[Intel-gfx] [PATCH 04/10] drm/i915: Use explicit flag to mark unreachable intel_context

[Chris Wilson]

Quoting Tvrtko Ursulin (2020-03-18 12:11:33)
> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> 
> I need to keep the GEM context around a bit longer so adding an explicit
> flag for syncing execbuf with closed/abandonded contexts.
> 
> v2:
>  * Use already available context flags. (Chris)
> 
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> ---
>  drivers/gpu/drm/i915/gem/i915_gem_context.c    | 3 ++-
>  drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c | 2 +-
>  drivers/gpu/drm/i915/gt/intel_context_types.h  | 1 +
>  3 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
> index 9afc60ab95e0..7c119a3a2cbd 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
> @@ -579,7 +579,8 @@ static void engines_idle_release(struct i915_gem_context *ctx,
>                 int err = 0;
>  
>                 /* serialises with execbuf */
> -               RCU_INIT_POINTER(ce->gem_context, NULL);
> +               set_bit(INTEL_CONTEXT_CLOSED, &ce->flags);
> +
>                 if (!intel_context_pin_if_active(ce))
>                         continue;
>  
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> index d3f4f28e9468..875da020d6c8 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> @@ -2316,7 +2316,7 @@ static void eb_request_add(struct i915_execbuffer *eb)
>         prev = __i915_request_commit(rq);
>  
>         /* Check that the context wasn't destroyed before submission */
> -       if (likely(rcu_access_pointer(eb->context->gem_context))) {
> +       if (likely(!test_bit(INTEL_CONTEXT_CLOSED, &eb->context->flags))) {
>                 attr = eb->gem_context->sched;
>  
>                 /*
> diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h
> index 0f3b68b95c56..d5925c25f109 100644
> --- a/drivers/gpu/drm/i915/gt/intel_context_types.h
> +++ b/drivers/gpu/drm/i915/gt/intel_context_types.h
> @@ -66,6 +66,7 @@ struct intel_context {
>  #define CONTEXT_BANNED                 4
>  #define CONTEXT_FORCE_SINGLE_SUBMISSION        5
>  #define CONTEXT_NOPREEMPT              6
> +#define INTEL_CONTEXT_CLOSED           7

Trying to start a flame war? :)

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

With this flag, we can start banning contexts after a GPU hang on a
closed context _again_. That might justify applying immediately.
-Chris