[Intel-gfx] [PATCH] drm/i915/gt: Take responsibility for engine->release as the last step

[Mika Kuoppala]

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

> In order to avoid a double cleanup on error, take ownership of
> engine->release past the point of no [error] return.
>
> Reported-by: Mika Kuoppala <mika.kuoppala at linux.intel.com>
> Fixes: e26b6d434147 ("drm/i915/gt: Pull GT initialisation under intel_gt_init()")
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>

fwiw, in the context of avoiding refcount underflow in error path,
Tested-by: Mika Kuoppala <mika.kuoppala at linux.intel.com>

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

> ---
>  drivers/gpu/drm/i915/gt/intel_lrc.c             | 4 +++-
>  drivers/gpu/drm/i915/gt/intel_ring_submission.c | 5 +++--
>  2 files changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
> index f6174e597dd3..5f171e43f79c 100644
> --- a/drivers/gpu/drm/i915/gt/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
> @@ -3925,7 +3925,6 @@ logical_ring_default_vfuncs(struct intel_engine_cs *engine)
>  {
>  	/* Default vfuncs which can be overriden by each engine. */
>  
> -	engine->release = execlists_release;
>  	engine->resume = execlists_resume;
>  
>  	engine->cops = &execlists_context_ops;
> @@ -4040,6 +4039,9 @@ int intel_execlists_submission_setup(struct intel_engine_cs *engine)
>  
>  	reset_csb_pointers(engine);
>  
> +	/* Finally, take ownership and responsibility for cleanup! */
> +	engine->release = execlists_release;
> +
>  	return 0;
>  }
>  
> diff --git a/drivers/gpu/drm/i915/gt/intel_ring_submission.c b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
> index 2e1478a48a4b..0525d67c6fc3 100644
> --- a/drivers/gpu/drm/i915/gt/intel_ring_submission.c
> +++ b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
> @@ -1840,8 +1840,6 @@ static void setup_common(struct intel_engine_cs *engine)
>  
>  	setup_irq(engine);
>  
> -	engine->release = ring_release;
> -
>  	engine->resume = xcs_resume;
>  	engine->reset.prepare = reset_prepare;
>  	engine->reset.rewind = reset_rewind;
> @@ -2007,6 +2005,9 @@ int intel_ring_submission_setup(struct intel_engine_cs *engine)
>  
>  	GEM_BUG_ON(timeline->hwsp_ggtt != engine->status_page.vma);
>  
> +	/* Finally, take ownership and responsibility for cleanup! */
> +	engine->release = ring_release;
> +
>  	return 0;
>  
>  err_ring:
> -- 
> 2.25.0.rc1