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

[Christian König]

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

Signed-off-by: Christian König <christian.koenig at amd.com>
---
 drivers/dma-buf/dma-resv.c | 33 +++++++++++++++++++++++++++++++++
 include/linux/dma-resv.h   | 17 +++++++++++++++++
 2 files changed, 50 insertions(+)

diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index 3e77cad2c9d4..a3c79a99fb44 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -384,6 +384,39 @@ struct dma_fence *dma_resv_iter_walk_unlocked(struct dma_resv_iter *cursor,
 }
 EXPORT_SYMBOL_GPL(dma_resv_iter_walk_unlocked);
 
+/**
+ * dma_resv_iter_walk - walk over fences in a dma_resv obj
+ * @cursor: cursor to record the current position
+ * @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_iter_walk(struct dma_resv_iter *cursor, bool first)
+{
+	dma_resv_assert_held(cursor->obj);
+
+	cursor->is_first = first;
+	if (first) {
+		struct dma_fence *fence;
+
+		cursor->index = -1;
+		cursor->fences = dma_resv_shared_list(cursor->obj);
+
+		fence = dma_resv_excl_fence(cursor->obj);
+		if (fence)
+			return fence;
+	}
+
+	if (!cursor->all_fences || !cursor->fences ||
+	    ++cursor->index >= cursor->fences->shared_count)
+		return NULL;
+
+	return rcu_dereference_protected(cursor->fences->shared[cursor->index],
+					 dma_resv_held(cursor->obj));
+}
+EXPORT_SYMBOL_GPL(dma_resv_iter_walk);
+
 /**
  * dma_resv_copy_fences - Copy all fences from src to dst.
  * @dst: the destination reservation object
diff --git a/include/linux/dma-resv.h b/include/linux/dma-resv.h
index 693d16117153..8c968f8c9d33 100644
--- a/include/linux/dma-resv.h
+++ b/include/linux/dma-resv.h
@@ -179,6 +179,7 @@ struct dma_resv_iter {
 
 struct dma_fence *dma_resv_iter_walk_unlocked(struct dma_resv_iter *cursor,
 					      bool first);
+struct dma_fence *dma_resv_iter_walk(struct dma_resv_iter *cursor, bool first);
 
 /**
  * dma_resv_iter_begin - initialize a dma_resv_iter object
@@ -233,6 +234,22 @@ static inline bool dma_resv_iter_is_exclusive(struct dma_resv_iter *cursor)
 	for (fence = dma_resv_iter_walk_unlocked(cursor, true);		\
 	     fence; fence = dma_resv_iter_walk_unlocked(cursor, false))
 
+/**
+ * dma_resv_for_each_fence - fence iterator
+ * @cursor: a struct dma_resv_iter pointer
+ * @obj: a dma_resv object 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. The cursor initialisation is part of the iterator.
+ */
+#define dma_resv_for_each_fence(cursor, obj, all_fences, fence)	\
+	for (dma_resv_iter_begin(cursor, obj, all_fences),	\
+	     fence = dma_resv_iter_walk(cursor, true); fence;	\
+	     fence = dma_resv_iter_walk(cursor, false))
+
 #define dma_resv_held(obj) lockdep_is_held(&(obj)->lock.base)
 #define dma_resv_assert_held(obj) lockdep_assert_held(&(obj)->lock.base)
 
-- 
2.25.1