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Message-ID: <CAJZ5v0jmbxc=WMtx+d_sdwUtS+KUgabqgW-q_Au19fzDV-yrQQ@mail.gmail.com>
Date: Mon, 22 Apr 2024 21:10:12 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Jonathan Cameron <Jonathan.Cameron@...wei.com>
Cc: Thomas Gleixner <tglx@...utronix.de>, Peter Zijlstra <peterz@...radead.org>, linux-pm@...r.kernel.org,
loongarch@...ts.linux.dev, linux-acpi@...r.kernel.org,
linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev, x86@...nel.org,
Russell King <linux@...linux.org.uk>, "Rafael J . Wysocki" <rafael@...nel.org>,
Miguel Luis <miguel.luis@...cle.com>, James Morse <james.morse@....com>,
Salil Mehta <salil.mehta@...wei.com>, Jean-Philippe Brucker <jean-philippe@...aro.org>,
Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>, linuxarm@...wei.com, justin.he@....com,
jianyong.wu@....com
Subject: Re: [PATCH v7 08/16] ACPI: Add post_eject to struct acpi_scan_handler
for cpu hotplug
On Thu, Apr 18, 2024 at 3:58 PM Jonathan Cameron
<Jonathan.Cameron@...wei.com> wrote:
>
> From: James Morse <james.morse@....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@....com>
> Reviewed-by: Joanthan Cameron <Jonathan.Cameron@...wei.com>
> Reviewed-by: Gavin Shan <gshan@...hat.com>
> Tested-by: Miguel Luis <miguel.luis@...cle.com>
> Tested-by: Vishnu Pajjuri <vishnu@...amperecomputing.com>
> Tested-by: Jianyong Wu <jianyong.wu@....com>
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
No objections:
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ----
> v7:
> - No change.
> v6:
> - Switch to flags.
> Russell, you hadn't signed off on this when posting last time.
> Do you want to insert a suitable tag now?
> v5:
> - Rebase to take into account the changes to scan handling in the
> meantime.
> ---
> drivers/acpi/acpi_processor.c | 4 ++--
> drivers/acpi/scan.c | 30 +++++++++++++++++++++++++++---
> include/acpi/acpi_bus.h | 1 +
> 3 files changed, 30 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
> index 4e65011e706c..beb1761db579 100644
> --- a/drivers/acpi/acpi_processor.c
> +++ b/drivers/acpi/acpi_processor.c
> @@ -471,7 +471,7 @@ static int acpi_processor_add(struct acpi_device *device,
>
> #ifdef CONFIG_ACPI_HOTPLUG_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;
>
> @@ -639,7 +639,7 @@ static struct acpi_scan_handler processor_handler = {
> .ids = processor_device_ids,
> .attach = acpi_processor_add,
> #ifdef CONFIG_ACPI_HOTPLUG_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 1ec9677e6c2d..3ec54624664a 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -245,6 +245,7 @@ static int acpi_scan_try_to_offline(struct acpi_device *device)
> }
>
> #define ACPI_SCAN_CHECK_FLAG_STATUS BIT(0)
> +#define ACPI_SCAN_CHECK_FLAG_EJECT BIT(1)
>
> static int acpi_scan_check_and_detach(struct acpi_device *adev, void *p)
> {
> @@ -273,8 +274,6 @@ static int acpi_scan_check_and_detach(struct acpi_device *adev, void *p)
> if (handler) {
> if (handler->detach)
> handler->detach(adev);
> -
> - adev->handler = NULL;
> } else {
> device_release_driver(&adev->dev);
> }
> @@ -284,6 +283,28 @@ static int acpi_scan_check_and_detach(struct acpi_device *adev, void *p)
> */
> acpi_device_set_power(adev, ACPI_STATE_D3_COLD);
> adev->flags.initialized = false;
> +
> + /* For eject this is deferred to acpi_bus_post_eject() */
> + if (!(flags & ACPI_SCAN_CHECK_FLAG_EJECT)) {
> + adev->handler = NULL;
> + acpi_device_clear_enumerated(adev);
> + }
> + return 0;
> +}
> +
> +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;
> @@ -301,6 +322,7 @@ static int acpi_scan_hot_remove(struct acpi_device *device)
> acpi_handle handle = device->handle;
> unsigned long long sta;
> acpi_status status;
> + uintptr_t flags = ACPI_SCAN_CHECK_FLAG_EJECT;
>
> if (device->handler && device->handler->hotplug.demand_offline) {
> if (!acpi_scan_is_offline(device, true))
> @@ -313,7 +335,7 @@ static int acpi_scan_hot_remove(struct acpi_device *device)
>
> acpi_handle_debug(handle, "Ejecting\n");
>
> - acpi_bus_trim(device);
> + acpi_scan_check_and_detach(device, (void *)flags);
>
> acpi_evaluate_lck(handle, 0);
> /*
> @@ -336,6 +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 e7796f373d0d..51a4b936f19e 100644
> --- a/include/acpi/acpi_bus.h
> +++ b/include/acpi/acpi_bus.h
> @@ -129,6 +129,7 @@ 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;
> --
> 2.39.2
>
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