[PATCH v2 1/5] drm/exynos: iommu: move dma_params configuration code to separate functions

[Inki Dae]

Hi Marek,

2016년 06월 17일 16:54에 Marek Szyprowski 이(가) 쓴 글:
> Move code for managing DMA max segment size parameter to separate
> functions. This patch also replaces devm_kzalloc() with kzalloc() and
> adds proper kfree call. devm_kzalloc() cannot be used for dma_params
> structure, because it will be freed on driver remove not on device
> release. This means in case of Exynos DRM being compiled as module and
> loaded 2 times, a user-after-free issue will happen.

Picked this patch series up.

Thanks,
Inki Dae

> 
> Signed-off-by: Marek Szyprowski <m.szyprowski at samsung.com>
> ---
>  drivers/gpu/drm/exynos/exynos_drm_iommu.c | 28 ++++++++++++++++++++++------
>  1 file changed, 22 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_iommu.c 
> b/drivers/gpu/drm/exynos/exynos_drm_iommu.c
> index 7ca09ee19656..1e82529e0c41 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_iommu.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_iommu.c
> @@ -21,6 +21,23 @@
>  #include "exynos_drm_drv.h"
>  #include "exynos_drm_iommu.h"
>  
> +static inline int configure_dma_max_seg_size(struct device *dev)
> +{
> +     if (!dev->dma_parms)
> +             dev->dma_parms = kzalloc(sizeof(*dev->dma_parms), GFP_KERNEL);
> +     if (!dev->dma_parms)
> +             return -ENOMEM;
> +
> +     dma_set_max_seg_size(dev, DMA_BIT_MASK(32));
> +     return 0;
> +}
> +
> +static inline void clear_dma_max_seg_size(struct device *dev)
> +{
> +     kfree(dev->dma_parms);
> +     dev->dma_parms = NULL;
> +}
> +
>  /*
>   * drm_create_iommu_mapping - create a mapping structure
>   *
> @@ -80,13 +97,10 @@ int drm_iommu_attach_device(struct drm_device *drm_dev,
>       if (!priv->mapping)
>               return 0;
>  
> -     subdrv_dev->dma_parms = devm_kzalloc(subdrv_dev,
> -                                     sizeof(*subdrv_dev->dma_parms),
> -                                     GFP_KERNEL);
> -     if (!subdrv_dev->dma_parms)
> -             return -ENOMEM;
>  
> -     dma_set_max_seg_size(subdrv_dev, 0xffffffffu);
> +     ret = configure_dma_max_seg_size(subdrv_dev);
> +     if (ret)
> +             return ret;
>  
>       if (subdrv_dev->archdata.mapping)
>               arm_iommu_detach_device(subdrv_dev);
> @@ -94,6 +108,7 @@ int drm_iommu_attach_device(struct drm_device *drm_dev,
>       ret = arm_iommu_attach_device(subdrv_dev, priv->mapping);
>       if (ret < 0) {
>               DRM_DEBUG_KMS("failed iommu attach.\n");
> +             clear_dma_max_seg_size(subdrv_dev);
>               return ret;
>       }
>  
> @@ -119,4 +134,5 @@ void drm_iommu_detach_device(struct drm_device *drm_dev,
>               return;
>  
>       arm_iommu_detach_device(subdrv_dev);
> +     clear_dma_max_seg_size(subdrv_dev);
>  }
>