Re: [PATCH 1/3] dma-buf: make the flags can be configured during dma fence init

["Christian König" <christian.koenig@amd.com>]

Am 13.12.21 um 07:34 schrieb Huang Rui:
> In some user scenarios, the get_timeline_name callback uses the flags to
> decide which way to return the timeline string name. Once the
> trace_dma_fence_init event is enabled, it will call get_timeline_name
> callback to dump the fence structure. However, at this moment, the flags
> are always 0, and it might trigger some issues in get_timeline_name
> callback implementation of different gpu driver. So make a member to
> initialize the flags in dma_fence_init().

Well that doesn't make much sense to me.

None of the dma_fence callbacks is called from the dma_fence_init 
function (or at least shouldn't). So drivers always have the opportunity 
to to adjust the flags.

So please explain the rational again?

Christian.

>
> Signed-off-by: Huang Rui <ray.huang@amd.com>
> ---
>   drivers/dma-buf/dma-fence.c | 2 +-
>   include/linux/dma-fence.h   | 7 +++++++
>   2 files changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
> index 066400ed8841..3e0622bf385f 100644
> --- a/drivers/dma-buf/dma-fence.c
> +++ b/drivers/dma-buf/dma-fence.c
> @@ -952,7 +952,7 @@ dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
>   	fence->lock = lock;
>   	fence->context = context;
>   	fence->seqno = seqno;
> -	fence->flags = 0UL;
> +	fence->flags = ops->init_flags;
>   	fence->error = 0;
>   
>   	trace_dma_fence_init(fence);
> diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h
> index 1ea691753bd3..f9270c5bc07a 100644
> --- a/include/linux/dma-fence.h
> +++ b/include/linux/dma-fence.h
> @@ -131,6 +131,13 @@ struct dma_fence_ops {
>   	 */
>   	bool use_64bit_seqno;
>   
> +	/**
> +	 * @init_flags:
> +	 *
> +	 * The initial value of fence flags (A mask of DMA_FENCE_FLAG_* defined).
> +	 */
> +	unsigned long init_flags;
> +
>   	/**
>   	 * @get_driver_name:
>   	 *