snode_cb
if (mdb_walk("snode", (mdb_walk_cb_t)snode_cb, &sd) == -1) {
snode_cb(addr, &snode, &sd);
if (mdb_pwalk("snode", (mdb_walk_cb_t)snode_cb, &sd, 0) != 0)
if (mdb_pwalk("snode", (mdb_walk_cb_t)snode_cb, &sd, 0) != 0)