[PATCH] drm/xe: sysfs_ops needs to be defined on parent directory
Rodrigo Vivi
rodrigo.vivi at intel.com
Wed Mar 26 14:43:24 UTC 2025
On Wed, Mar 26, 2025 at 04:14:21AM +0000, Upadhyay, Tejas wrote:
>
>
> > -----Original Message-----
> > From: Vivi, Rodrigo <rodrigo.vivi at intel.com>
> > Sent: Wednesday, March 26, 2025 12:43 AM
> > To: Upadhyay, Tejas <tejas.upadhyay at intel.com>
> > Cc: intel-xe at lists.freedesktop.org; Ghimiray, Himal Prasad
> > <himal.prasad.ghimiray at intel.com>
> > Subject: Re: [PATCH] drm/xe: sysfs_ops needs to be defined on parent
> > directory
> >
> > On Wed, Mar 19, 2025 at 05:43:49PM +0530, Tejas Upadhyay wrote:
> > > Currently, xe_hw_engine_sysfs_kobj_type is defining sysfs_ops on wrong
> > > directory. Sysfs_ops needs to be defined on immediate parent directory
> > > to be able to called on each attribute set/get.
> >
> > Please bare with me, but I'm having a hard time to follow this reasoning and
> > the patch, why, and everything else going on here...
> >
> > >
> > > Fixes: 3f0e14651ab0 ("drm/xe: Runtime PM wake on every sysfs call")
> >
> > Why this patch is claiming to fix this? Please note that this mentioned patch
> > just replace the default kobj_sysfs_ops per the new introduced
> > xe_hw_engine_class_sysfs_ops. They are basically identical functions.
> > The only difference is that the new one call our runtime pm wrappers around
> > the calls that we need.
>
> Earlier we were not doing any common ops for all attr set/get, each attribute has individual setter/getter. With 3f0e14651ab0 ("drm/xe: Runtime PM wake on every sysfs call"), we introduced common ops on all attr set/get and which is must to be called now. Thus I though of adding fixes. Please let me know if you guys think otherwise I will just remove, not strong objection.
I'm sorry for the noise. I probably had enough coffee today,
so yes, this is the right Fixes tag ;)
>
> >
> > It never touched anything that this patch is touching below.
> >
> > Perhaps if we also need on the sysfs on upper directory, perhaps we need to
> > also replace the default sysfs_ops on other places like in the upper directory?
> >
> > > Signed-off-by: Tejas Upadhyay <tejas.upadhyay at intel.com>
> > > ---
> > > drivers/gpu/drm/xe/xe_hw_engine_class_sysfs.c | 67
> > > +++++++++----------
> > > 1 file changed, 33 insertions(+), 34 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/xe/xe_hw_engine_class_sysfs.c
> > > b/drivers/gpu/drm/xe/xe_hw_engine_class_sysfs.c
> > > index b53e8d2accdb..25592f178482 100644
> > > --- a/drivers/gpu/drm/xe/xe_hw_engine_class_sysfs.c
> > > +++ b/drivers/gpu/drm/xe/xe_hw_engine_class_sysfs.c
> > > @@ -492,39 +492,6 @@ static const struct attribute * const files[] = {
> > > NULL
> > > };
> > >
> > > -static void kobj_xe_hw_engine_class_fini(void *arg) -{
> > > - struct kobject *kobj = arg;
> > > -
> > > - sysfs_remove_files(kobj, files);
> > > - kobject_put(kobj);
> > > -}
> > > -
> > > -static struct kobj_eclass *
> > > -kobj_xe_hw_engine_class(struct xe_device *xe, struct kobject *parent,
> > > const char *name) -{
> > > - struct kobj_eclass *keclass;
> > > - int err = 0;
> > > -
> > > - keclass = kzalloc(sizeof(*keclass), GFP_KERNEL);
> > > - if (!keclass)
> > > - return NULL;
> > > -
> > > - kobject_init(&keclass->base, &kobj_xe_hw_engine_type);
> > > - if (kobject_add(&keclass->base, parent, "%s", name)) {
> > > - kobject_put(&keclass->base);
> > > - return NULL;
> > > - }
> > > - keclass->xe = xe;
> > > -
> > > - err = devm_add_action_or_reset(xe->drm.dev,
> > kobj_xe_hw_engine_class_fini,
> > > - &keclass->base);
> > > - if (err)
> > > - return NULL;
> > > -
> > > - return keclass;
> > > -}
> > > -
> > > static void hw_engine_class_defaults_fini(void *arg) {
> > > struct kobject *kobj = arg;
> > > @@ -611,6 +578,38 @@ static const struct kobj_type
> > xe_hw_engine_sysfs_kobj_type = {
> > > .sysfs_ops = &xe_hw_engine_class_sysfs_ops, };
> > >
> > > +static void kobj_xe_hw_engine_class_fini(void *arg) {
> > > + struct kobject *kobj = arg;
> > > +
> > > + sysfs_remove_files(kobj, files);
> > > + kobject_put(kobj);
> > > +}
> > > +
> > > +static struct kobj_eclass *
> > > +kobj_xe_hw_engine_class(struct xe_device *xe, struct kobject *parent,
> > > +const char *name) {
> > > + struct kobj_eclass *keclass;
> > > + int err = 0;
> > > +
> > > + keclass = kzalloc(sizeof(*keclass), GFP_KERNEL);
> > > + if (!keclass)
> > > + return NULL;
> > > +
> > > + kobject_init(&keclass->base, &xe_hw_engine_sysfs_kobj_type);
> > > + if (kobject_add(&keclass->base, parent, "%s", name)) {
> > > + kobject_put(&keclass->base);
> > > + return NULL;
> > > + }
> > > + keclass->xe = xe;
> > > +
> > > + err = devm_add_action_or_reset(xe->drm.dev,
> > kobj_xe_hw_engine_class_fini,
> > > + &keclass->base);
> > > + if (err)
> > > + return NULL;
> > > +
> > > + return keclass;
> > > +}
> >
> > I couldn't spot any difference from the both chunks above. So this patch is
> > more moving things around than doing any change right? perhaps a different
> > patch or a mention on the commit message itself?
>
> The change is, immediate parent directory should be defined with attr_show/store ops if we want it to be called on every attr set/get call. Currently we had sysfs_ops defined on parent to parent directory which does not get called on underlying child's attr set/get call.
Okay, now I could spot the change:
inside kobj_xe_hw_engine_class()
- kobject_init(&keclass->base, &kobj_xe_hw_engine_type);
+ kobject_init(&keclass->base, &xe_hw_engine_sysfs_kobj_type);
and inside xe_hw_engine_class_sysfs_init()
- kobject_init(kobj, &xe_hw_engine_sysfs_kobj_type);
+ kobject_init(kobj, &kobj_xe_hw_engine_type);
With this you invert where the runtime_pm is called moving it to the right parent.
I partially agree with the fix, but I don't agree with the patch itself.
Not only because I got confused, but because it creates inconsistency:
kobj_xe_hw_engine_class now uses xe_hw_engine_sysfs_kobj_type
and
xe_hw_engine_class_sysfs_init now uses kobj_xe_hw_engine_type
If we want to invert, we need to invert the sysfs_ops inside the type functions.
But also, I don't believe that there is the problem on leaving the runtime_pm
hooks in the parent of parent. Just in case we end up adding some extra file
there.
So, What about simply:
static const struct kobj_type kobj_xe_hw_engine_type = {
.release = kobj_xe_hw_engine_release,
- .sysfs_ops = &kobj_sysfs_ops
+ .sysfs_ops = &xe_hw_engine_class_sysfs_ops,
};
Thanks for catching that up and fixing it,
Rodrigo.
>
> Tejas
> >
> > > static void hw_engine_class_sysfs_fini(void *arg) {
> > > struct kobject *kobj = arg;
> > > @@ -640,7 +639,7 @@ int xe_hw_engine_class_sysfs_init(struct xe_gt *gt)
> > > if (!kobj)
> > > return -ENOMEM;
> > >
> > > - kobject_init(kobj, &xe_hw_engine_sysfs_kobj_type);
> > > + kobject_init(kobj, &kobj_xe_hw_engine_type);
> >
> > now it looks like this is the only real chunk of this patch, last touched when
> > you added it:
> > 038ff941afe2 ("drm/xe: Add sysfs entries for engines under its GT")
> >
> > And now, after this patch, who is now using xe_hw_engine_sysfs_kobj_type?
> >
> > Looking further to both types, perhaps we need to kill the
> > kobj_xe_hw_engine_type itself in favor of the xe_ one?
> >
> > Or perhaps we need something like this:
> >
> > static const struct kobj_type kobj_xe_hw_engine_type = {
> > .release = kobj_xe_hw_engine_release,
> > - .sysfs_ops = &kobj_sysfs_ops
> > + .sysfs_ops = &xe_hw_engine_class_sysfs_ops,
> > };
> >
> > >
> > > err = kobject_add(kobj, gt->sysfs, "engines");
> > > if (err)
> > > --
> > > 2.34.1
> > >
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