return
	}
	s, t0, tailtime := root.dequeue(addr)
	if s != nil {
		root.nwait.Add(-1)
	}
	unlock(&root.lock)
	if s != nil { // May be slow or even yield, so unlock first
		acquiretime := s.acquiretime
		if acquiretime != 0 {
			// Charge contention that this (delayed) unlock caused.
			// If there are N more goroutines waiting beyond the
			// one that's waking up, charge their delay as well, so that

	// For channels, waitlink is only accessed by g.
	// For semaphores, all fields (including the ones above)
	// are only accessed when holding a semaRoot lock.

	acquiretime int64
	releasetime int64
	ticket      uint32

	// isSelect indicates g is participating in a select, so
	// g.selectDone must be CAS'd to win the wake-up race.
	isSelect bool

type SemTable struct {
	semTable
}

// Enqueue simulates enqueuing a waiter for a semaphore (or lock) at addr.
func (t *SemTable) Enqueue(addr *uint32) {
	s := acquireSudog()
	s.releasetime = 0
	s.acquiretime = 0
	s.ticket = 0
	t.semTable.rootFor(addr).queue(addr, s, false)
}

// Dequeue simulates dequeuing a waiter for a semaphore (or lock) at addr.
//