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Message-ID: <a8602a4a-39e1-46c3-9fe9-b6896c75fa73@gmx.de>
Date: Tue, 27 Feb 2024 23:47:11 +0100
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Subject: Re: [PATCH 2/3] platform/x86: wmi: Do not instantiate older WMI
 drivers multiple times
To: =?UTF-8?Q?Pali_Roh=C3=A1r?= <pali@kernel.org>
Cc: jithu.joseph@intel.com, linux@weissschuh.net, hdegoede@redhat.com,
 ilpo.jarvinen@linux.intel.com, Dell.Client.Kernel@dell.com,
 jdelvare@suse.com, linux@roeck-us.net, platform-driver-x86@vger.kernel.org,
 linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20240226193557.2888-1-W_Armin@gmx.de>
 <20240226193557.2888-2-W_Armin@gmx.de> <20240227203058.eun4ylvhk4t7uogk@pali>
Content-Language: en-US
From: Armin Wolf <W_Armin@gmx.de>
In-Reply-To: <20240227203058.eun4ylvhk4t7uogk@pali>
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Am 27.02.24 um 21:30 schrieb Pali Roh=C3=A1r:

> On Monday 26 February 2024 20:35:56 Armin Wolf wrote:
>> Many older WMI drivers cannot be instantiated multiple times for
>> two reasons:
>>
>> - they are using the legacy GUID-based WMI API
>> - they are singletons (with global state)
>>
>> Prevent such WMI drivers from binding to WMI devices with a duplicated
>> GUID, as this would mean that the WMI driver will be instantiated at
>> least two times (one for the original GUID and one for the duplicated
>> GUID).
>> WMI drivers which can be instantiated multiple times can signal this
>> by setting a flag inside struct wmi_driver.
> What do you think about opposite direction? Adding ".singleton =3D true"
> into every driver which is not compatible with duplicated initialization
> and having the default value that drivers are not singletons.
>
> But if the direction it to not accept new "legacy" drivers and start get
> rid of all "legacy" drivers by rewriting them, then it does not matter
> if "no_singleton" or "is_singleton" is used...

Hi,

i want to make sure that i wont forget any legacy WMI drivers. This way, t=
he
older legacy WMI drivers automatically initialize no_singleton with false.

Also i intent to not accept new legacy WMI drivers.

Thanks,
Armin Wolf

>> Tested on a ASUS Prime B650-Plus.
>>
>> Signed-off-by: Armin Wolf <W_Armin@gmx.de>
>> ---
>>   drivers/hwmon/dell-smm-hwmon.c                 |  1 +
>>   drivers/platform/x86/dell/dell-wmi-ddv.c       |  1 +
>>   drivers/platform/x86/intel/wmi/sbl-fw-update.c |  1 +
>>   drivers/platform/x86/intel/wmi/thunderbolt.c   |  1 +
>>   drivers/platform/x86/wmi-bmof.c                |  1 +
>>   drivers/platform/x86/wmi.c                     | 12 ++++++++++++
>>   include/linux/wmi.h                            |  2 ++
>>   7 files changed, 19 insertions(+)
>>
>> diff --git a/drivers/hwmon/dell-smm-hwmon.c b/drivers/hwmon/dell-smm-hw=
mon.c
>> index 6d8c0f328b7b..168d669c4eca 100644
>> --- a/drivers/hwmon/dell-smm-hwmon.c
>> +++ b/drivers/hwmon/dell-smm-hwmon.c
>> @@ -1587,6 +1587,7 @@ static struct wmi_driver dell_smm_wmi_driver =3D =
{
>>   	},
>>   	.id_table =3D dell_smm_wmi_id_table,
>>   	.probe =3D dell_smm_wmi_probe,
>> +	.no_singleton =3D true,
>>   };
>>
>>   /*
>> diff --git a/drivers/platform/x86/dell/dell-wmi-ddv.c b/drivers/platfor=
m/x86/dell/dell-wmi-ddv.c
>> index db1e9240dd02..0b2299f7a2de 100644
>> --- a/drivers/platform/x86/dell/dell-wmi-ddv.c
>> +++ b/drivers/platform/x86/dell/dell-wmi-ddv.c
>> @@ -882,6 +882,7 @@ static struct wmi_driver dell_wmi_ddv_driver =3D {
>>   	},
>>   	.id_table =3D dell_wmi_ddv_id_table,
>>   	.probe =3D dell_wmi_ddv_probe,
>> +	.no_singleton =3D true,
>>   };
>>   module_wmi_driver(dell_wmi_ddv_driver);
>>
>> diff --git a/drivers/platform/x86/intel/wmi/sbl-fw-update.c b/drivers/p=
latform/x86/intel/wmi/sbl-fw-update.c
>> index 040153ad67c1..75c82c08117f 100644
>> --- a/drivers/platform/x86/intel/wmi/sbl-fw-update.c
>> +++ b/drivers/platform/x86/intel/wmi/sbl-fw-update.c
>> @@ -131,6 +131,7 @@ static struct wmi_driver intel_wmi_sbl_fw_update_dr=
iver =3D {
>>   	.probe =3D intel_wmi_sbl_fw_update_probe,
>>   	.remove =3D intel_wmi_sbl_fw_update_remove,
>>   	.id_table =3D intel_wmi_sbl_id_table,
>> +	.no_singleton =3D true,
>>   };
>>   module_wmi_driver(intel_wmi_sbl_fw_update_driver);
>>
>> diff --git a/drivers/platform/x86/intel/wmi/thunderbolt.c b/drivers/pla=
tform/x86/intel/wmi/thunderbolt.c
>> index e2ad3f46f356..08df560a2c7a 100644
>> --- a/drivers/platform/x86/intel/wmi/thunderbolt.c
>> +++ b/drivers/platform/x86/intel/wmi/thunderbolt.c
>> @@ -63,6 +63,7 @@ static struct wmi_driver intel_wmi_thunderbolt_driver=
 =3D {
>>   		.dev_groups =3D tbt_groups,
>>   	},
>>   	.id_table =3D intel_wmi_thunderbolt_id_table,
>> +	.no_singleton =3D true,
>>   };
>>
>>   module_wmi_driver(intel_wmi_thunderbolt_driver);
>> diff --git a/drivers/platform/x86/wmi-bmof.c b/drivers/platform/x86/wmi=
-bmof.c
>> index 644d2fd889c0..df6f0ae6e6c7 100644
>> --- a/drivers/platform/x86/wmi-bmof.c
>> +++ b/drivers/platform/x86/wmi-bmof.c
>> @@ -94,6 +94,7 @@ static struct wmi_driver wmi_bmof_driver =3D {
>>   	.probe =3D wmi_bmof_probe,
>>   	.remove =3D wmi_bmof_remove,
>>   	.id_table =3D wmi_bmof_id_table,
>> +	.no_singleton =3D true,
>>   };
>>
>>   module_wmi_driver(wmi_bmof_driver);
>> diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi.c
>> index 29dfe52eb802..349deced87e8 100644
>> --- a/drivers/platform/x86/wmi.c
>> +++ b/drivers/platform/x86/wmi.c
>> @@ -883,6 +883,18 @@ static int wmi_dev_probe(struct device *dev)
>>   	struct wmi_driver *wdriver =3D drv_to_wdrv(dev->driver);
>>   	int ret =3D 0;
>>
>> +	/* Some older WMI drivers will break if instantiated multiple times,
>> +	 * so they are blocked from probing WMI devices with a duplicated GUI=
D.
>> +	 *
>> +	 * New WMI drivers should support being instantiated multiple times.
>> +	 */
>> +	if (test_bit(WMI_GUID_DUPLICATED, &wblock->flags) && !wdriver->no_sin=
gleton) {
>> +		dev_warn(dev, "Legacy driver %s cannot be instantiated multiple time=
s\n",
>> +			 dev->driver->name);
>> +
>> +		return -ENODEV;
>> +	}
>> +
>>   	if (wdriver->notify) {
>>   		if (test_bit(WMI_NO_EVENT_DATA, &wblock->flags) && !wdriver->no_not=
ify_data)
>>   			return -ENODEV;
>> diff --git a/include/linux/wmi.h b/include/linux/wmi.h
>> index 781958310bfb..63cca3b58d6d 100644
>> --- a/include/linux/wmi.h
>> +++ b/include/linux/wmi.h
>> @@ -49,6 +49,7 @@ u8 wmidev_instance_count(struct wmi_device *wdev);
>>    * @driver: Driver model structure
>>    * @id_table: List of WMI GUIDs supported by this driver
>>    * @no_notify_data: Driver supports WMI events which provide no event=
 data
>> + * @no_singleton: Driver can be instantiated multiple times
>>    * @probe: Callback for device binding
>>    * @remove: Callback for device unbinding
>>    * @notify: Callback for receiving WMI events
>> @@ -59,6 +60,7 @@ struct wmi_driver {
>>   	struct device_driver driver;
>>   	const struct wmi_device_id *id_table;
>>   	bool no_notify_data;
>> +	bool no_singleton;
>>
>>   	int (*probe)(struct wmi_device *wdev, const void *context);
>>   	void (*remove)(struct wmi_device *wdev);
>> --
>> 2.39.2
>>