What is the running time of algorithm height2(T,v) (Code Fragment 7.7) when called on a node v distinct from the root of T?

Data from in Code Fragment 7.7

A more efficient algorithm for computing the height of the subtree of tree T rooted at a node p.

int height2(const Tree& T, const Position& p) { if (p.isExternal()) return 0; int h = 0; leaf has height 0 // list of children Position List ch = p.children(); for (Iterator q = ch.begin(); q != ch.end(); ++q) h = max(h, height2(T, *q)); return 1 + h; // 1 + max height of children