[RFC PATCH 1/3] drm/virtio: .release ops for virtgpu fence release

[Dmitry Osipenko]

On 8/16/23 21:10, Kim, Dongwon wrote:
> Hi,
> 
> On 8/14/2023 9:18 PM, Dmitry Osipenko wrote:
>> On 7/13/23 01:44, Dongwon Kim wrote:
>>> virtio_gpu_fence_release is added to free virtio-gpu-fence
>>> upon release of dma_fence.
>>>
>>> Cc: Gerd Hoffmann <kraxel at redhat.com>
>>> Cc: Vivek Kasireddy <vivek.kasireddy at intel.com>
>>> Signed-off-by: Dongwon Kim <dongwon.kim at intel.com>
>>> ---
>>>   drivers/gpu/drm/virtio/virtgpu_fence.c | 8 ++++++++
>>>   1 file changed, 8 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/virtio/virtgpu_fence.c
>>> b/drivers/gpu/drm/virtio/virtgpu_fence.c
>>> index f28357dbde35..ba659ac2a51d 100644
>>> --- a/drivers/gpu/drm/virtio/virtgpu_fence.c
>>> +++ b/drivers/gpu/drm/virtio/virtgpu_fence.c
>>> @@ -63,12 +63,20 @@ static void virtio_gpu_timeline_value_str(struct
>>> dma_fence *f, char *str,
>>>            (u64)atomic64_read(&fence->drv->last_fence_id));
>>>   }
>>>   +static void virtio_gpu_fence_release(struct dma_fence *f)
>>> +{
>>> +    struct virtio_gpu_fence *fence = to_virtio_gpu_fence(f);
>>> +
>>> +    kfree(fence);
>>> +}
>>> +
>>>   static const struct dma_fence_ops virtio_gpu_fence_ops = {
>>>       .get_driver_name     = virtio_gpu_get_driver_name,
>>>       .get_timeline_name   = virtio_gpu_get_timeline_name,
>>>       .signaled            = virtio_gpu_fence_signaled,
>>>       .fence_value_str     = virtio_gpu_fence_value_str,
>>>       .timeline_value_str  = virtio_gpu_timeline_value_str,
>>> +    .release         = virtio_gpu_fence_release,
>>>   };
>>>     struct virtio_gpu_fence *virtio_gpu_fence_alloc(struct
>>> virtio_gpu_device *vgdev,
>> This change doesn't do anything practically useful, AFAICT.
> 
> The intention of this ".release" is to free virtio_gpu_fence when the
> last dma_fence_put is done for the associated dma fence.

What makes you think that fence won't be freed otherwise? Sounds like
haven't tried to check what dma_fence_release() code does, have you?

-- 
Best regards,
Dmitry