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Subject: Re: [PATCH v7 08/16] ACPI: Add post_eject to struct acpi_scan_handler
 for cpu hotplug
To: Jonathan Cameron <Jonathan.Cameron@huawei.com>, Thomas Gleixner
	<tglx@linutronix.de>, Peter Zijlstra <peterz@infradead.org>,
	<linux-pm@vger.kernel.org>, <loongarch@lists.linux.dev>,
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	<kvmarm@lists.linux.dev>, <x86@kernel.org>, Russell King
	<linux@armlinux.org.uk>, "Rafael J . Wysocki" <rafael@kernel.org>, Miguel
 Luis <miguel.luis@oracle.com>, James Morse <james.morse@arm.com>, Salil Mehta
	<salil.mehta@huawei.com>, Jean-Philippe Brucker <jean-philippe@linaro.org>,
	Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>
CC: Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>, Dave
 Hansen <dave.hansen@linux.intel.com>, <linuxarm@huawei.com>,
	<justin.he@arm.com>, <jianyong.wu@arm.com>
References: <20240418135412.14730-1-Jonathan.Cameron@huawei.com>
 <20240418135412.14730-9-Jonathan.Cameron@huawei.com>
From: Hanjun Guo <guohanjun@huawei.com>
Message-ID: <df2388a1-45d8-c42e-fca0-0e21f1810a9d@huawei.com>
Date: Tue, 23 Apr 2024 20:06:48 +0800
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On 2024/4/18 21:54, Jonathan Cameron wrote:
> From: James Morse <james.morse@arm.com>
> 
> struct acpi_scan_handler has a detach callback that is used to remove
> a driver when a bus is changed. When interacting with an eject-request,
> the detach callback is called before _EJ0.
> 
> This means the ACPI processor driver can't use _STA to determine if a
> CPU has been made not-present, or some of the other _STA bits have been
> changed. acpi_processor_remove() needs to know the value of _STA after
> _EJ0 has been called.
> 
> Add a post_eject callback to struct acpi_scan_handler. This is called
> after acpi_scan_hot_remove() has successfully called _EJ0. Because
> acpi_scan_check_and_detach() also clears the handler pointer,
> it needs to be told if the caller will go on to call
> acpi_bus_post_eject(), so that acpi_device_clear_enumerated()
> and clearing the handler pointer can be deferred.
> An extra flag is added to flags field introduced in the previous
> patch to achieve this.
> 
> Signed-off-by: James Morse <james.morse@arm.com>
> Reviewed-by: Joanthan Cameron <Jonathan.Cameron@huawei.com>
> Reviewed-by: Gavin Shan <gshan@redhat.com>
> Tested-by: Miguel Luis <miguel.luis@oracle.com>
> Tested-by: Vishnu Pajjuri <vishnu@os.amperecomputing.com>
> Tested-by: Jianyong Wu <jianyong.wu@arm.com>
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Reviewed-by: Hanjun Guo <guohanjun@huawei.com>