[Intel-gfx] [PATCH 12/40] drm/i915/execlists: Assert the queue is non-empty on unsubmitting

[Tvrtko Ursulin]

On 19/09/2018 20:55, Chris Wilson wrote:
> In the sequence
> 
> <0>[  531.960431] drv_self-4806    7.... 527402570us : intel_gpu_reset: engine_mask=1, ret=0, retry=0
> <0>[  531.960431] drv_self-4806    7.... 527402571us : execlists_reset: rcs0 request global=115de, current=71133

How such a unbelievably huge delta between the guilty request and hws?

> <0>[  531.960431] drv_self-4806    7d..1 527402571us : execlists_cancel_port_requests: rcs0:port0 global=71134 (fence 826b:198), (current 71133)
> <0>[  531.960431] drv_self-4806    7d..1 527402572us : execlists_cancel_port_requests: rcs0:port1 global=71135 (fence 826c:53), (current 71133)
> <0>[  531.960431] drv_self-4806    7d..1 527402572us : __i915_request_unsubmit: rcs0 fence 826c:53 <- global=71135, current 71133
> <0>[  531.960431] drv_self-4806    7d..1 527402579us : __i915_request_unsubmit: rcs0 fence 826b:198 <- global=71134, current 71133
> <0>[  531.960431] drv_self-4806    7.... 527402613us : intel_engine_cancel_stop_cs: rcs0
> <0>[  531.960431] drv_self-4806    7.... 527402624us : execlists_reset_finish: rcs0
> 
> we are missing the execlists_submission_tasklet() invocation before the
> execlists_reset_fini() implying that either the queue is empty, or we
> failed to schedule and run the tasklet on finish. Add an assert so we
> are sure that on unsubmitting the incomplete request after reset, the
> queue is indeed populated.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> ---
>   drivers/gpu/drm/i915/intel_lrc.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
> index 3edb417caa7b..e8de250c3413 100644
> --- a/drivers/gpu/drm/i915/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/intel_lrc.c
> @@ -344,6 +344,7 @@ static void __unwind_incomplete_requests(struct intel_engine_cs *engine)
>   			last_prio = rq_prio(rq);
>   			p = lookup_priolist(engine, last_prio);
>   		}
> +		GEM_BUG_ON(RB_EMPTY_ROOT(&engine->execlists.queue.rb_root));
>   
>   		GEM_BUG_ON(p->priority != rq_prio(rq));
>   		list_add(&rq->sched.link, &p->requests);
> 

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

Regards,

Tvrtko