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Date: Mon, 4 Aug 2025 09:22:26 +0100
From: Leo Yan <leo.yan@arm.com>
To: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>,
	Mike Leach <mike.leach@linaro.org>,
	James Clark <james.clark@linaro.org>,
	Levi Yun <yeoreum.yun@arm.com>,
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	coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 01/28] coresight: Change device mode to atomic type
Message-ID: <20250804082226.GH143191@e132581.arm.com>
References: <20250701-arm_cs_pm_fix_v3-v2-0-23ebb864fcc1@arm.com>
 <20250701-arm_cs_pm_fix_v3-v2-1-23ebb864fcc1@arm.com>
 <cd8cba00-b495-4aab-b63c-699bb2c12d48@arm.com>
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In-Reply-To: <cd8cba00-b495-4aab-b63c-699bb2c12d48@arm.com>

On Tue, Jul 15, 2025 at 12:23:22PM +0530, Anshuman Khandual wrote:
> On 01/07/25 8:23 PM, Leo Yan wrote:
> > The device mode is defined as local type. This type cannot promise
> > SMP-safe access.
> > 
> > Change to atomic type and impose relax ordering, which ensures the
> > SMP-safe synchronisation and the ordering between the mode setting and
> > relevant operations.
> 
> 
> But have we really faced such problems on real systems due to local_t
> or this is just an improvement ?

This is an improvement based on reading code. The reason is the
variable is accessed by mutliple CPUs but not per-CPU access.

Thanks,
Leo