[Intel-gfx] [PATCH 2/3] drm/i915: Fix fbdev unload sequence
Chris Wilson
chris at chris-wilson.co.uk
Fri Jul 14 19:30:34 UTC 2017
Quoting Daniel Vetter (2017-07-14 20:14:38)
> First thing we need to do is unregister the fbdev instance, but we
> can't just go ahead and kfree it. That must wait until the hotplug and
> polling work are stopped, since they can race with the with the
> teardown. That means we need to split up the fbdev teardown into the
> unregister part and the cleanup part.
>
> I originally suspected that this was broken in one of the unload
> shuffles, but on closer inspection the oldest sequence I've dug out
> also gets this wrong. Just not quite so badly.
>
> I've run drv_module_reload a few hundred times and it's rock solid
> compared to insta-death beforehand. This bug seems to have been
> uncovered by
>
> commit 88be58be886f1215cc73dc8c273c985eecd7385c
> Author: Daniel Vetter <daniel.vetter at ffwll.ch>
> Date: Thu Jul 6 15:00:19 2017 +0200
>
> drm/i915/fbdev: Always forward hotplug events
>
> But the effect of that seems to only be to increase the race window
> enough to make it blow up easier. I'm not exactly clear on what's
> going on there ...
>
> Testcase: igt/drv_module_reload
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101791
> Cc: martin.peres at free.fr
> Cc: chris at chris-wilson.co.uk
> Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
Splitting out the unregister and running it early makes sense and is how
we expect to unload to proceed.
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
Nit:
> @@ -1383,7 +1383,6 @@ void i915_driver_unload(struct drm_device *dev)
> intel_gvt_cleanup(dev_priv);
>
> i915_driver_unregister(dev_priv);
> -
> intel_modeset_cleanup(dev);
I think it will useful to maintain the visual break here. (I know next
patch moves it again...)
-Chris
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