[Intel-gfx] [PATCH 10/11] drm/i915: Skip holding a reference to the execbuffer objects

[Daniel Vetter]

On Tue, Jan 08, 2013 at 10:53:18AM +0000, Chris Wilson wrote:
> As we only maintain the list underneath the struct_mutex, we can hold a
> 'borrowed' reference to the objects safe in the knowledge that they will
> not disappear.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>

Ok, after our irc discussion I've checked things at this patch looks
correct. I still think it's too fancy, and generally I'd like to reduce
our reliance on dev->struct_mutex serialization effects, not increase it:
Sooner or later we'll have to deal with some form of per-object locking
... Hence I'll punt on this one here.
-Daniel

> ---
>  drivers/gpu/drm/i915/i915_gem_execbuffer.c |    3 ---
>  1 file changed, 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> index 18a6ab7..f6bd92c 100644
> --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> @@ -111,7 +111,6 @@ eb_lookup_objects(struct eb_objects *eb,
>  			return -EINVAL;
>  		}
>  
> -		drm_gem_object_reference(&obj->base);
>  		list_add_tail(&obj->exec_list, &eb->objects);
>  
>  		obj->exec_entry = &exec[i];
> @@ -162,7 +161,6 @@ eb_destroy(struct eb_objects *eb)
>  				       struct drm_i915_gem_object,
>  				       exec_list);
>  		list_del_init(&obj->exec_list);
> -		drm_gem_object_unreference(&obj->base);
>  	}
>  	kfree(eb);
>  }
> @@ -603,7 +601,6 @@ i915_gem_execbuffer_relocate_slow(struct drm_device *dev,
>  				       struct drm_i915_gem_object,
>  				       exec_list);
>  		list_del_init(&obj->exec_list);
> -		drm_gem_object_unreference(&obj->base);
>  	}
>  
>  	mutex_unlock(&dev->struct_mutex);
> -- 
> 1.7.10.4
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch