VT9P_MTX
if (msleep(req, VT9P_MTX(chan), 0, "chan lock", vt9p_ackmaxidle * hz)) {
cv_wait(&chan->submit_cv, VT9P_MTX(chan));
#define VT9P_LOCK(_sc) mtx_lock(VT9P_MTX(_sc))
#define VT9P_UNLOCK(_sc) mtx_unlock(VT9P_MTX(_sc))
#define VT9P_LOCK_INIT(_sc) mtx_init(VT9P_MTX(_sc), \
#define VT9P_LOCK_DESTROY(_sc) mtx_destroy(VT9P_MTX(_sc))