Re: [Intel-gfx] [PATCH 1/3] drm: Restore driver.preclose() for all to use

[Chris Wilson <chris@chris-wilson.co.uk>]

Quoting Daniel Vetter (2020-07-27 20:32:45)
> On Thu, Jul 23, 2020 at 7:21 PM Chris Wilson <chris@chris-wilson.co.uk> wrote:
> >
> > An unfortunate sequence of events, but it turns out there is a valid
> > usecase for being able to free/decouple the driver objects before they
> > are freed by the DRM core. In particular, if we have a pointer into a
> > drm core object from inside a driver object, that pointer needs to be
> > nerfed *before* it is freed so that concurrent access (e.g. debugfs)
> > does not following the dangling pointer.
> >
> > The legacy marker was adding in the code movement from drp_fops.c to
> > drm_file.c
> 
> I might fumble a lot, but not this one:
> 
> commit 45c3d213a400c952ab7119f394c5293bb6877e6b
> Author: Daniel Vetter <daniel.vetter@ffwll.ch>
> Date:   Mon May 8 10:26:33 2017 +0200
> 
>     drm: Nerf the preclose callback for modern drivers

Gah, when I going through the history it looked like it appeared out of
nowhere.

> Also looking at the debugfs hook that has some rather adventurous
> stuff going on I think, feels a bit like a kitchensink with batteries
> included. If that's really all needed I'd say iterate the contexts by
> first going over files, then the ctx (which arent shared anyway) and
> the problem should also be gone.

Or we could cut out the middlelayer and put the release under the driver
control with a call to the drm_release() when the driver is ready.
-Chris
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