[PATCH] backports: add rb_tree_cached

From: Johannes Berg <[email protected]>

We just map them to the normal rb_tree, losing the efficiency
gain in this case.

ticket=none

Signed-off-by: Johannes Berg <[email protected]>
---
 backport/backport-include/linux/rbtree.h | 25 ++++++++++++++++++++++++
 patches/0104-rb-tree-cached.cocci        |  5 +++++
 2 files changed, 30 insertions(+)
 create mode 100644 backport/backport-include/linux/rbtree.h
 create mode 100644 patches/0104-rb-tree-cached.cocci

diff --git a/backport/backport-include/linux/rbtree.h b/backport/backport-include/linux/rbtree.h
new file mode 100644
index 000000000000..feccff36e7dd
--- /dev/null
+++ b/backport/backport-include/linux/rbtree.h
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2021 Intel Corporation
+ */
+#ifndef __BACKPORT_RBTREE_H
+#define __BACKPORT_RBTREE_H
+#include_next <linux/rbtree.h>
+
+#if LINUX_VERSION_IS_LESS(4,14,0)
+#define rb_root_cached rb_root
+#define rb_first_cached rb_first
+static inline void rb_insert_color_cached(struct rb_node *node,
+					  struct rb_root_cached *root,
+					  bool leftmost)
+{
+	rb_insert_color(node, root);
+}
+#define rb_erase_cached rb_erase
+#define RB_ROOT_CACHED RB_ROOT
+#define rb_root_node(root) (root)->rb_node
+#else
+#define rb_root_node(root) (root)->rb_root.rb_node
+#endif
+
+#endif /* __BACKPORT_RBTREE_H */
diff --git a/patches/0104-rb-tree-cached.cocci b/patches/0104-rb-tree-cached.cocci
new file mode 100644
index 000000000000..a8388c847a5a
--- /dev/null
+++ b/patches/0104-rb-tree-cached.cocci
@@ -0,0 +1,5 @@
+@@
+struct rb_root_cached *root;
+@@
+-root->rb_root.rb_node
++rb_root_node(root)
-- 
2.31.1

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