[PATCH AUTOSEL 6.7 15/18] platform/x86: wmi: Remove ACPI handlers after WMI devices

[PATCH AUTOSEL 6.7 15/18] platform/x86: wmi: Remove ACPI handlers after WMI devices

[Sasha Levin]

From: Armin Wolf <W_Armin@gmx.de>

[ Upstream commit 22574e17626391ad969af9a13aaa58a1b37ad384 ]

When removing the ACPI notify/address space handlers, the WMI devices
are still active and might still depend on ACPI EC access or
WMI events.
Fix this by removing the ACPI handlers after all WMI devices
associated with an ACPI device have been removed.

Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Link: https://lore.kernel.org/r/20231218192420.305411-3-W_Armin@gmx.de
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/platform/x86/wmi.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi.c
index 5dd22258cb3b..d400e61d6801 100644
--- a/drivers/platform/x86/wmi.c
+++ b/drivers/platform/x86/wmi.c
@@ -1494,13 +1494,12 @@ static void acpi_wmi_remove(struct platform_device *device)
 	struct acpi_device *acpi_device = ACPI_COMPANION(&device->dev);
 	struct device *wmi_bus_device = dev_get_drvdata(&device->dev);
 
-	acpi_remove_notify_handler(acpi_device->handle, ACPI_ALL_NOTIFY,
-				   acpi_wmi_notify_handler);
-	acpi_remove_address_space_handler(acpi_device->handle,
-				ACPI_ADR_SPACE_EC, &acpi_wmi_ec_space_handler);
-
 	device_for_each_child_reverse(wmi_bus_device, NULL, wmi_remove_device);
 	device_unregister(wmi_bus_device);
+
+	acpi_remove_notify_handler(acpi_device->handle, ACPI_ALL_NOTIFY, acpi_wmi_notify_handler);
+	acpi_remove_address_space_handler(acpi_device->handle, ACPI_ADR_SPACE_EC,
+					  &acpi_wmi_ec_space_handler);
 }
 
 static int acpi_wmi_probe(struct platform_device *device)
-- 
2.43.0

Re: [PATCH AUTOSEL 6.7 15/18] platform/x86: wmi: Remove ACPI handlers after WMI devices

[Armin Wolf]

Am 16.01.24 um 01:12 schrieb Sasha Levin:

> From: Armin Wolf <W_Armin@gmx.de>
>
> [ Upstream commit 22574e17626391ad969af9a13aaa58a1b37ad384 ]
>
> When removing the ACPI notify/address space handlers, the WMI devices
> are still active and might still depend on ACPI EC access or
> WMI events.
> Fix this by removing the ACPI handlers after all WMI devices
> associated with an ACPI device have been removed.

Hello,

i would advise against including this patch in the next stable kernels.

The WMI ACPI notify handler is still using list_for_each_entry() which is
not safe when the WMI devices are removed before the ACPI notify handler.

This issue existed inside the WMI code for a long time, but this patch might
trigger it. Since no users reported any issues regarding ACPI errors during
WMI removal, i would drop this patch.

Thanks,
Armin Wolf

> Reviewed-by: Hans de Goede <hdegoede@redhat.com>
> Signed-off-by: Armin Wolf <W_Armin@gmx.de>
> Link: https://lore.kernel.org/r/20231218192420.305411-3-W_Armin@gmx.de
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> Signed-off-by: Sasha Levin <sashal@kernel.org>
> ---
>   drivers/platform/x86/wmi.c | 9 ++++-----
>   1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi.c
> index 5dd22258cb3b..d400e61d6801 100644
> --- a/drivers/platform/x86/wmi.c
> +++ b/drivers/platform/x86/wmi.c
> @@ -1494,13 +1494,12 @@ static void acpi_wmi_remove(struct platform_device *device)
>   	struct acpi_device *acpi_device = ACPI_COMPANION(&device->dev);
>   	struct device *wmi_bus_device = dev_get_drvdata(&device->dev);
>
> -	acpi_remove_notify_handler(acpi_device->handle, ACPI_ALL_NOTIFY,
> -				   acpi_wmi_notify_handler);
> -	acpi_remove_address_space_handler(acpi_device->handle,
> -				ACPI_ADR_SPACE_EC, &acpi_wmi_ec_space_handler);
> -
>   	device_for_each_child_reverse(wmi_bus_device, NULL, wmi_remove_device);
>   	device_unregister(wmi_bus_device);
> +
> +	acpi_remove_notify_handler(acpi_device->handle, ACPI_ALL_NOTIFY, acpi_wmi_notify_handler);
> +	acpi_remove_address_space_handler(acpi_device->handle, ACPI_ADR_SPACE_EC,
> +					  &acpi_wmi_ec_space_handler);
>   }
>
>   static int acpi_wmi_probe(struct platform_device *device)

Re: [PATCH AUTOSEL 6.7 15/18] platform/x86: wmi: Remove ACPI handlers after WMI devices

[Sasha Levin]

On Tue, Jan 16, 2024 at 12:53:46PM +0100, Armin Wolf wrote:
>Am 16.01.24 um 01:12 schrieb Sasha Levin:
>
>>From: Armin Wolf <W_Armin@gmx.de>
>>
>>[ Upstream commit 22574e17626391ad969af9a13aaa58a1b37ad384 ]
>>
>>When removing the ACPI notify/address space handlers, the WMI devices
>>are still active and might still depend on ACPI EC access or
>>WMI events.
>>Fix this by removing the ACPI handlers after all WMI devices
>>associated with an ACPI device have been removed.
>
>Hello,
>
>i would advise against including this patch in the next stable kernels.
>
>The WMI ACPI notify handler is still using list_for_each_entry() which is
>not safe when the WMI devices are removed before the ACPI notify handler.
>
>This issue existed inside the WMI code for a long time, but this patch might
>trigger it. Since no users reported any issues regarding ACPI errors during
>WMI removal, i would drop this patch.

Ack, I'll drop it.

-- 
Thanks,
Sasha