[PATCH v2 5/8] drm/amdgpu: Refactor sysfs removal

[Andrey Grodzovsky]

On 11/11/20 10:34 AM, Greg KH wrote:
> On Wed, Nov 11, 2020 at 10:13:13AM -0500, Andrey Grodzovsky wrote:
>> On 11/10/20 12:59 PM, Greg KH wrote:
>>> On Tue, Nov 10, 2020 at 12:54:21PM -0500, Andrey Grodzovsky wrote:
>>>> Hi, back to this after a long context switch for some higher priority stuff.
>>>>
>>>> So here I was able eventually to drop all this code and this change here https://nam11.safelinks.protection.outlook.com/?url=https:%2F%2Fcgit.freedesktop.org%2F~agrodzov%2Flinux%2Fcommit%2F%3Fh%3Damd-staging-drm-next-device-unplug%26id%3D61852c8a59b4dd89d637693552c73175b9f2ccd6&data=04%7C01%7CAndrey.Grodzovsky%40amd.com%7C9fbfecac94a340dfb68408d886571609%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637407055896651058%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=Ye8HJR1vidppcOBnlOgVu5GwKD2%2Bb5ztHbiI%2BubKKT0%3D&reserved=0
>>>> was enough for me. Seems like while device_remove_file can handle the use
>>>> case where the file and the parent directory already gone,
>>>> sysfs_remove_group goes down in flames in that case
>>>> due to kobj->sd being unset on device removal.
>>> A driver shouldn't ever have to remove individual sysfs groups, the
>>> driver core/bus logic should do it for them automatically.
>>>
>>> And whenever a driver calls a sysfs_* call, that's a hint that something
>>> is not working properly.
>>
>>
>> Do you mean that while the driver creates the groups and files explicitly
>> from it's different subsystems it should not explicitly remove each
>> one of them because all of them should be removed at once (and
>> recursively) when the device is being removed ?
> Individual drivers should never add groups/files in sysfs, the driver
> core should do it properly for you if you have everything set up
> properly.  And yes, the driver core will automatically remove them as
> well.
>
> Please use the default groups attribute for your bus/subsystem and this
> will happen automagically.


Hi Greg, I tried your suggestion to hang amdgpu's sysfs
attributes on default attributes in struct device.groups but turns out it's not 
usable since by the
time i have access to struct device from amdgpu code it has already been 
initialized by pci core
(i.e.  past the point where device_add->device_add_attrs->device_add_groups with 
dev->groups is called)
and so i can't really use it.

What I can only think of using is creating my own struct attribute_group ** 
array in amdgpu where I aggregate all
amdgpu sysfs attributes, call device_add_groups in the end of amgpu pci probe 
with that array and on device remove call
device_remove_groups with the same array.

Do you maybe have a better suggestion for me ?

Andrey


>
> thanks,
>
> greg k-h
>