rbtree: add RB_DECLARE_CALLBACKS() macro

As proposed by Peter Zijlstra, this makes it easier to define the augmented
rbtree callbacks.

Signed-off-by: Michel Lespinasse <walken@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 30 insertions, 0 deletions

diff --git a/include/linux/rbtree.h b/include/linux/rbtree.h
index 4ace31b33380..8d1e83b1c87b 100644
--- a/include/linux/rbtree.h
+++ b/include/linux/rbtree.h
@@ -79,6 +79,36 @@ rb_insert_augmented(struct rb_node *node, struct rb_root *root,
         __rb_insert_augmented(node, root, augment->rotate);
 }
 
+#define RB_DECLARE_CALLBACKS(rbstatic, rbname, rbstruct, rbfield,             \
+                             rbtype, rbaugmented, rbcompute)                  \
+static void rbname ## _propagate(struct rb_node *rb, struct rb_node *stop)    \
+{                                                                             \
+        while (rb != stop) {                                                  \
+                rbstruct *node = rb_entry(rb, rbstruct, rbfield);             \
+                rbtype augmented = rbcompute(node);                           \
+                if (node->rbaugmented == augmented)                           \
+                        break;                                                \
+                node->rbaugmented = augmented;                                \
+                rb = rb_parent(&node->rbfield);                               \
+        }                                                                     \
+}                                                                             \
+static void rbname ## _copy(struct rb_node *rb_old, struct rb_node *rb_new)   \
+{                                                                             \
+        rbstruct *old = rb_entry(rb_old, rbstruct, rbfield);                  \
+        rbstruct *new = rb_entry(rb_new, rbstruct, rbfield);                  \
+        new->rbaugmented = old->rbaugmented;                                  \
+}                                                                             \
+static void rbname ## _rotate(struct rb_node *rb_old, struct rb_node *rb_new) \
+{                                                                             \
+        rbstruct *old = rb_entry(rb_old, rbstruct, rbfield);                  \
+        rbstruct *new = rb_entry(rb_new, rbstruct, rbfield);                  \
+        new->rbaugmented = old->rbaugmented;                                  \
+        old->rbaugmented = rbcompute(old);                                    \
+}                                                                             \
+rbstatic const struct rb_augment_callbacks rbname = {                         \
+        rbname ## _propagate, rbname ## _copy, rbname ## _rotate              \
+};
+
 
 /* Find logical next and previous nodes in a tree */
 extern struct rb_node *rb_next(const struct rb_node *);