Re: [PATCH] drm/i915/selftests: Hold rpm for unparking

[Mika Kuoppala <mika.kuoppala@linux.intel.com>]

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

> The call to i915_gem_unpark() checks that we hold a rpm wakeref before
> taking a long term wakeref for i915->gt.awake. We should therefore make
> sure we do hold the wakeref when directly calling unpark to disable
> the retire worker.

We as a caller need to hold the rpm as i915_gem_unpark does 
intel_runtime_pm_get_noresume() ?

As I don't see any other checks before gt.awake being set.

-Mika

>
> Fixes: 932cac10c8fb ("drm/i915/selftests: Prevent background reaping of active objects")
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
> Cc: Matthew Auld <matthew.auld@intel.com>
> ---
>  .../gpu/drm/i915/selftests/i915_gem_object.c  | 20 +++++++++++++------
>  1 file changed, 14 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/selftests/i915_gem_object.c b/drivers/gpu/drm/i915/selftests/i915_gem_object.c
> index d9eca1b02aee..6d3516d5bff9 100644
> --- a/drivers/gpu/drm/i915/selftests/i915_gem_object.c
> +++ b/drivers/gpu/drm/i915/selftests/i915_gem_object.c
> @@ -499,6 +499,19 @@ static bool assert_mmap_offset(struct drm_i915_private *i915,
>  	return err == expected;
>  }
>  
> +static void disable_retire_worker(struct drm_i915_private *i915)
> +{
> +	mutex_lock(&i915->drm.struct_mutex);
> +	if (!i915->gt.active_requests++) {
> +		intel_runtime_pm_get(i915);
> +		i915_gem_unpark(i915);
> +		intel_runtime_pm_put(i915);
> +	}
> +	mutex_unlock(&i915->drm.struct_mutex);
> +	cancel_delayed_work_sync(&i915->gt.retire_work);
> +	cancel_delayed_work_sync(&i915->gt.idle_work);
> +}
> +
>  static int igt_mmap_offset_exhaustion(void *arg)
>  {
>  	struct drm_i915_private *i915 = arg;
> @@ -509,12 +522,7 @@ static int igt_mmap_offset_exhaustion(void *arg)
>  	int loop, err;
>  
>  	/* Disable background reaper */
> -	mutex_lock(&i915->drm.struct_mutex);
> -	if (!i915->gt.active_requests++)
> -		i915_gem_unpark(i915);
> -	mutex_unlock(&i915->drm.struct_mutex);
> -	cancel_delayed_work_sync(&i915->gt.retire_work);
> -	cancel_delayed_work_sync(&i915->gt.idle_work);
> +	disable_retire_worker(i915);
>  	GEM_BUG_ON(!i915->gt.awake);
>  
>  	/* Trim the device mmap space to only a page */
> -- 
> 2.18.0
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