[PATCH 3/3] drm/debugfs: remove dev->debugfs_list and debugfs_mutex

[Stanislaw Gruszka]

On Fri, Feb 17, 2023 at 12:49:41PM +0200, Jani Nikula wrote:
> On Fri, 17 Feb 2023, Stanislaw Gruszka <stanislaw.gruszka at linux.intel.com> wrote:
> > On Thu, Feb 16, 2023 at 07:06:46PM +0200, Jani Nikula wrote:
> >> >
> >> > But should not this the driver responsibility, call drm_debugfs_add_file()
> >> > whenever you are ready to handle operations on added file ?
> >> 
> >> In theory, yes, but in practice it's pretty hard for a non-trivial
> >> driver to maintain that all the conditions are met.
> >
> > Hmmm... 
> >
> >> In i915 we call debugfs register all over the place only after we've
> >> called drm_dev_register(), because it's the only sane way. But it means
> >> we need the init and register separated everywhere, instead of init
> >> adding files to a list to be registered later.
> >
> > Isn't this done this way in i915 only because it was not possible
> > (and still isn't) to call drm_debugfs_create_file() before registration ?
> >
> > I think it's should be ok by i915 subsystem to create it's debugfs
> > files and allow to access to them just after that subsystem init.
> >
> > Or there are some complex dependencies between i915 subsystems,
> > that reading registers from one subsystem will corrupt some
> > other subsystem that did non finish initialization yet?
> 
> That's the point. It's really hard to figure it all out. Why bother?

I see. 

Just hope we could get something simpler to limit debugfs access
before registration: unix hidden file, permissions or other way.
Because current drm_debufs_add_file() implementation looks
really over convoluted to me.

Regards
Stanislaw