[Intel-gfx] [PATCH] drm/i915/selftests: Drop struct_mutex around lowlevel pggtt allocation

[Tvrtko Ursulin]

On 03/07/2018 11:07, Chris Wilson wrote:
> For a ppgtt that we are constructing, there is no struct_mutex
> dependence so skip it. In the process, also ping the scheduler
> frequently to try and avoid the NMI watchdog.
> 
> Suggested-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> References: https://bugs.freedesktop.org/show_bug.cgi?id=107094
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> ---
>   drivers/gpu/drm/i915/selftests/i915_gem_gtt.c | 13 ++++++-------
>   1 file changed, 6 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c b/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c
> index a28ee0cc6a63..fff26bd05f71 100644
> --- a/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c
> @@ -142,12 +142,9 @@ static int igt_ppgtt_alloc(void *arg)
>   	if (!USES_PPGTT(dev_priv))
>   		return 0;
>   
> -	mutex_lock(&dev_priv->drm.struct_mutex);
>   	ppgtt = __hw_ppgtt_create(dev_priv);
> -	if (IS_ERR(ppgtt)) {
> -		err = PTR_ERR(ppgtt);
> -		goto err_unlock;
> -	}
> +	if (IS_ERR(ppgtt))
> +		return PTR_ERR(ppgtt);
>   
>   	if (!ppgtt->vm.allocate_va_range)
>   		goto err_ppgtt_cleanup;
> @@ -166,6 +163,8 @@ static int igt_ppgtt_alloc(void *arg)
>   			goto err_ppgtt_cleanup;
>   		}
>   
> +		cond_resched();
> +

This test is also long running? Seeing how it allocates in growing 
chunks I expected it would finish quick, but it would not?

Regards,

Tvrtko

>   		ppgtt->vm.clear_range(&ppgtt->vm, 0, size);
>   	}
>   
> @@ -183,13 +182,13 @@ static int igt_ppgtt_alloc(void *arg)
>   			}
>   			goto err_ppgtt_cleanup;
>   		}
> +
> +		cond_resched();
>   	}
>   
>   err_ppgtt_cleanup:
>   	ppgtt->vm.cleanup(&ppgtt->vm);
>   	kfree(ppgtt);
> -err_unlock:
> -	mutex_unlock(&dev_priv->drm.struct_mutex);
>   	return err;
>   }
>   
>