[Intel-gfx] [PATCH] drm/i915: Drain the device workqueue on unload

[Chris Wilson]

Quoting Mika Kuoppala (2017-06-29 10:07:04)
> Chris Wilson <chris at chris-wilson.co.uk> writes:
> 
> > Workers on the i915->wq may rearm themselves so for completeness we need
> > to replace our flush_workqueue() with a call to drain_workqueue() before
> > unloading the device.
> >
> > References: https://bugs.freedesktop.org/show_bug.cgi?id=101627
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Matthew Auld <matthew.auld at intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_drv.c                  | 2 +-
> >  drivers/gpu/drm/i915/selftests/mock_gem_device.c | 2 +-
> >  2 files changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> > index 9167a73f3c69..3f998d7102f7 100644
> > --- a/drivers/gpu/drm/i915/i915_drv.c
> > +++ b/drivers/gpu/drm/i915/i915_drv.c
> > @@ -592,7 +592,7 @@ static const struct vga_switcheroo_client_ops i915_switcheroo_ops = {
> >  
> >  static void i915_gem_fini(struct drm_i915_private *dev_priv)
> >  {
> > -     flush_workqueue(dev_priv->wq);
> > +     drain_workqueue(dev_priv->wq);
> 
> There will be superfluous drain_workqueue in driver_unload.
> 
> Also the destroy will drain byitself but in here we want
> to drain before taking mutex?

Yes. Some fini functions (e.g. i915_gem_contexts_fini) rely on there
being no pending work left and can safely destroy the parent structures.
-Chris