Function turnstile_broadcast

freebsd/kern/subr_turnstile.c:879–922

* Put all blocked threads on the pending list. This must be called with * the turnstile chain locked. */

 * the turnstile chain locked.
 */
void
turnstile_broadcast(struct turnstile *ts, int queue)
{
	struct turnstile_chain *tc __unused;
	struct turnstile *ts1;
	struct thread *td;

	MPASS(ts != NULL);
	mtx_assert(&ts->ts_lock, MA_OWNED);
	MPASS(curthread->td_proc->p_magic == P_MAGIC);
	MPASS(ts->ts_owner == curthread || ts->ts_owner == NULL);
	/*
	 * We must have the chain locked so that we can remove the empty
	 * turnstile from the hash queue.
	 */
	tc = TC_LOOKUP(ts->ts_lockobj);
	mtx_assert(&tc->tc_lock, MA_OWNED);
	MPASS(queue == TS_SHARED_QUEUE || queue == TS_EXCLUSIVE_QUEUE);

	/*
	 * Transfer the blocked list to the pending list.
	 */
	mtx_lock_spin(&td_contested_lock);
	TAILQ_CONCAT(&ts->ts_pending, &ts->ts_blocked[queue], td_lockq);
	mtx_unlock_spin(&td_contested_lock);

	/*
	 * Give a turnstile to each thread.  The last thread gets
	 * this turnstile if the turnstile is empty.
	 */
	TAILQ_FOREACH(td, &ts->ts_pending, td_lockq) {
		if (LIST_EMPTY(&ts->ts_free)) {
			MPASS(TAILQ_NEXT(td, td_lockq) == NULL);
			ts1 = ts;
#ifdef TURNSTILE_PROFILING
			tc->tc_depth--;
#endif
		} else
			ts1 = LIST_FIRST(&ts->ts_free);
		MPASS(ts1 != NULL);
		LIST_REMOVE(ts1, ts_hash);
		td->td_turnstile = ts1;
	}
}

static u_char
turnstile_calc_unlend_prio_locked(struct thread *td)