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Message-ID: <807c658b-358f-47c3-b14a-f1b76e9208c6@redhat.com>
Date: Wed, 28 Feb 2024 14:23:47 +0100
From: Hans de Goede <hdegoede@...hat.com>
To: Armin Wolf <W_Armin@....de>, Pali Rohár <pali@...nel.org>
Cc: jithu.joseph@...el.com, linux@...ssschuh.net,
ilpo.jarvinen@...ux.intel.com, Dell.Client.Kernel@...l.com,
jdelvare@...e.com, linux@...ck-us.net, platform-driver-x86@...r.kernel.org,
linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] platform/x86: wmi: Do not instantiate older WMI
drivers multiple times
Hi Armin,
On 2/27/24 23:47, Armin Wolf wrote:
> Am 27.02.24 um 21:30 schrieb Pali Rohár:
>
>> 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 = 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, the
> older legacy WMI drivers automatically initialize no_singleton with false.
>
> Also i intent to not accept new legacy WMI drivers.
Somewhat offtopic question, how do you plan to handle the case where
there are 2 WMI GUIDs for what really is a single "thing",
specifically one main WMI GUID for a vendor specific interface
for say the embedded-controller and a separate GUID for events ?
IIRC we have several such cases. I thought we even have a case
where the main WMI GUID already is bound to using wmi_bus wmi_driver,
while the event guid is listened to by using wmi_install_notify_handler()
but I cannot find the code doing this, so I might be mistaken on this.
Regards,
Hans
>>> Tested on a ASUS Prime B650-Plus.
>>>
>>> Signed-off-by: Armin Wolf <W_Armin@....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-hwmon.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 = {
>>> },
>>> .id_table = dell_smm_wmi_id_table,
>>> .probe = dell_smm_wmi_probe,
>>> + .no_singleton = true,
>>> };
>>>
>>> /*
>>> diff --git a/drivers/platform/x86/dell/dell-wmi-ddv.c b/drivers/platform/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 = {
>>> },
>>> .id_table = dell_wmi_ddv_id_table,
>>> .probe = dell_wmi_ddv_probe,
>>> + .no_singleton = true,
>>> };
>>> module_wmi_driver(dell_wmi_ddv_driver);
>>>
>>> diff --git a/drivers/platform/x86/intel/wmi/sbl-fw-update.c b/drivers/platform/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_driver = {
>>> .probe = intel_wmi_sbl_fw_update_probe,
>>> .remove = intel_wmi_sbl_fw_update_remove,
>>> .id_table = intel_wmi_sbl_id_table,
>>> + .no_singleton = true,
>>> };
>>> module_wmi_driver(intel_wmi_sbl_fw_update_driver);
>>>
>>> diff --git a/drivers/platform/x86/intel/wmi/thunderbolt.c b/drivers/platform/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 = {
>>> .dev_groups = tbt_groups,
>>> },
>>> .id_table = intel_wmi_thunderbolt_id_table,
>>> + .no_singleton = 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 = {
>>> .probe = wmi_bmof_probe,
>>> .remove = wmi_bmof_remove,
>>> .id_table = wmi_bmof_id_table,
>>> + .no_singleton = 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 = drv_to_wdrv(dev->driver);
>>> int ret = 0;
>>>
>>> + /* Some older WMI drivers will break if instantiated multiple times,
>>> + * so they are blocked from probing WMI devices with a duplicated GUID.
>>> + *
>>> + * New WMI drivers should support being instantiated multiple times.
>>> + */
>>> + if (test_bit(WMI_GUID_DUPLICATED, &wblock->flags) && !wdriver->no_singleton) {
>>> + dev_warn(dev, "Legacy driver %s cannot be instantiated multiple times\n",
>>> + dev->driver->name);
>>> +
>>> + return -ENODEV;
>>> + }
>>> +
>>> if (wdriver->notify) {
>>> if (test_bit(WMI_NO_EVENT_DATA, &wblock->flags) && !wdriver->no_notify_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
>>>
>
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