[PATCH 1/6] drm/sysfs: Remove version attribute

[Dmitry Baryshkov]

On October 1, 2024 2:07:28 PM GMT+03:00, Heiner Kallweit <hkallweit1 at gmail.com> wrote:
>On 01.10.2024 12:01, Dmitry Baryshkov wrote:
>> On September 30, 2024 1:49:41 PM GMT+03:00, Heiner Kallweit <hkallweit1 at gmail.com> wrote:
>>> On 22.09.2024 16:55, Dmitry Baryshkov wrote:
>>>> On Sun, Sep 08, 2024 at 02:08:58PM GMT, Heiner Kallweit wrote:
>>>>> This undocumented attribute returns a version string which hasn't been
>>>>> changed for ages. libdrm doesn't use it and I also found no other user.
>>>>> So I think we can remove it.
>>>>
>>>> This file is a part of the ABI. Commit 82d5e73f6b79 ("drm: drop obsolete
>>>> drm_core.h") replaced variable string with the fixed value that we
>>>> currently have, but at the same it clearly documented that the file is
>>>> being preserved for the sake of binary compatibility.
>>>>
>>> The drm version attribute is documented neither under Documentation/gpu
>>> nor under Documentation/ABI. So do we really have to consider it
>>> part of the ABI? And are you aware of any actual user of this attribute?
>>>
>>> The author of 82d5e73f6b79 wasn't sure either, and therefore didn't
>>> dare to drop the attribute (8 yrs ago). He didn't make any statement that
>>> the attribute is actually used.
>> 
>> A very quick search points out that the file is being used: 
>> 
>> <https://codesearch.debian.net/search?q=drm%2Fversion>
>> 
>
>Thanks. However this script doesn't actually use the version value
>and would work perfectly fine also w/o this attribute.
>
>> 
>>>
>>> 6.12-rc1 is just out, so we could drop the attribute in linux-next and
>>> would have several weeks before the next merge window to find out
>>> whether anybody complains.
>> 
>> No, this is not the way to treat userspace ABI.
>> 
>
>Mileage of subsystem maintainers seems to vary in this regard.
>See following example where Greg supported such an approach.
>https://www.spinics.net/lists/linux-i2c/msg71821.html
>But fine with me, we can also leave the version attribute in.

Let's leave the final decision to subsystem maintainers.


>
>>>
>>>>>
>>>>> Signed-off-by: Heiner Kallweit <hkallweit1 at gmail.com>
>>>>> ---
>>>>>  drivers/gpu/drm/drm_sysfs.c | 12 ------------
>>>>>  1 file changed, 12 deletions(-)
>>>>>
>>>>> diff --git a/drivers/gpu/drm/drm_sysfs.c b/drivers/gpu/drm/drm_sysfs.c
>>>>> index fb3bbb6ad..49e5faf11 100644
>>>>> --- a/drivers/gpu/drm/drm_sysfs.c
>>>>> +++ b/drivers/gpu/drm/drm_sysfs.c
>>>>> @@ -126,8 +126,6 @@ static const struct component_ops typec_connector_ops = {
>>>>>  	.unbind = typec_connector_unbind,
>>>>>  };
>>>>>  
>>>>> -static CLASS_ATTR_STRING(version, S_IRUGO, "drm 1.1.0 20060810");
>>>>> -
>>>>>  /**
>>>>>   * drm_sysfs_init - initialize sysfs helpers
>>>>>   *
>>>>> @@ -140,19 +138,10 @@ static CLASS_ATTR_STRING(version, S_IRUGO, "drm 1.1.0 20060810");
>>>>>   */
>>>>>  int drm_sysfs_init(void)
>>>>>  {
>>>>> -	int err;
>>>>> -
>>>>>  	drm_class = class_create("drm");
>>>>>  	if (IS_ERR(drm_class))
>>>>>  		return PTR_ERR(drm_class);
>>>>>  
>>>>> -	err = class_create_file(drm_class, &class_attr_version.attr);
>>>>> -	if (err) {
>>>>> -		class_destroy(drm_class);
>>>>> -		drm_class = NULL;
>>>>> -		return err;
>>>>> -	}
>>>>> -
>>>>>  	drm_class->devnode = drm_devnode;
>>>>>  
>>>>>  	drm_sysfs_acpi_register();
>>>>> @@ -169,7 +158,6 @@ void drm_sysfs_destroy(void)
>>>>>  	if (IS_ERR_OR_NULL(drm_class))
>>>>>  		return;
>>>>>  	drm_sysfs_acpi_unregister();
>>>>> -	class_remove_file(drm_class, &class_attr_version.attr);
>>>>>  	class_destroy(drm_class);
>>>>>  	drm_class = NULL;
>>>>>  }
>>>>> -- 
>>>>> 2.46.0
>>>>>
>>>>>
>>>>
>>>
>> 
>> 
>


-- 
With best wishes
Dmitry