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Date:   Mon, 23 Oct 2023 09:48:09 +0100
From:   "Russell King (Oracle)" <linux@armlinux.org.uk>
To:     Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc:     James Morse <james.morse@arm.com>, linux-pm@vger.kernel.org,
        loongarch@lists.linux.dev, linux-acpi@vger.kernel.org,
        linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-riscv@lists.infradead.org, kvmarm@lists.linux.dev,
        x86@kernel.org, Salil Mehta <salil.mehta@huawei.com>,
        Jean-Philippe Brucker <jean-philippe@linaro.org>,
        jianyong.wu@arm.com, justin.he@arm.com
Subject: Re: [RFC PATCH v2 25/35] LoongArch: Use the __weak version of
 arch_unregister_cpu()
Message-ID: <ZTYzSQw0iLlAKNCn@shell.armlinux.org.uk>
References: <20230913163823.7880-1-james.morse@arm.com>
 <20230913163823.7880-26-james.morse@arm.com>
 <20230914154111.0000189d@Huawei.com>
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Sender: Russell King (Oracle) <linux@armlinux.org.uk>
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On Thu, Sep 14, 2023 at 03:41:11PM +0100, Jonathan Cameron wrote:
> On Wed, 13 Sep 2023 16:38:13 +0000
> James Morse <james.morse@arm.com> wrote:
> 
> > LoongArch provides its own arch_unregister_cpu(). This clears the
> > hotpluggable flag, then unregisters the CPU.
> > 
> > It isn't necessary to clear the hotpluggable flag when unregistering
> > a cpu. unregister_cpu() writes NULL to the percpu cpu_sys_devices
> > pointer, meaning cpu_is_hotpluggable() will return false, as
> > get_cpu_device() has returned NULL.
> 
> Thought that looked odd earlier but didn't care enough to dig.
> Seem unlikely state would persist for an unregistered cpu.
> Great to see confirmation.

Would it make sense to move this immedaitely after "LoongArch: Switch
over to GENERIC_CPU_DEVICES" ?

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