[PATCH] rbtree: fixed reversed RB_EMPTY_NODE and rb_next/prev

The conditions got reserved. Also make rb_next() and rb_prev() check
for the empty condition.

Signed-off-by: Jens Axboe <axboe@suse.de>

3 files changed, 9 insertions, 3 deletions

diff --git a/block/as-iosched.c b/block/as-iosched.c
index 6db494333c3..9d0f15a54c6 100644
--- a/block/as-iosched.c
+++ b/block/as-iosched.c
@@ -336,7 +336,7 @@ static void as_add_arq_rb(struct as_data *ad, struct as_rq *arq)
 
 static inline void as_del_arq_rb(struct as_data *ad, struct as_rq *arq)
 {
-        if (!RB_EMPTY_NODE(&arq->rb_node)) {
+        if (RB_EMPTY_NODE(&arq->rb_node)) {
                 WARN_ON(1);
                 return;
         }
@@ -1039,7 +1039,7 @@ static void as_move_to_dispatch(struct as_data *ad, struct as_rq *arq)
         struct request *rq = arq->request;
         const int data_dir = arq->is_sync;
 
-        BUG_ON(!RB_EMPTY_NODE(&arq->rb_node));
+        BUG_ON(RB_EMPTY_NODE(&arq->rb_node));
 
         as_antic_stop(ad);
         ad->antic_status = ANTIC_OFF;
diff --git a/include/linux/rbtree.h b/include/linux/rbtree.h
index 8d5382e62c0..344bc3495dd 100644
--- a/include/linux/rbtree.h
+++ b/include/linux/rbtree.h
@@ -133,7 +133,7 @@ static inline void rb_set_color(struct rb_node *rb, int color)
 #define rb_entry(ptr, type, member) container_of(ptr, type, member)
 
 #define RB_EMPTY_ROOT(root)     ((root)->rb_node == NULL)
-#define RB_EMPTY_NODE(node)     (rb_parent(node) != node)
+#define RB_EMPTY_NODE(node)     (rb_parent(node) == node)
 #define RB_CLEAR_NODE(node)     (rb_set_parent(node, node))
 
 extern void rb_insert_color(struct rb_node *, struct rb_root *);
diff --git a/lib/rbtree.c b/lib/rbtree.c
index 1e55ba1c2ed..48499c2d88c 100644
--- a/lib/rbtree.c
+++ b/lib/rbtree.c
@@ -322,6 +322,9 @@ struct rb_node *rb_next(struct rb_node *node)
 {
         struct rb_node *parent;
 
+        if (rb_parent(node) == node)
+                return NULL;
+
         /* If we have a right-hand child, go down and then left as far
            as we can. */
         if (node->rb_right) {
@@ -348,6 +351,9 @@ struct rb_node *rb_prev(struct rb_node *node)
 {
         struct rb_node *parent;
 
+        if (rb_parent(node) == node)
+                return NULL;
+
         /* If we have a left-hand child, go down and then right as far
            as we can. */
         if (node->rb_left) {