On Mon, Aug 08, 2016 at 08:28:48AM +0100, Chris Wilson wrote:
> When we force the cleanup after a GPU hang, we want to retire all
> requests, or else we may leak them if truly wedged (and the GPU never
> advances again). Converting to the active request helpers had the issue
> of doing the check against busyness before reporting the request, so if
> we claim the GPU had hung but this engine hadn't we could potential skip
> the request cleanup - triggering the self-check BUG.
>
> Fixes: dcff85c8443e ("drm/i915: Enable i915_gem_wait_for_idle() ...")
Was confused for a while why this is a problem du to lockless
wait_for_idle until I realized that that patch also converted the engine
reset cleanup over to the new active helpers.
Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_gem.c | 8 +++-----
> 1 file changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index f4f8eaa90f2a..cd5229301aae 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -2423,15 +2423,11 @@ static void i915_gem_reset_engine_cleanup(struct intel_engine_cs *engine)
> struct drm_i915_gem_request *request;
> struct intel_ring *ring;
>
> - request = i915_gem_active_peek(&engine->last_request,
> - &engine->i915->drm.struct_mutex);
> -
> /* Mark all pending requests as complete so that any concurrent
> * (lockless) lookup doesn't try and wait upon the request as we
> * reset it.
> */
> - if (request)
> - intel_engine_init_seqno(engine, request->fence.seqno);
> + intel_engine_init_seqno(engine, engine->last_submitted_seqno);
>
> /*
> * Clear the execlists queue up before freeing the requests, as those
> @@ -2453,6 +2449,8 @@ static void i915_gem_reset_engine_cleanup(struct intel_engine_cs *engine)
> * implicit references on things like e.g. ppgtt address spaces through
> * the request.
> */
> + request = i915_gem_active_raw(&engine->last_request,
> + &engine->i915->drm.struct_mutex);
> if (request)
> i915_gem_request_retire_upto(request);
> GEM_BUG_ON(intel_engine_is_active(engine));
> --
> 2.8.1
>
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--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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