Fix nil handling

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

diff --git a/urcu-rbtree.c b/urcu-rbtree.c
index abe6de5cd1b3a0c9a2b72b768f06e72848ea18bc..7292b97f266b87906cedf42d7dd5953152e42eeb 100644 (file)
--- a/urcu-rbtree.c
+++ b/urcu-rbtree.c
@@ -57,7 +57,7 @@ struct rcu_rbtree_node* rcu_rbtree_search(struct rcu_rbtree_node *x,
 {
        x = rcu_dereference(x);
 
-       while (x != NULL && k != x->key) {
+       while (x != &rcu_rbtree_nil && k != x->key) {
                if (k < x->key)
                        x = rcu_dereference(x->left);
                else
@@ -73,7 +73,7 @@ struct rcu_rbtree_node *rcu_rbtree_min(struct rcu_rbtree_node *x,
 
        x = rcu_dereference(x);
 
-       while ((xl = rcu_dereference(x->left)) != NULL)
+       while ((xl = rcu_dereference(x->left)) != &rcu_rbtree_nil)
                x = xl;
        return x;
 }
@@ -85,7 +85,7 @@ struct rcu_rbtree_node *rcu_rbtree_max(struct rcu_rbtree_node *x,
 
        x = rcu_dereference(x);
 
-       while ((xr = rcu_dereference(x->right)) != NULL)
+       while ((xr = rcu_dereference(x->right)) != &rcu_rbtree_nil)
                x = xr;
        return x;
 }
@@ -101,10 +101,10 @@ struct rcu_rbtree_node *rcu_rbtree_next(struct rcu_rbtree_node *x,
 
        x = rcu_dereference(x);
 
-       if ((xr = rcu_dereference(x->right)) != NULL)
+       if ((xr = rcu_dereference(x->right)) != &rcu_rbtree_nil)
                return rcu_rbtree_min(xr, comp);
        y = rcu_dereference(x->p);
-       while (y != NULL && x == rcu_dereference(y->right)) {
+       while (y != &rcu_rbtree_nil && x == rcu_dereference(y->right)) {
                x = y;
                y = rcu_dereference(y->p);
        }
@@ -118,10 +118,10 @@ struct rcu_rbtree_node *rcu_rbtree_prev(struct rcu_rbtree_node *x,
 
        x = rcu_dereference(x);
 
-       if ((xl = rcu_dereference(x->left)) != NULL)
+       if ((xl = rcu_dereference(x->left)) != &rcu_rbtree_nil)
                return rcu_rbtree_max(xl, comp);
        y = rcu_dereference(x->p);
-       while (y != NULL && x == rcu_dereference(y->left)) {
+       while (y != &rcu_rbtree_nil && x == rcu_dereference(y->left)) {
                x = y;
                y = rcu_dereference(y->p);
        }
@@ -160,16 +160,21 @@ static struct rcu_rbtree_node *left_rotate(struct rcu_rbtree_node **root,
        if (x != &rcu_rbtree_nil) {
                xc = rballoc();
                *xc = *x;
-               /* Modify children and parents in the node copies */
+       }
+
+       if (y != &rcu_rbtree_nil) {
+               yc = rballoc();
+               *yc = *y;
+       }
+
+       /* Modify children and parents in the node copies */
+       if (x != &rcu_rbtree_nil) {
                xc->right = y->left;
                xc->p = yc;
        } else
                xc = &rcu_rbtree_nil;
 
        if (y != &rcu_rbtree_nil) {
-               yc = rballoc();
-               *yc = *y;
-               /* Modify children and parents in the node copies */
                yc->left = xc;
                yc->p = x->p;
        } else
@@ -241,16 +246,21 @@ static struct rcu_rbtree_node *right_rotate(struct rcu_rbtree_node **root,
        if (x != &rcu_rbtree_nil) {
                xc = rballoc();
                *xc = *x;
-               /* Modify children and parents in the node copies */
+       }
+
+       if (y != &rcu_rbtree_nil) {
+               yc = rballoc();
+               *yc = *y;
+       }
+
+       /* Modify children and parents in the node copies */
+       if (x != &rcu_rbtree_nil) {
                xc->left = y->right;
                xc->p = yc;
        } else
                xc = &rcu_rbtree_nil;
 
        if (y != &rcu_rbtree_nil) {
-               yc = rballoc();
-               *yc = *y;
-               /* Modify children and parents in the node copies */
                yc->right = xc;
                yc->p = x->p;
        } else
@@ -330,8 +340,7 @@ static void rcu_rbtree_insert_fixup(struct rcu_rbtree_node **root,
                                }
                                z->p->color = COLOR_BLACK;
                                z->p->p->color = COLOR_RED;
-                               z = right_rotate(root, z->p->p,
-                                                rballoc, rbfree);
+                               right_rotate(root, z->p->p, rballoc, rbfree);
                        }
                } else {
                        y = z->p->p->left;
@@ -348,8 +357,7 @@ static void rcu_rbtree_insert_fixup(struct rcu_rbtree_node **root,
                                }
                                z->p->color = COLOR_BLACK;
                                z->p->p->color = COLOR_RED;
-                               z = left_rotate(root, z->p->p,
-                                               rballoc, rbfree);
+                               left_rotate(root, z->p->p, rballoc, rbfree);
                        }
                }
        }
@@ -536,9 +544,13 @@ rcu_rbtree_remove_nonil(struct rcu_rbtree_node **root,
 
        x = y->right;
 
-       xc = rballoc();
+       if (x != &rcu_rbtree_nil) {
+               xc = rballoc();
+               *xc = *x;
+       } else
+               xc = &rcu_rbtree_nil;
+
        yc = rballoc();
-       *xc = *x;
        *yc = *y;
 
        /* Update parent and children pointers within copies */
@@ -584,14 +596,16 @@ rcu_rbtree_remove_nonil(struct rcu_rbtree_node **root,
        else
                _STORE_SHARED(z->p->right, yc);
 
-       /* Reparent xc's children to xc. */
-       _STORE_SHARED(xc->right->p, xc);
-       _STORE_SHARED(xc->left->p, xc);
+       if (x != &rcu_rbtree_nil) {
+               /* Reparent xc's children to xc. */
+               _STORE_SHARED(xc->right->p, xc);
+               _STORE_SHARED(xc->left->p, xc);
+               defer_rcu(rbfree, x);
+       }
+
        /* Reparent yc's children to yc */
        _STORE_SHARED(yc->right->p, yc);
        _STORE_SHARED(yc->left->p, yc);
-
-       defer_rcu(rbfree, x);
        defer_rcu(rbfree, y);
 
        return xc;