linux-kernel - RE: [PATCH v1] drm/virtio: Factor out common dmabuf unmapping code

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Message-ID: <CH3PR11MB7177E2E8406A00BAF210130EF8352@CH3PR11MB7177.namprd11.prod.outlook.com>
Date: Mon, 2 Dec 2024 17:37:21 +0000
From: "Kasireddy, Vivek" <vivek.kasireddy@...el.com>
To: Dmitry Osipenko <dmitry.osipenko@...labora.com>, David Airlie
	<airlied@...hat.com>, Gerd Hoffmann <kraxel@...hat.com>, Gurchetan Singh
	<gurchetansingh@...omium.org>, Chia-I Wu <olvaffe@...il.com>, "Kim, Dongwon"
	<dongwon.kim@...el.com>
CC: Rob Clark <robdclark@...il.com>, "dri-devel@...ts.freedesktop.org"
	<dri-devel@...ts.freedesktop.org>, "virtualization@...ts.linux.dev"
	<virtualization@...ts.linux.dev>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "kernel@...labora.com" <kernel@...labora.com>
Subject: RE: [PATCH v1] drm/virtio: Factor out common dmabuf unmapping code

Hi Dmitry,

> Subject: [PATCH v1] drm/virtio: Factor out common dmabuf unmapping code
> 
> Move out dmabuf detachment and unmapping into separate function. This
> removes duplicated code and there is no need to check the GEM's kref now,
> since both bo->attached and bo->sgt are unset under held reservation lock.
> 
> Signed-off-by: Dmitry Osipenko <dmitry.osipenko@...labora.com>
> ---
>  drivers/gpu/drm/virtio/virtgpu_prime.c | 35 ++++++++++++++------------
>  1 file changed, 19 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/gpu/drm/virtio/virtgpu_prime.c
> b/drivers/gpu/drm/virtio/virtgpu_prime.c
> index 33084ce1d01d..101d1a6517ae 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_prime.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_prime.c
> @@ -184,22 +184,33 @@ int virtgpu_dma_buf_import_sgt(struct
> virtio_gpu_mem_entry **ents,
>  	return 0;
>  }
> 
> -static void virtgpu_dma_buf_free_obj(struct drm_gem_object *obj)
> +static void virtgpu_dma_buf_unmap(struct virtio_gpu_object *bo)
>  {
> -	struct virtio_gpu_object *bo = gem_to_virtio_gpu_obj(obj);
> -	struct virtio_gpu_device *vgdev = obj->dev->dev_private;
> -	struct dma_buf_attachment *attach = obj->import_attach;
> -	struct dma_resv *resv = attach->dmabuf->resv;
> +	struct dma_buf_attachment *attach = bo->base.base.import_attach;
> 
> -	if (attach) {
> -		dma_resv_lock(resv, NULL);
> +	dma_resv_assert_held(attach->dmabuf->resv);
> 
> +	if (bo->created) {
>  		virtio_gpu_detach_object_fenced(bo);
> 
>  		if (bo->sgt)
>  			dma_buf_unmap_attachment(attach, bo->sgt,
>  						 DMA_BIDIRECTIONAL);
> 
> +		bo->sgt = NULL;
> +	}
> +}
> +
> +static void virtgpu_dma_buf_free_obj(struct drm_gem_object *obj)
> +{
> +	struct virtio_gpu_object *bo = gem_to_virtio_gpu_obj(obj);
> +	struct virtio_gpu_device *vgdev = obj->dev->dev_private;
> +	struct dma_buf_attachment *attach = obj->import_attach;
> +	struct dma_resv *resv = attach->dmabuf->resv;
> +
> +	if (attach) {
> +		dma_resv_lock(resv, NULL);
> +		virtgpu_dma_buf_unmap(bo);
>  		dma_resv_unlock(resv);
> 
>  		dma_buf_detach(attach->dmabuf, attach);
> @@ -272,15 +283,7 @@ static void virtgpu_dma_buf_move_notify(struct
> dma_buf_attachment *attach)
>  	struct drm_gem_object *obj = attach->importer_priv;
>  	struct virtio_gpu_object *bo = gem_to_virtio_gpu_obj(obj);
> 
> -	if (bo->created && kref_read(&obj->refcount)) {
> -		virtio_gpu_detach_object_fenced(bo);
> -
> -		if (bo->sgt)
> -			dma_buf_unmap_attachment(attach, bo->sgt,
> -						 DMA_BIDIRECTIONAL);
> -
> -		bo->sgt = NULL;
> -	}
> +	virtgpu_dma_buf_unmap(bo);
LGTM.
Acked-by: Vivek Kasireddy <vivek.kasireddy@...el.com>

>  }
> 
>  static const struct dma_buf_attach_ops virtgpu_dma_buf_attach_ops = {
> --
> 2.47.0
>