[Intel-gfx] [PATCH] drm/i915: Defer application of request banning to submission

[Mika Kuoppala]

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

> As we currently do not check on submission whether the context is banned
> in a timely manner it is possible for some requests to escape
> cancellation after their parent context is banned. By moving the ban
> into the request submission under the engine->timeline.lock, we
> serialise it with the reset and setting of the context ban.
>
> References: eb8d0f5af4ec ("drm/i915: Remove GPU reset dependence on struct_mutex")
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Mika Kuoppala <mika.kuoppala at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_request.c |  3 +++
>  drivers/gpu/drm/i915/i915_reset.c   | 19 +++++--------------
>  2 files changed, 8 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
> index 0acd6baa3c88..5ab4e1c01618 100644
> --- a/drivers/gpu/drm/i915/i915_request.c
> +++ b/drivers/gpu/drm/i915/i915_request.c
> @@ -366,6 +366,9 @@ void __i915_request_submit(struct i915_request *request)
>  	GEM_BUG_ON(!irqs_disabled());
>  	lockdep_assert_held(&engine->timeline.lock);
>  
> +	if (i915_gem_context_is_banned(request->gem_context))
> +		i915_request_skip(request, -EIO);
> +
>  	GEM_BUG_ON(request->global_seqno);
>  
>  	seqno = next_global_seqno(&engine->timeline);
> diff --git a/drivers/gpu/drm/i915/i915_reset.c b/drivers/gpu/drm/i915/i915_reset.c
> index 12e74decd7a2..7fa97ce19bfd 100644
> --- a/drivers/gpu/drm/i915/i915_reset.c
> +++ b/drivers/gpu/drm/i915/i915_reset.c
> @@ -22,24 +22,15 @@ static void engine_skip_context(struct i915_request *rq)
>  {
>  	struct intel_engine_cs *engine = rq->engine;
>  	struct i915_gem_context *hung_ctx = rq->gem_context;
> -	struct i915_timeline *timeline = rq->timeline;
>  
>  	lockdep_assert_held(&engine->timeline.lock);

This was golden.

> -	GEM_BUG_ON(timeline == &engine->timeline);
>  
> -	spin_lock(&timeline->lock);
> -
> -	if (i915_request_is_active(rq)) {
> -		list_for_each_entry_continue(rq,
> -					     &engine->timeline.requests, link)
> -			if (rq->gem_context == hung_ctx)
> -				i915_request_skip(rq, -EIO);
> -	}
> -
> -	list_for_each_entry(rq, &timeline->requests, link)
> -		i915_request_skip(rq, -EIO);
> +	if (!i915_request_is_active(rq))
> +		return;

Only thing that got me actually pondering was that
we don't flush anything after we have modify the ring.

But that is not about this patch

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


>  
> -	spin_unlock(&timeline->lock);
> +	list_for_each_entry_continue(rq, &engine->timeline.requests, link)
> +		if (rq->gem_context == hung_ctx)
> +			i915_request_skip(rq, -EIO);
>  }
>  
>  static void client_mark_guilty(struct drm_i915_file_private *file_priv,
> -- 
> 2.20.1
>
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