Re: [PATCH v6] drm/syncobj: Extend EXPORT_SYNC_FILE for timeline syncobjs

[Dmitry Osipenko <dmitry.osipenko@collabora.com>]

On 4/1/25 23:40, Rob Clark wrote:
> On Tue, Apr 1, 2025 at 8:58 AM Rob Clark <robdclark@gmail.com> wrote:
>>
>> From: Rob Clark <robdclark@chromium.org>
>>
>> Add support for exporting a dma_fence fd for a specific point on a
>> timeline.  This is needed for vtest/vpipe[1][2] to implement timeline
>> syncobj support, as it needs a way to turn a point on a timeline back
>> into a dma_fence fd.  It also closes an odd omission from the syncobj
>> UAPI.
>>
>> [1] https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/33433
>> [2] https://gitlab.freedesktop.org/virgl/virglrenderer/-/merge_requests/805
>>
>> v2: Add DRM_SYNCOBJ_HANDLE_TO_FD_FLAGS_TIMELINE
>> v3: Add unstaged uabi header hunk
>> v4: Also handle IMPORT_SYNC_FILE case
>> v5: Address comments from Dmitry
>> v6: checkpatch.pl nits
>>
>> Signed-off-by: Rob Clark <robdclark@chromium.org>
>> Reviewed-by: Christian König <christian.koenig@amd.com>
>> Reviewed-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
>> ---
>>  drivers/gpu/drm/drm_syncobj.c | 47 +++++++++++++++++++++++++++--------
>>  include/uapi/drm/drm.h        |  4 +++
>>  2 files changed, 41 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
>> index 4f2ab8a7b50f..636cd83ca29e 100644
>> --- a/drivers/gpu/drm/drm_syncobj.c
>> +++ b/drivers/gpu/drm/drm_syncobj.c
>> @@ -741,7 +741,7 @@ static int drm_syncobj_fd_to_handle(struct drm_file *file_private,
>>  }
>>
>>  static int drm_syncobj_import_sync_file_fence(struct drm_file *file_private,
>> -                                             int fd, int handle)
>> +                                             int fd, int handle, u64 point)
>>  {
>>         struct dma_fence *fence = sync_file_get_fence(fd);
>>         struct drm_syncobj *syncobj;
>> @@ -755,14 +755,24 @@ static int drm_syncobj_import_sync_file_fence(struct drm_file *file_private,
>>                 return -ENOENT;
>>         }
>>
>> -       drm_syncobj_replace_fence(syncobj, fence);
>> +       if (point) {
>> +               struct dma_fence_chain *chain = dma_fence_chain_alloc();
>> +
>> +               if (!chain)
>> +                       return -ENOMEM;
>> +
>> +               drm_syncobj_add_point(syncobj, chain, fence, point);
>> +       } else {
>> +               drm_syncobj_replace_fence(syncobj, fence);
>> +       }
>> +
>>         dma_fence_put(fence);
>>         drm_syncobj_put(syncobj);
>>         return 0;
>>  }
>>
>>  static int drm_syncobj_export_sync_file(struct drm_file *file_private,
>> -                                       int handle, int *p_fd)
>> +                                       int handle, u64 point, int *p_fd)
>>  {
>>         int ret;
>>         struct dma_fence *fence;
>> @@ -772,7 +782,7 @@ static int drm_syncobj_export_sync_file(struct drm_file *file_private,
>>         if (fd < 0)
>>                 return fd;
>>
>> -       ret = drm_syncobj_find_fence(file_private, handle, 0, 0, &fence);
>> +       ret = drm_syncobj_find_fence(file_private, handle, point, 0, &fence);
>>         if (ret)
>>                 goto err_put_fd;
>>
>> @@ -869,6 +879,9 @@ drm_syncobj_handle_to_fd_ioctl(struct drm_device *dev, void *data,
>>                                    struct drm_file *file_private)
>>  {
>>         struct drm_syncobj_handle *args = data;
>> +       unsigned int valid_flags = DRM_SYNCOBJ_HANDLE_TO_FD_FLAGS_TIMELINE |
>> +                                  DRM_SYNCOBJ_HANDLE_TO_FD_FLAGS_EXPORT_SYNC_FILE;
>> +       u64 point = 0;
>>
>>         if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ))
>>                 return -EOPNOTSUPP;
>> @@ -876,13 +889,18 @@ drm_syncobj_handle_to_fd_ioctl(struct drm_device *dev, void *data,
>>         if (args->pad)
>>                 return -EINVAL;
>>
>> -       if (args->flags != 0 &&
>> -           args->flags != DRM_SYNCOBJ_HANDLE_TO_FD_FLAGS_EXPORT_SYNC_FILE)
>> +       if (args->flags & ~valid_flags)
>>                 return -EINVAL;
>>
>> +       if (args->flags & DRM_SYNCOBJ_HANDLE_TO_FD_FLAGS_TIMELINE)
>> +               point = args->point;
>> +
>>         if (args->flags & DRM_SYNCOBJ_HANDLE_TO_FD_FLAGS_EXPORT_SYNC_FILE)
>>                 return drm_syncobj_export_sync_file(file_private, args->handle,
>> -                                                   &args->fd);
>> +                                                   point, &args->fd);
>> +
>> +       if (args->point)
>> +               return -EINVAL;
>>
>>         return drm_syncobj_handle_to_fd(file_private, args->handle,
>>                                         &args->fd);
>> @@ -893,6 +911,9 @@ drm_syncobj_fd_to_handle_ioctl(struct drm_device *dev, void *data,
>>                                    struct drm_file *file_private)
>>  {
>>         struct drm_syncobj_handle *args = data;
>> +       unsigned int valid_flags = DRM_SYNCOBJ_FD_TO_HANDLE_FLAGS_TIMELINE |
>> +                                  DRM_SYNCOBJ_FD_TO_HANDLE_FLAGS_IMPORT_SYNC_FILE;
>> +       u64 point = 0;
>>
>>         if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ))
>>                 return -EOPNOTSUPP;
> 
> oh, I suppose I should add a check for DRIVER_SYNCOBJ_TIMELINE?  I'll
> send a v7 a bit later

Christian already applied to misc-test, please rebase and make it as a
new patch

-- 
Best regards,
Dmitry