That's probably an obvious question but anyway. In the following code executed 
for example in read(2) driver callback:

---cut---
sc->sc_ospl = spltty();
if (!tsleep(&sc->sc_sem, PZERO | PCATCH, "foo", 0)) {
	(1)
	....
}
splx(sc->sc_ospl);
---cut---

At point (1) do i need to call spltty() once again or tsleep(9) restores 
previous system priority level?

// wbr