C_WAITACT
xfer->c_flags |= C_WAITACT;
xfer->c_flags &= ~C_WAITACT;
if (__predict_false(xfer->c_flags & C_WAITACT)) {
if (__predict_false(xfer->c_flags & (C_WAITACT|C_WAITTIMO))) {
KASSERT((xfer->c_flags & (C_WAITACT|C_FREE)) == 0);