[PATCH 5.17 0183/1126] drm/syncobj: flatten dma_fence_chains on transfer

Greg Kroah-Hartman
2022-04-05T07:50:58Z

From: Christian König <christian.koenig@amd.com>

commit 721255b52700b320c4ae2e23d57f7d9ad1db50b9 upstream.

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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/gpu/drm/drm_syncobj.c | 61 ++++++++++++++++++++++++++++++++++++++----
1 file changed, 56 insertions(+), 5 deletions(-)

--- 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 dr
&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_timel
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;