Merge tag 'v6.6-rc7' into core

Linux 6.6-rc7

1 files changed, 19 insertions, 0 deletions

diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h
index 0d678e9a7b24..ebe78bd3d121 100644
--- a/include/linux/dma-fence.h
+++ b/include/linux/dma-fence.h
@@ -568,6 +568,25 @@ static inline void dma_fence_set_error(struct dma_fence *fence,
 	fence->error = error;
 }
 
+/**
+ * dma_fence_timestamp - helper to get the completion timestamp of a fence
+ * @fence: fence to get the timestamp from.
+ *
+ * After a fence is signaled the timestamp is updated with the signaling time,
+ * but setting the timestamp can race with tasks waiting for the signaling. This
+ * helper busy waits for the correct timestamp to appear.
+ */
+static inline ktime_t dma_fence_timestamp(struct dma_fence *fence)
+{
+	if (WARN_ON(!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)))
+		return ktime_get();
+
+	while (!test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags))
+		cpu_relax();
+
+	return fence->timestamp;
+}
+
 signed long dma_fence_wait_timeout(struct dma_fence *,
 				   bool intr, signed long timeout);
 signed long dma_fence_wait_any_timeout(struct dma_fence **fences,