2019-02-05 11:40     ` Suzuki K Poulose
2019-02-05 13:04     ` Robin Murphy
2019-02-05 13:04       ` Robin Murphy
2019-02-05  9:25 ` [PATCH 0/5] Fix Arm system PMU hotplug issues Mark Rutland
2019-02-05  9:25   ` Mark Rutland

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