drm/syncobj: flatten dma_fence_chains on transfer

It is illegal to add a dma_fence_chain as timeline point. Flatten out
the fences into a dma_fence_array instead.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Nirmoy Das <nirmoy.das@linux.intel.com>
Cc: <stable@vger.kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220209182600.434803-1-christian.koenig@amd.com

diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
index c313a5b..7e48dcd 100644 (file)
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -853,12 +853,57 @@ drm_syncobj_fd_to_handle_ioctl(struct drm_device *dev, void *data,
                                        &args->handle);
 }
 
+
+/*
+ * Try to flatten a dma_fence_chain into a dma_fence_array so that it can be
+ * added as timeline fence to a chain again.
+ */
+static int drm_syncobj_flatten_chain(struct dma_fence **f)
+{
+       struct dma_fence_chain *chain = to_dma_fence_chain(*f);
+       struct dma_fence *tmp, **fences;
+       struct dma_fence_array *array;
+       unsigned int count;
+
+       if (!chain)
+               return 0;
+
+       count = 0;
+       dma_fence_chain_for_each(tmp, &chain->base)
+               ++count;
+
+       fences = kmalloc_array(count, sizeof(*fences), GFP_KERNEL);
+       if (!fences)
+               return -ENOMEM;
+
+       count = 0;
+       dma_fence_chain_for_each(tmp, &chain->base)
+               fences[count++] = dma_fence_get(tmp);
+
+       array = dma_fence_array_create(count, fences,
+                                      dma_fence_context_alloc(1),
+                                      1, false);
+       if (!array)
+               goto free_fences;
+
+       dma_fence_put(*f);
+       *f = &array->base;
+       return 0;
+
+free_fences:
+       while (count--)
+               dma_fence_put(fences[count]);
+
+       kfree(fences);
+       return -ENOMEM;
+}
+
 static int drm_syncobj_transfer_to_timeline(struct drm_file *file_private,
                                            struct drm_syncobj_transfer *args)
 {
        struct drm_syncobj *timeline_syncobj = NULL;
-       struct dma_fence *fence;
        struct dma_fence_chain *chain;
+       struct dma_fence *fence;
        int ret;
 
        timeline_syncobj = drm_syncobj_find(file_private, args->dst_handle);
@@ -869,16 +914,22 @@ static int drm_syncobj_transfer_to_timeline(struct drm_file *file_private,
                                     args->src_point, args->flags,
                                     &fence);
        if (ret)
-               goto err;
+               goto err_put_timeline;
+
+       ret = drm_syncobj_flatten_chain(&fence);
+       if (ret)
+               goto err_free_fence;
+
        chain = dma_fence_chain_alloc();
        if (!chain) {
                ret = -ENOMEM;
-               goto err1;
+               goto err_free_fence;
        }
+
        drm_syncobj_add_point(timeline_syncobj, chain, fence, args->dst_point);
-err1:
+err_free_fence:
        dma_fence_put(fence);
-err:
+err_put_timeline:
        drm_syncobj_put(timeline_syncobj);
 
        return ret;