Re: [PATCH 2/2] dma-buf: Add an API for importing sync files (v9)

On Friday, May 6th, 2022 at 20:02, Jason Ekstrand jason@jlekstrand.net wrote:

diff --git a/include/uapi/linux/dma-buf.h b/include/uapi/linux/dma-buf.h index 46f1e3e98b02..70e213a0d7d9 100644 --- a/include/uapi/linux/dma-buf.h +++ b/include/uapi/linux/dma-buf.h @@ -96,6 +96,24 @@ struct dma_buf_sync {

• dma-buf for waiting later instead of waiting immediately. This is
• useful for modern graphics APIs such as Vulkan which assume an explicit
• synchronization model but still need to inter-operate with dma-buf.

• • The intended usage pattern is the following:
• • 1. Export a sync_file with flags corresponding to the expected GPU usage

• • via DMA_BUF_IOCTL_EXPORT_SYNC_FILE.
    

• • 2. Submit rendering work which uses the dma-buf. The work should wait on

• • the exported sync file before rendering and produce another sync_file
    

• • when complete.
    

• • 3. Import the rendering-complete sync_file into the dma-buf with flags

• • corresponding to the GPU usage via DMA_BUF_IOCTL_EXPORT_SYNC_FILE.
    

This should read DMA_BUF_IOCTL_IMPORT_SYNC_FILE I think?

• • Unlike doing implicit synchronization via a GPU kernel driver's exec ioctl,
• • the above is not a single atomic operation. If userspace wants to ensure
• • ordering via these fences, it is the respnosibility of userspace to use
• • locks or other mechanisms to ensure that no other context adds fences or
• • submits work between steps 1 and 3 above.
  */

struct dma_buf_export_sync_file { /**