Fix rbtree nil beta rotation

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/urcu-rbtree.c b/urcu-rbtree.c
index e16c6ded2d6eb05e749ed538a7be759fd46f0749..d0e6c882d6a22e37794a515cf52f114b3feb5a1f 100644 (file)
--- a/urcu-rbtree.c
+++ b/urcu-rbtree.c
@@ -37,6 +37,12 @@
 #include <urcu-rbtree.h>
 #include <urcu-pointer.h>
 
+#ifdef DEBUG
+#define dbg_printf(args...)    printf(args)
+#else
+#define dbg_printf(args...)
+#endif
+
 /*
  * TODO
  * Deal with memory allocation errors.
@@ -165,6 +171,8 @@ static struct rcu_rbtree_node *left_rotate(struct rcu_rbtree_node **root,
 {
        struct rcu_rbtree_node *xc, *y, *yc, *b, *bc;
 
+       dbg_printf("left rotate %p\n", x->key);
+
        y = x->right;
 
        if (x != &rcu_rbtree_nil) {
@@ -188,7 +196,8 @@ static struct rcu_rbtree_node *left_rotate(struct rcu_rbtree_node **root,
                *bc = *b;
                assert(b->pos == IS_LEFT);
                bc->pos = IS_RIGHT;
-       }
+       } else
+               bc = &rcu_rbtree_nil;
 
        /* Modify children and parents in the node copies */
        if (x != &rcu_rbtree_nil) {
@@ -269,6 +278,8 @@ static struct rcu_rbtree_node *right_rotate(struct rcu_rbtree_node **root,
 {
        struct rcu_rbtree_node *x, *xc, *yc, *b, *bc;;
 
+       dbg_printf("right rotate %p\n", y->key);
+
        x = y->left;
 
        if (x != &rcu_rbtree_nil) {
@@ -292,7 +303,8 @@ static struct rcu_rbtree_node *right_rotate(struct rcu_rbtree_node **root,
                *bc = *b;
                assert(b->pos == IS_RIGHT);
                bc->pos = IS_LEFT;
-       }
+       } else
+               bc = &rcu_rbtree_nil;
 
        /* Modify children and parents in the node copies */
        if (x != &rcu_rbtree_nil) {
@@ -339,29 +351,6 @@ static struct rcu_rbtree_node *right_rotate(struct rcu_rbtree_node **root,
        return yc;
 }
 
-#if 0 //orig
-static void right_rotate(struct rcu_rbtree_node **root,
-                        struct rcu_rbtree_node *x,
-                        rcu_rbtree_alloc rballoc)
-{
-       struct rcu_rbtree_node *y;
-
-       y = x->left;
-       x->left = y->right;
-       if (y->right != &rcu_rbtree_nil)
-               y->right->p = x;
-       y->p = x->p;
-       if (x->p == &rcu_rbtree_nil)
-               *root = y;
-       else if (x == x->p->right)
-               x->p->right = y;
-       else
-               x->p->left = y;
-       y->right = x;
-       x->p = y;
-}
-#endif //0
-
 static void rcu_rbtree_insert_fixup(struct rcu_rbtree_node **root,
                                    struct rcu_rbtree_node *z,
                                    rcu_rbtree_alloc rballoc,
@@ -369,6 +358,8 @@ static void rcu_rbtree_insert_fixup(struct rcu_rbtree_node **root,
 {
        struct rcu_rbtree_node *y;
 
+       dbg_printf("insert fixup %p\n", z->key);
+
        while (z->p->color == COLOR_RED) {
                if (z->p == z->p->p->left) {
                        y = z->p->p->right;
@@ -422,6 +413,8 @@ int rcu_rbtree_insert(struct rcu_rbtree_node **root,
 {
        struct rcu_rbtree_node *x, *y;
 
+       dbg_printf("insert %p\n", z->key);
+
        y = &rcu_rbtree_nil;
        x = *root;
 
@@ -479,6 +472,8 @@ rcu_rbtree_transplant(struct rcu_rbtree_node **root,
 {
        struct rcu_rbtree_node *vc;
 
+       dbg_printf("transplant %p\n", v->key);
+
        if (v != &rcu_rbtree_nil) {
                vc = rballoc();
                *vc = *v;
@@ -524,6 +519,8 @@ static void rcu_rbtree_remove_fixup(struct rcu_rbtree_node **root,
                                    rcu_rbtree_alloc rballoc,
                                    rcu_rbtree_free rbfree)
 {
+       dbg_printf("remove fixup %p\n", x->key);
+
        while (x != *root && x->color == COLOR_BLACK) {
                if (x == x->p->left) {
                        struct rcu_rbtree_node *w, *t;
@@ -601,6 +598,8 @@ rcu_rbtree_remove_nonil(struct rcu_rbtree_node **root,
 {
        struct rcu_rbtree_node *x, *xc, *yc;
 
+       dbg_printf("remove nonil %p\n", z->key);
+
        x = y->right;
 
        if (x != &rcu_rbtree_nil) {
@@ -685,6 +684,8 @@ int rcu_rbtree_remove(struct rcu_rbtree_node **root,
        struct rcu_rbtree_node *x, *y;
        unsigned int y_original_color;
 
+       dbg_printf("remove %p\n", z->key);
+
        y = z;
        y_original_color = y->color;