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

[Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>]

Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> writes:

> 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 :)

Not picky. Just my tinfoil hat too tight.

Reviewed-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>

> -Chris
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