/*
* the semaphore's count is incremented by one. a blocked thread
* is awakened and re-tries to acquire the semaphore.
*/
void
sema_v(ksema_t *sp)
{
sema_impl_t *s;
kthread_t *sq, *tp;
disp_lock_t *sqlp;
s = (sema_impl_t *)sp;
sqlp = &SQHASH(s)->sq_lock;
disp_lock_enter(sqlp);
if (panicstr) {
disp_lock_exit(sqlp);
return;
}
s->s_count++;
sq = s->s_slpq;
if (sq != NULL) {
tp = sq;
ASSERT(THREAD_LOCK_HELD(tp));
sq = sq->t_link;
tp->t_link = NULL;
DTRACE_SCHED1(wakeup, kthread_t *, tp);
tp->t_sobj_ops = NULL;
tp->t_wchan = NULL;
ASSERT(tp->t_state == TS_SLEEP);
CL_WAKEUP(tp);
s->s_slpq = sq;
disp_lock_exit_high(sqlp);
thread_unlock(tp);
} else {
disp_lock_exit(sqlp);
}
}
/*
* Wake threads that are blocked in a turnstile.
*/
void
turnstile_wakeup(turnstile_t *ts, int qnum, int nthreads, kthread_t *owner)
{
turnstile_chain_t *tc = &TURNSTILE_CHAIN(ts->ts_sobj);
sleepq_t *sqp = &ts->ts_sleepq[qnum];
ASSERT(DISP_LOCK_HELD(&tc->tc_lock));
/*
* Waive any priority we may have inherited from this turnstile.
*/
if (ts->ts_inheritor != NULL) {
turnstile_pi_waive(ts);
}
while (nthreads-- > 0) {
kthread_t *t = sqp->sq_first;
ASSERT(t->t_ts == ts);
ASSERT(ts->ts_waiters > 1 || ts->ts_inheritor == NULL);
DTRACE_SCHED1(wakeup, kthread_t *, t);
turnstile_dequeue(t);
CL_WAKEUP(t); /* previous thread lock, tc_lock, not dropped */
/*
* If the caller did direct handoff of ownership,
* make the new owner inherit from this turnstile.
*/
if (t == owner) {
kthread_t *wp = ts->ts_sleepq[TS_WRITER_Q].sq_first;
kthread_t *rp = ts->ts_sleepq[TS_READER_Q].sq_first;
pri_t wpri = wp ? DISP_PRIO(wp) : 0;
pri_t rpri = rp ? DISP_PRIO(rp) : 0;
turnstile_pi_inherit(ts, t, MAX(wpri, rpri));
owner = NULL;
}
thread_unlock_high(t); /* drop run queue lock */
}
if (owner != NULL)
panic("turnstile_wakeup: owner %p not woken", (void *)owner);
disp_lock_exit(&tc->tc_lock);
}
/*
* similiar to sema_p except that it blocks at an interruptible
* priority. if a signal is present then return 1 otherwise 0.
*/
int
sema_p_sig(ksema_t *sp)
{
kthread_t *t = curthread;
klwp_t *lwp = ttolwp(t);
sema_impl_t *s;
disp_lock_t *sqlp;
if (lwp == NULL) {
sema_p(sp);
return (0);
}
s = (sema_impl_t *)sp;
sqlp = &SQHASH(s)->sq_lock;
disp_lock_enter(sqlp);
ASSERT(s->s_count >= 0);
while (s->s_count == 0) {
proc_t *p = ttoproc(t);
thread_lock_high(t);
t->t_flag |= T_WAKEABLE;
SEMA_BLOCK(s, sqlp);
lwp->lwp_asleep = 1;
lwp->lwp_sysabort = 0;
thread_unlock_nopreempt(t);
if (ISSIG(t, JUSTLOOKING) || MUSTRETURN(p, t))
setrun(t);
swtch();
t->t_flag &= ~T_WAKEABLE;
if (ISSIG(t, FORREAL) ||
lwp->lwp_sysabort || MUSTRETURN(p, t)) {
kthread_t *sq, *tp;
lwp->lwp_asleep = 0;
lwp->lwp_sysabort = 0;
disp_lock_enter(sqlp);
sq = s->s_slpq;
/*
* in case sema_v and interrupt happen
* at the same time, we need to pass the
* sema_v to the next thread.
*/
if ((sq != NULL) && (s->s_count > 0)) {
tp = sq;
ASSERT(THREAD_LOCK_HELD(tp));
sq = sq->t_link;
tp->t_link = NULL;
DTRACE_SCHED1(wakeup, kthread_t *, tp);
tp->t_sobj_ops = NULL;
tp->t_wchan = NULL;
ASSERT(tp->t_state == TS_SLEEP);
CL_WAKEUP(tp);
s->s_slpq = sq;
disp_lock_exit_high(sqlp);
thread_unlock(tp);
} else {
disp_lock_exit(sqlp);
}
return (1);
}
lwp->lwp_asleep = 0;
disp_lock_enter(sqlp);
}
s->s_count--;
disp_lock_exit(sqlp);
return (0);
}
