A sync_file exported from a timeline point can contain a dma_fence_chain.
Importing such a sync_file into a timeline point with
DRM_SYNCOBJ_FD_TO_HANDLE_FLAGS_IMPORT_SYNC_FILE |
DRM_SYNCOBJ_FD_TO_HANDLE_FLAGS_TIMELINE passes the chain directly to
dma_fence_chain_init() and triggers
WARNING: drivers/dma-buf/dma-fence-chain.c:286 at dma_fence_chain_init
because chain fences must not be wrapped in other chain fences.
Flatten the fence with dma_fence_unwrap_merge() before adding it to the
timeline, as drm_syncobj_transfer_to_timeline() already does.
Reproducer:
1. Export a sync_file from a point > 0 of a timeline syncobj with
DRM_IOCTL_SYNCOBJ_HANDLE_TO_FD.
2. Import it into a point > 0 of another timeline syncobj with
DRM_IOCTL_SYNCOBJ_FD_TO_HANDLE.
Fixes: c2d3a7300695 ("drm/syncobj: Extend EXPORT_SYNC_FILE for timeline
syncobjs")
Assisted-by: Claude:claude-opus-5-5
Signed-off-by: Julian Orth <[email protected]>
---
drivers/gpu/drm/drm_syncobj.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
index 5ca5163d0..c545af77e 100644
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -742,8 +742,18 @@ static int drm_syncobj_import_sync_file_fence(struct
drm_file *file_private,
}
if (point) {
- struct dma_fence_chain *chain = dma_fence_chain_alloc();
+ struct dma_fence_chain *chain;
+ struct dma_fence *tmp;
+
+ tmp = dma_fence_unwrap_merge(fence);
+ dma_fence_put(fence);
+ fence = tmp;
+ if (!fence) {
+ drm_syncobj_put(syncobj);
+ return -ENOMEM;
+ }
+ chain = dma_fence_chain_alloc();
if (!chain) {
ret = -ENOMEM;
goto out;
--
2.56.0
