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From:   Chia-I Wu <olvaffe@gmail.com>
Date:   Wed, 26 Jun 2019 17:49:06 -0700
Message-ID: <CAPaKu7RwVC3p=K0gxy=NfJaCJd_RkRc1vCKH4e7oS8rn-6wyOQ@mail.gmail.com>
Subject: Re: [PATCH v4 07/12] drm/virtio: add virtio_gpu_object_array & helpers
To:     Gerd Hoffmann <kraxel@redhat.com>
Cc:     ML dri-devel <dri-devel@lists.freedesktop.org>,
        David Airlie <airlied@linux.ie>,
        open list <linux-kernel@vger.kernel.org>,
        "open list:VIRTIO GPU DRIVER" 
        <virtualization@lists.linux-foundation.org>
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On Wed, Jun 19, 2019 at 11:08 PM Gerd Hoffmann <kraxel@redhat.com> wrote:
>
> Some helper functions to manage an array of gem objects.
>
> v4: make them virtio-private instead of generic helpers.
>
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
>  drivers/gpu/drm/virtio/virtgpu_drv.h | 10 ++++++
>  drivers/gpu/drm/virtio/virtgpu_gem.c | 50 ++++++++++++++++++++++++++++
>  2 files changed, 60 insertions(+)
>
> diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h b/drivers/gpu/drm/virtio/virtgpu_drv.h
> index 07f6001ea91e..98d646789d23 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_drv.h
> +++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
> @@ -84,6 +84,11 @@ struct virtio_gpu_object {
>  #define gem_to_virtio_gpu_obj(gobj) \
>         container_of((gobj), struct virtio_gpu_object, gem_base)
>
> +struct virtio_gpu_object_array {
> +       u32 nents;
> +       struct drm_gem_object *objs[];
> +};
> +
>  struct virtio_gpu_vbuffer;
>  struct virtio_gpu_device;
>
> @@ -251,6 +256,11 @@ int virtio_gpu_mode_dumb_mmap(struct drm_file *file_priv,
>                               struct drm_device *dev,
>                               uint32_t handle, uint64_t *offset_p);
>
> +struct virtio_gpu_object_array *virtio_gpu_array_alloc(u32 nents);
> +struct virtio_gpu_object_array*
> +virtio_gpu_array_from_handles(struct drm_file *drm_file, u32 *handles, u32 nents);
> +void virtio_gpu_array_put_free(struct virtio_gpu_object_array *objs);
> +
>  /* virtio vg */
>  int virtio_gpu_alloc_vbufs(struct virtio_gpu_device *vgdev);
>  void virtio_gpu_free_vbufs(struct virtio_gpu_device *vgdev);
> diff --git a/drivers/gpu/drm/virtio/virtgpu_gem.c b/drivers/gpu/drm/virtio/virtgpu_gem.c
> index 9c9ad3b14080..456cc382ce68 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_gem.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_gem.c
> @@ -169,3 +169,53 @@ void virtio_gpu_gem_object_close(struct drm_gem_object *obj,
>                                                 qobj->hw_res_handle);
>         virtio_gpu_object_unreserve(qobj);
>  }
> +
> +struct virtio_gpu_object_array *virtio_gpu_array_alloc(u32 nents)
> +{
> +       struct virtio_gpu_object_array *objs;
> +       size_t size = sizeof(*objs) + sizeof(objs->objs[0]) * nents;
> +
> +       objs = kzalloc(size, GFP_KERNEL);
It seems unlikely to get wrong.  Use kmalloc instead?
> +       if (!objs)
> +               return NULL;
> +
> +       objs->nents = nents;
> +       return objs;
> +}
> +
> +static void virtio_gpu_array_free(struct virtio_gpu_object_array *objs)
> +{
> +       kfree(objs);
> +}
> +
> +struct virtio_gpu_object_array*
> +virtio_gpu_array_from_handles(struct drm_file *drm_file, u32 *handles, u32 nents)
> +{
> +       struct virtio_gpu_object_array *objs;
> +       u32 i;
> +
> +       objs = virtio_gpu_array_alloc(nents);
> +       if (!objs)
> +               return NULL;
> +
> +       for (i = 0; i < nents; i++) {
> +               objs->objs[i] = drm_gem_object_lookup(drm_file, handles[i]);
> +               if (!objs->objs[i]) {
> +                       virtio_gpu_array_put_free(objs);
Set objs->nents to i before calling i915_gem_object_lookup;
> +                       return NULL;
Should we distinguish ENOMEM and ENOENT?
> +               }
> +       }
> +       return objs;
> +}
> +
> +void virtio_gpu_array_put_free(struct virtio_gpu_object_array *objs)
> +{
> +       u32 i;
> +
> +       for (i = 0; i < objs->nents; i++) {
> +               if (!objs->objs[i])
> +                       continue;
The check can be removed if the change in virtio_gpu_array_from_handles.
> +               drm_gem_object_put_unlocked(objs->objs[i]);
> +       }
> +       virtio_gpu_array_free(objs);
> +}
> --
> 2.18.1
>
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