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

From: Greg KH <gregkh@linuxfoundation.org>
To: Andrey Grodzovsky <Andrey.Grodzovsky@amd.com>
Cc: daniel.vetter@ffwll.ch, michel@daenzer.net,
	dri-devel@lists.freedesktop.org, ppaalanen@gmail.com,
	amd-gfx@lists.freedesktop.org, Daniel Vetter <daniel@ffwll.ch>,
	ckoenig.leichtzumerken@gmail.com, alexdeucher@gmail.com
Subject: Re: [PATCH v2 5/8] drm/amdgpu: Refactor sysfs removal
Date: Wed, 2 Dec 2020 18:34:58 +0100	[thread overview]
Message-ID: <X8fQQpYDqsgGJUPt@kroah.com> (raw)
In-Reply-To: <bc6cc476-4f09-1c0f-37b9-522723ecdc85@amd.com>

On Wed, Dec 02, 2020 at 10:48:01AM -0500, Andrey Grodzovsky wrote:
> 
> 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&amp;data=04%7C01%7CAndrey.Grodzovsky%40amd.com%7C9fbfecac94a340dfb68408d886571609%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637407055896651058%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=Ye8HJR1vidppcOBnlOgVu5GwKD2%2Bb5ztHbiI%2BubKKT0%3D&amp;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.

That's odd, why can't you just set the groups pointer in your pci_driver
structure?  That's what it is there for, right?

> 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.

Horrid, no, see above :)

thanks,

greg k-h
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