[PATCH 02/26] dma-buf: add dma_resv_for_each_fence

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

A simpler version of the iterator to be used when the dma_resv object is
locked.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/dma-buf/dma-resv.c | 37 +++++++++++++++++++++++++++++++++++++
 include/linux/dma-resv.h   | 18 ++++++++++++++++++
 2 files changed, 55 insertions(+)

diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index 77083170ec3b..bbf36a08ced0 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -323,6 +323,43 @@ void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence)
 }
 EXPORT_SYMBOL(dma_resv_add_excl_fence);
 
+/**
+ * dma_resv_walk - walk over fences in a dma_resv obj
+ * @obj: the dma_resv object
+ * @cursor: cursor to record the current position
+ * @all_fences: true returns also the shared fences
+ * @first: if we should start over
+ *
+ * Return all the fences in the dma_resv object while holding the
+ * dma_resv::lock.
+ */
+struct dma_fence *dma_resv_walk(struct dma_resv *obj,
+				struct dma_resv_iter *cursor,
+				bool all_fences, bool first)
+{
+	dma_resv_assert_held(obj);
+
+	cursor->is_first = first;
+	if (first) {
+		struct dma_fence *fence;
+
+		cursor->index = -1;
+		cursor->fences = dma_resv_shared_list(obj);
+
+		fence = dma_resv_excl_fence(obj);
+		if (fence)
+			return fence;
+	}
+
+	if (!all_fences || !cursor->fences ||
+	    ++cursor->index >= cursor->fences->shared_count)
+		return NULL;
+
+	return rcu_dereference_protected(cursor->fences->shared[cursor->index],
+					 dma_resv_held(obj));
+}
+EXPORT_SYMBOL_GPL(dma_resv_walk);
+
 /**
  * dma_resv_walk_unlocked - walk over fences in a dma_resv obj
  * @obj: the dma_resv object
diff --git a/include/linux/dma-resv.h b/include/linux/dma-resv.h
index 1cd686384c71..6761512ba662 100644
--- a/include/linux/dma-resv.h
+++ b/include/linux/dma-resv.h
@@ -168,6 +168,21 @@ struct dma_resv_iter {
 	bool is_first;
 };
 
+/**
+ * dma_resv_for_each_fence - fence iterator
+ * @obj: a dma_resv object pointer
+ * @cursor: a struct dma_resv_iter pointer
+ * @all_fences: true if all fences should be returned
+ * @fence: the current fence
+ *
+ * Iterate over the fences in a struct dma_resv object while holding the
+ * dma_resv::lock. @all_fences controls if the shared fences are returned as
+ * well.
+ */
+#define dma_resv_for_each_fence(obj, cursor, all_fences, fence)		  \
+	for (fence = dma_resv_walk(obj, cursor, all_fences, true); fence; \
+	     fence = dma_resv_walk(obj, cursor, all_fences, false))
+
 /**
  * dma_resv_for_each_fence_unlocked - fence iterator
  * @obj: a dma_resv object pointer
@@ -413,6 +428,9 @@ void dma_resv_fini(struct dma_resv *obj);
 int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences);
 void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence);
 void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence);
+struct dma_fence *dma_resv_walk(struct dma_resv *obj,
+				struct dma_resv_iter *cursor,
+				bool first, bool all_fences);
 struct dma_fence *dma_resv_walk_unlocked(struct dma_resv *obj,
 					 struct dma_resv_iter *cursor,
 					 bool first, bool all_fences);
-- 
2.25.1