[PATCH 8/9] drm/shmem-helpers: Ensure get_pages is not called on imported dma-buf

[Thomas Zimmermann]

Hi

Am 11.05.20 um 11:35 schrieb Daniel Vetter:
> Just a bit of light paranoia. Also sprinkle this check over
> drm_gem_shmem_get_sg_table, which should only be called when
> exporting, same for the pin/unpin functions, on which it relies to
> work correctly.
> 
> Cc: Gerd Hoffmann <kraxel at redhat.com>
> Cc: Rob Herring <robh at kernel.org>
> Cc: Noralf Trønnes <noralf at tronnes.org>
> Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> ---
>  drivers/gpu/drm/drm_gem_shmem_helper.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
> index 117a7841e284..f7011338813e 100644
> --- a/drivers/gpu/drm/drm_gem_shmem_helper.c
> +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
> @@ -170,6 +170,8 @@ int drm_gem_shmem_get_pages(struct drm_gem_shmem_object *shmem)
>  {
>  	int ret;
>  
> +	WARN_ON(shmem->base.import_attach);
> +
>  	ret = mutex_lock_interruptible(&shmem->pages_lock);
>  	if (ret)
>  		return ret;
> @@ -225,6 +227,8 @@ int drm_gem_shmem_pin(struct drm_gem_object *obj)
>  {
>  	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
>  
> +	WARN_ON(shmem->base.import_attach);
> +

I don't understand this change. If a driver pins pages it now has to
check that the pages are not imported?


>  	return drm_gem_shmem_get_pages(shmem);
>  }
>  EXPORT_SYMBOL(drm_gem_shmem_pin);
> @@ -240,6 +244,8 @@ void drm_gem_shmem_unpin(struct drm_gem_object *obj)
>  {
>  	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
>  
> +	WARN_ON(shmem->base.import_attach);
> +
>  	drm_gem_shmem_put_pages(shmem);
>  }
>  EXPORT_SYMBOL(drm_gem_shmem_unpin);
> @@ -510,6 +516,8 @@ static void drm_gem_shmem_vm_open(struct vm_area_struct *vma)
>  	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
>  	int ret;
>  
> +	WARN_ON(shmem->base.import_attach);
> +
>  	ret = drm_gem_shmem_get_pages(shmem);
>  	WARN_ON_ONCE(ret != 0);
>  
> @@ -611,6 +619,8 @@ struct sg_table *drm_gem_shmem_get_sg_table(struct drm_gem_object *obj)
>  {
>  	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
>  
> +	WARN_ON(shmem->base.import_attach);
> +
>  	return drm_prime_pages_to_sg(shmem->pages, obj->size >> PAGE_SHIFT);
>  }
>  EXPORT_SYMBOL_GPL(drm_gem_shmem_get_sg_table);
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer

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