[PATCH 00/19] drm: debugfs: Remove all files automatically on cleanup

[Daniel Vetter]

On Fri, Jan 27, 2017 at 10:36:16AM +0100, Thierry Reding wrote:
> On Fri, Jan 27, 2017 at 08:49:34AM +0100, Daniel Vetter wrote:
> > On Thu, Jan 26, 2017 at 11:56:02PM +0100, Noralf Trønnes wrote:
> > > This patchset removes the need for drivers to clean up their debugfs
> > > files on exit. It is done automatically in drm_debugfs_cleanup().
> > > This funtion is also called should the driver error out in it's
> > > drm_driver.debugfs_init callback.
> > > 
> > > Two drivers still use drm_debugfs_remove_files():
> > > - tegra in it's connectors, not sure if I can remove it.
> > 
> > I read through them, and they're removed on the component device nodes
> > stuff. That looks somewhat fishy from a lifetime point of view, and I
> > think removing all that code would be better, too.
> 
> What makes you think that's problematic from a lifetime point of view?
> The component device is tied to the DRM device, so these callbacks are
> called at the right time.

debugfs is a userspace interface, which should disappear when
drm_dev_unregister gets called. I'm not sure at all whether that lines up
with the cleanup of all your component nodes, but otoh it's rather
academic since you can't hotplug a tegra.

> That said, I think it's safe to remove the other debugfs files from
> Tegra. It might not be possible to remove the cleanup functions
> altogether, though, because they have to do a special dance involving
> kmemdup() drm_debugfs_create_files() and kfree() in order to support
> debugfs files for multiple instances of subdevices.

Hm, that entire "do debugfs on the minor" thing makes almost never sense.
All the things we have left in modern drivers are either per-fd, or
per-device. Nothing of interest is per-minor. Or do you mean something
else?

Either way would be nice if we can remove them too, so that
drm_debugfs_remove_files could be unexported ...
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch