[PATCH 1/5] drm/prime: fix potential race in drm_gem_map_detach

[Christian König]

Ping? Anybody who could give me an review on those changes?

The first one is just nice to have, the rest is a nice memory usage 
reduction in some cases.

Christian.

Am 27.02.2018 um 12:49 schrieb Christian König:
> Unpin the GEM object only after freeing the sg table.
>
> Signed-off-by: Christian König <christian.koenig at amd.com>
> ---
>   drivers/gpu/drm/drm_prime.c | 32 ++++++++++++++++----------------
>   1 file changed, 16 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
> index e82a976f0fba..c38dacda6119 100644
> --- a/drivers/gpu/drm/drm_prime.c
> +++ b/drivers/gpu/drm/drm_prime.c
> @@ -230,26 +230,26 @@ void drm_gem_map_detach(struct dma_buf *dma_buf,
>   	struct drm_prime_attachment *prime_attach = attach->priv;
>   	struct drm_gem_object *obj = dma_buf->priv;
>   	struct drm_device *dev = obj->dev;
> -	struct sg_table *sgt;
>   
> -	if (dev->driver->gem_prime_unpin)
> -		dev->driver->gem_prime_unpin(obj);
> +	if (prime_attach) {
> +		struct sg_table *sgt = prime_attach->sgt;
>   
> -	if (!prime_attach)
> -		return;
> -
> -	sgt = prime_attach->sgt;
> -	if (sgt) {
> -		if (prime_attach->dir != DMA_NONE)
> -			dma_unmap_sg_attrs(attach->dev, sgt->sgl, sgt->nents,
> -					   prime_attach->dir,
> -					   DMA_ATTR_SKIP_CPU_SYNC);
> -		sg_free_table(sgt);
> +		if (sgt) {
> +			if (prime_attach->dir != DMA_NONE)
> +				dma_unmap_sg_attrs(attach->dev, sgt->sgl,
> +						   sgt->nents,
> +						   prime_attach->dir,
> +						   DMA_ATTR_SKIP_CPU_SYNC);
> +			sg_free_table(sgt);
> +		}
> +
> +		kfree(sgt);
> +		kfree(prime_attach);
> +		attach->priv = NULL;
>   	}
>   
> -	kfree(sgt);
> -	kfree(prime_attach);
> -	attach->priv = NULL;
> +	if (dev->driver->gem_prime_unpin)
> +		dev->driver->gem_prime_unpin(obj);
>   }
>   EXPORT_SYMBOL(drm_gem_map_detach);
>