Sry, this is better:

static ngx_inline ngx_rbtree_node_t *
ngx_rbtree_next(ngx_rbtree_t *rbtree, ngx_rbtree_node_t *node)
{
if( node->right != rbtree->sentinel )
{
node = node->right;
while( node->left != rbtree->sentinel )
node = node->left;
}
else
{
ngx_rbtree_node_t *root;
root = rbtree->root;
while( node != root && node == node->parent->right )
node = node->parent;
if( node == root )
return rbtree->sentinel;
node = node->parent;
}
return node;
}