[PATCH 04/10] dma-buf: add dma_fence_array_for_each

["Christian König" <ckoenig.leichtzumerken@gmail.com>]

Makes it easier to extract the fences in a dma_fence_array.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/dma-buf/dma-fence-array.c | 42 +++++++++++++++++++++++++++++++
 include/linux/dma-fence-array.h   | 24 ++++++++++++++++++
 2 files changed, 66 insertions(+)

diff --git a/drivers/dma-buf/dma-fence-array.c b/drivers/dma-buf/dma-fence-array.c
index 314cf0e881d9..887e32e89269 100644
--- a/drivers/dma-buf/dma-fence-array.c
+++ b/drivers/dma-buf/dma-fence-array.c
@@ -265,3 +265,45 @@ bool dma_fence_match_context(struct dma_fence *fence, u64 context)
 	return true;
 }
 EXPORT_SYMBOL(dma_fence_match_context);
+
+/**
+ * dma_fence_array_first - return the first fence in an array
+ * @cursor: cursor for the current position
+ * @array: array with the fences
+ *
+ * Returns the first fence in the array or NULL if the array is empty.
+ * If the array parameter isn't a dma_fence_array return it unmodified.
+ */
+struct dma_fence *dma_fence_array_first(struct dma_fence_array_cursor *cursor,
+					struct dma_fence *array)
+{
+	cursor->array = to_dma_fence_array(array);
+	if (!cursor->array)
+		return array;
+
+	if (!cursor->array->num_fences)
+		return NULL;
+
+	cursor->index = 0;
+	return cursor->array->fences[cursor->index++];
+
+}
+EXPORT_SYMBOL(dma_fence_array_first);
+
+/**
+ * dma_fence_array_next - return the next fence in the array
+ * @cursor: cursor for the current position
+ *
+ * Returns the next fence from the array or NULL if we don't have any more
+ */
+struct dma_fence *dma_fence_array_next(struct dma_fence_array_cursor *cursor)
+{
+	if (!cursor->array)
+		return NULL;
+
+	if (cursor->index >= cursor->array->num_fences)
+		return NULL;
+
+	return cursor->array->fences[cursor->index++];
+}
+EXPORT_SYMBOL(dma_fence_array_next);
diff --git a/include/linux/dma-fence-array.h b/include/linux/dma-fence-array.h
index 35d1d1e7c93b..2a71fd003dfa 100644
--- a/include/linux/dma-fence-array.h
+++ b/include/linux/dma-fence-array.h
@@ -124,4 +124,28 @@ dma_fence_array_create(int num_fences, struct dma_fence **fences, u64 context,
 
 bool dma_fence_match_context(struct dma_fence *fence, u64 context);
 
+/**
+ * struct dma_fence_array_cursor - cursor for the fences in an array
+ */
+struct dma_fence_array_cursor {
+	struct dma_fence_array *array;
+	unsigned int index;
+};
+
+struct dma_fence *dma_fence_array_first(struct dma_fence_array_cursor *cursor,
+					struct dma_fence *array);
+struct dma_fence *dma_fence_array_next(struct dma_fence_array_cursor *cursor);
+
+/**
+ * dma_fence_array_for_each - walk over all fences in a fence array
+ * @fence: the current fence
+ * @cursor: cursor for the walk
+ * @array: potentitally fence array
+ *
+ * Walk over all the fences in the array.
+ */
+#define dma_fence_array_for_each(fence, cursor, array)		\
+	for (fence = dma_fence_array_first(&(cursor), array);	\
+	     fence; fence = dma_fence_array_next(&(cursor)))
+
 #endif /* __LINUX_DMA_FENCE_ARRAY_H */
-- 
2.17.1