We clear the callback list on kref_put so that by the time we
release the fence it is unused. No one should be adding to the cb_list
that they don't themselves hold a reference for.
This small change is actually making the structure 16% smaller.
v2: add the comment to the code as well.
Signed-off-by: Christian König <christian.koenig@xxxxxxx>
Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
include/linux/dma-fence.h | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h
index 05d29dbc7e62..bea1d05cf51e 100644
--- a/include/linux/dma-fence.h
+++ b/include/linux/dma-fence.h
@@ -65,8 +65,14 @@ struct dma_fence_cb;
struct dma_fence {
struct kref refcount;
const struct dma_fence_ops *ops;
- struct rcu_head rcu;
- struct list_head cb_list;
+ /* We clear the callback list on kref_put so that by the time we
+ * release the fence it is unused. No one should be adding to the cb_list
+ * that they don't themselves hold a reference for.
+ */
+ union {
+ struct rcu_head rcu;
+ struct list_head cb_list;
+ };
spinlock_t *lock;
u64 context;
u64 seqno;
--
2.17.1
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