Re: [PATCH 09/14] drm/exynos: remove call to drm_gem_free_mmap_offset()

[Inki Dae <inki.dae@samsung.com>]

On 2015년 07월 28일 17:53, Joonyoung Shim wrote:
> The drm_gem_object_release() function already performs this cleanup,
> so there is no reason to do it explicitly.
> 
> Signed-off-by: Joonyoung Shim <jy0922.shim@samsung.com>
> ---
>  drivers/gpu/drm/exynos/exynos_drm_gem.c | 3 ---
>  1 file changed, 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_gem.c b/drivers/gpu/drm/exynos/exynos_drm_gem.c
> index c76aa8a..ab7d029 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_gem.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_gem.c
> @@ -100,8 +100,6 @@ out:
>  	exynos_drm_fini_buf(obj->dev, buf);
>  	exynos_gem_obj->buffer = NULL;
>  
> -	drm_gem_free_mmap_offset(obj);
> -
>  	/* release file pointer to gem object. */
>  	drm_gem_object_release(obj);
>  
> @@ -600,7 +598,6 @@ int exynos_drm_gem_mmap(struct file *filp, struct vm_area_struct *vma)
>  
>  err_close_vm:
>  	drm_gem_vm_close(vma);
> -	drm_gem_free_mmap_offset(obj);

Without previous patch, drm_gem_free_mmap_offset is required. I guess
the reason you removed above line is that you thought
drm_gem_object_release function would be called by drm_gem_vm_close
function which drops a reference of the gem object.

However, drm_gem_vm_close should be a pair with drm_gem_vm_open
function. These will be called whenever a process opens or closes the
VMA. So the reference count of the gem object had already been taken by
open operation when a new reference to the VMA had been created.

Thanks,
Inki Dae

>  
>  	return ret;
>  }
> 

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