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([2001:8003:e5b0:9f00:dbbc:1945:6e65:ec5]) by smtp.gmail.com with ESMTPSA id f93-20020a17090a706600b0026fa1931f66sm8310527pjk.9.2023.09.18.17.31.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 18 Sep 2023 17:31:25 -0700 (PDT) Message-ID: Date: Tue, 19 Sep 2023 10:31:17 +1000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.12.0 Subject: Re: [RFC PATCH v2 21/35] ACPI: Add post_eject to struct acpi_scan_handler for cpu hotplug Content-Language: en-US To: James Morse , 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 Cc: x86@kernel.org, Salil Mehta , Russell King , Jean-Philippe Brucker , jianyong.wu@arm.com, justin.he@arm.com References: <20230913163823.7880-1-james.morse@arm.com> <20230913163823.7880-22-james.morse@arm.com> From: Gavin Shan In-Reply-To: <20230913163823.7880-22-james.morse@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On 9/14/23 02:38, James Morse wrote: > 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. > It's helpful to mention which ACPI processor driver needs to use _STA to determine the status here. I guess the ACPI processor driver will behave differently depending on the status. > Add a post_eject callback to struct acpi_scan_handler. This is called > after acpi_scan_hot_remove() has successfully called _EJ0. Because > acpi_bus_trim_one() 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. The existing not-used pointer is used for this. > > Signed-off-by: James Morse > --- > drivers/acpi/acpi_processor.c | 4 +-- > drivers/acpi/scan.c | 52 ++++++++++++++++++++++++++++++----- > include/acpi/acpi_bus.h | 1 + > 3 files changed, 48 insertions(+), 9 deletions(-) > Reviewed-by: Gavin Shan > diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c > index 22a15a614f95..00dcc23d49a8 100644 > --- a/drivers/acpi/acpi_processor.c > +++ b/drivers/acpi/acpi_processor.c > @@ -459,7 +459,7 @@ static int acpi_processor_add(struct acpi_device *device, > > #ifdef CONFIG_ACPI_HOTPLUG_PRESENT_CPU > /* Removal */ > -static void acpi_processor_remove(struct acpi_device *device) > +static void acpi_processor_post_eject(struct acpi_device *device) > { > struct acpi_processor *pr; > > @@ -627,7 +627,7 @@ static struct acpi_scan_handler processor_handler = { > .ids = processor_device_ids, > .attach = acpi_processor_add, > #ifdef CONFIG_ACPI_HOTPLUG_PRESENT_CPU > - .detach = acpi_processor_remove, > + .post_eject = acpi_processor_post_eject, > #endif > .hotplug = { > .enabled = true, > diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c > index a675333618ae..b6d2f01640a9 100644 > --- a/drivers/acpi/scan.c > +++ b/drivers/acpi/scan.c > @@ -244,18 +244,28 @@ static int acpi_scan_try_to_offline(struct acpi_device *device) > return 0; > } > > -static int acpi_bus_trim_one(struct acpi_device *adev, void *not_used) > +/** > + * acpi_bus_trim_one() - Detach scan handlers and drivers from ACPI device > + * objects. > + * @adev: Root of the ACPI namespace scope to walk. > + * @eject: Pointer to a bool that indicates if this was due to an > + * eject-request. > + * > + * Must be called under acpi_scan_lock. > + * If @eject points to true, clearing the device enumeration is deferred until > + * acpi_bus_post_eject() is called. > + */ > +static int acpi_bus_trim_one(struct acpi_device *adev, void *eject) > { > struct acpi_scan_handler *handler = adev->handler; > + bool is_eject = *(bool *)eject; > > - acpi_dev_for_each_child_reverse(adev, acpi_bus_trim_one, NULL); > + acpi_dev_for_each_child_reverse(adev, acpi_bus_trim_one, eject); > > adev->flags.match_driver = false; > if (handler) { > if (handler->detach) > handler->detach(adev); > - > - adev->handler = NULL; > } else { > device_release_driver(&adev->dev); > } > @@ -265,7 +275,12 @@ static int acpi_bus_trim_one(struct acpi_device *adev, void *not_used) > */ > acpi_device_set_power(adev, ACPI_STATE_D3_COLD); > adev->flags.initialized = false; > - acpi_device_clear_enumerated(adev); > + > + /* For eject this is deferred to acpi_bus_post_eject() */ > + if (!is_eject) { > + adev->handler = NULL; > + acpi_device_clear_enumerated(adev); > + } > > return 0; > } > @@ -278,15 +293,36 @@ static int acpi_bus_trim_one(struct acpi_device *adev, void *not_used) > */ > void acpi_bus_trim(struct acpi_device *adev) > { > - acpi_bus_trim_one(adev, NULL); > + bool eject = false; > + > + acpi_bus_trim_one(adev, &eject); > } > EXPORT_SYMBOL_GPL(acpi_bus_trim); > > +static int acpi_bus_post_eject(struct acpi_device *adev, void *not_used) > +{ > + struct acpi_scan_handler *handler = adev->handler; > + > + acpi_dev_for_each_child_reverse(adev, acpi_bus_post_eject, NULL); > + > + if (handler) { > + if (handler->post_eject) > + handler->post_eject(adev); > + > + adev->handler = NULL; > + } > + > + acpi_device_clear_enumerated(adev); > + > + return 0; > +} > + > static int acpi_scan_hot_remove(struct acpi_device *device) > { > acpi_handle handle = device->handle; > unsigned long long sta; > acpi_status status; > + bool eject = true; > > if (device->handler && device->handler->hotplug.demand_offline) { > if (!acpi_scan_is_offline(device, true)) > @@ -299,7 +335,7 @@ static int acpi_scan_hot_remove(struct acpi_device *device) > > acpi_handle_debug(handle, "Ejecting\n"); > > - acpi_bus_trim(device); > + acpi_bus_trim_one(device, &eject); > > acpi_evaluate_lck(handle, 0); > /* > @@ -322,6 +358,8 @@ static int acpi_scan_hot_remove(struct acpi_device *device) > } else if (sta & ACPI_STA_DEVICE_ENABLED) { > acpi_handle_warn(handle, > "Eject incomplete - status 0x%llx\n", sta); > + } else { > + acpi_bus_post_eject(device, NULL); > } > > return 0; > diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h > index 254685085c82..1b7e1acf925b 100644 > --- a/include/acpi/acpi_bus.h > +++ b/include/acpi/acpi_bus.h > @@ -127,6 +127,7 @@ struct acpi_scan_handler { > bool (*match)(const char *idstr, const struct acpi_device_id **matchid); > int (*attach)(struct acpi_device *dev, const struct acpi_device_id *id); > void (*detach)(struct acpi_device *dev); > + void (*post_eject)(struct acpi_device *dev); > void (*bind)(struct device *phys_dev); > void (*unbind)(struct device *phys_dev); > struct acpi_hotplug_profile hotplug; Thanks, Gavin