Re: [PATCH 6/6] drm/i915/gt: Lift set-wedged engine dumping out of user paths

[Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>]

Quoting Mika Kuoppala (2020-01-28 12:34:42)
> Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> writes:
> 
> > The user (e.g. gem_eio) can manipulate the driver into wedging itself,
> > allowing the user to trigger voluminous logging of inconsequential
> > details. If we lift the dump to direct calls to intel_gt_set_wedged(),
> > out of the intel_reset failure handling, we keep the detail logging for
> > what we expect are true HW or test failures without being tricked.
> >
> > Reported-by: Tomi Sarvela <tomi.p.sarvela@xxxxxxxxx>
> > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> > Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
> > Cc: Tomi Sarvela <tomi.p.sarvela@xxxxxxxxx>
> > ---
> >  drivers/gpu/drm/i915/gt/intel_reset.c | 30 +++++++++++++++++++--------
> >  1 file changed, 21 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/gt/intel_reset.c b/drivers/gpu/drm/i915/gt/intel_reset.c
> > index beee0cf89bce..423a02506b2d 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_reset.c
> > +++ b/drivers/gpu/drm/i915/gt/intel_reset.c
> > @@ -800,13 +800,6 @@ static void __intel_gt_set_wedged(struct intel_gt *gt)
> >       if (test_bit(I915_WEDGED, &gt->reset.flags))
> >               return;
> >  
> > -     if (GEM_SHOW_DEBUG() && !intel_engines_are_idle(gt)) {
> > -             struct drm_printer p = drm_debug_printer(__func__);
> > -
> > -             for_each_engine(engine, gt, id)
> > -                     intel_engine_dump(engine, &p, "%s\n", engine->name);
> > -     }
> > -
> >       GT_TRACE(gt, "start\n");
> >  
> >       /*
> > @@ -845,10 +838,29 @@ void intel_gt_set_wedged(struct intel_gt *gt)
> >  {
> >       intel_wakeref_t wakeref;
> >  
> > +     if (test_bit(I915_WEDGED, &gt->reset.flags))
> > +             return;
> > +
> > +     wakeref = intel_runtime_pm_get(gt->uncore->rpm);
> >       mutex_lock(&gt->reset.mutex);
> > -     with_intel_runtime_pm(gt->uncore->rpm, wakeref)
> > -             __intel_gt_set_wedged(gt);
> > +
> > +     if (GEM_SHOW_DEBUG() && !intel_engines_are_idle(gt)) {
> 
> As you inspect each engine separately the precursory idle check
> seems superfluous.

Picky. We may throw some other debug in between :)
-Chris
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