[Intel-gfx] [PATCH] drm/i915/gt: Ignore error capturing a closed context

[Mika Kuoppala]

Chris Wilson <chris at chris-wilson.co.uk> writes:

> To capture a context after a gpu hang, we suspend the request and then
> resume its execution afterwards. If the context is already closed, we
> can assume that no one is interested in the result, but instead we are
> trying to terminate execution quickly as part of a forced-preemption.
> In which case, do not waste time in suspending the request, capturing
> the error, and just cancel it instead.
>
> Testcase: igt/gem_ctx_persistence/many-contexts
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>

Reviewed-by: Mika Kuoppala <mika.kuoppala at linux.intel.com>

> ---
>  .../drm/i915/gt/intel_execlists_submission.c   | 18 +++++++++++++-----
>  1 file changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> index e20ab2eab3a8..2280d1bd2c77 100644
> --- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> +++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> @@ -2249,10 +2249,21 @@ static u32 active_ccid(struct intel_engine_cs *engine)
>  static void execlists_capture(struct intel_engine_cs *engine)
>  {
>  	struct execlists_capture *cap;
> +	struct i915_request *rq;
>  
>  	if (!IS_ENABLED(CONFIG_DRM_I915_CAPTURE_ERROR))
>  		return;
>  
> +	rq = active_context(engine, active_ccid(engine));
> +
> +	/*
> +	 * If the context is closed, assume no one is listening for the
> +	 * associated state; the user is already gone. We can save a lot of
> +	 * time around forced-preemption by just cancelling the guilty request.
> +	 */
> +	if (!rq || intel_context_is_closed(rq->context))
> +		return;
> +
>  	/*
>  	 * We need to _quickly_ capture the engine state before we reset.
>  	 * We are inside an atomic section (softirq) here and we are delaying
> @@ -2262,11 +2273,8 @@ static void execlists_capture(struct intel_engine_cs *engine)
>  	if (!cap)
>  		return;
>  
> -	cap->rq = active_context(engine, active_ccid(engine));
> -	if (cap->rq) {
> -		cap->rq = active_request(cap->rq->context->timeline, cap->rq);
> -		cap->rq = i915_request_get_rcu(cap->rq);
> -	}
> +	rq = active_request(rq->context->timeline, rq);
> +	cap->rq = i915_request_get_rcu(rq);
>  	if (!cap->rq)
>  		goto err_free;
>  
> -- 
> 2.20.1
>
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