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subr_turnstile: Extract some common code to a helper.

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Code walks the list of contested turnstiles to calculate the priority
to unlend.

Reviewed by:	markj
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
This commit is contained in:
Konstantin Belousov 2019-05-16 13:17:57 +00:00
parent 3cac4083ef
commit a9fd669b4a
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=347694
1 changed files with 22 additions and 15 deletions
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37
sys/kern/subr_turnstile.c
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@ -897,6 +897,24 @@ turnstile_broadcast(struct turnstile *ts, int queue)
}
}
static u_char
turnstile_calc_unlend_prio_locked(struct thread *td)
{
struct turnstile *nts;
u_char cp, pri;
THREAD_LOCK_ASSERT(td, MA_OWNED);
mtx_assert(&td_contested_lock, MA_OWNED);
pri = PRI_MAX;
LIST_FOREACH(nts, &td->td_contested, ts_link) {
cp = turnstile_first_waiter(nts)->td_priority;
if (cp < pri)
pri = cp;
}
return (pri);
}
/*
* Wakeup all threads on the pending list and adjust the priority of the
* current thread appropriately. This must be called with the turnstile
@ -906,9 +924,8 @@ void
turnstile_unpend(struct turnstile *ts)
{
TAILQ_HEAD( ,thread) pending_threads;
struct turnstile *nts;
struct thread *td;
u_char cp, pri;
u_char pri;
MPASS(ts != NULL);
mtx_assert(&ts->ts_lock, MA_OWNED);
@ -932,7 +949,6 @@ turnstile_unpend(struct turnstile *ts)
* priority however.
*/
td = curthread;
pri = PRI_MAX;
thread_lock(td);
mtx_lock_spin(&td_contested_lock);
/*
@ -946,11 +962,7 @@ turnstile_unpend(struct turnstile *ts)
ts->ts_owner = NULL;
LIST_REMOVE(ts, ts_link);
}
LIST_FOREACH(nts, &td->td_contested, ts_link) {
cp = turnstile_first_waiter(nts)->td_priority;
if (cp < pri)
pri = cp;
}
pri = turnstile_calc_unlend_prio_locked(td);
mtx_unlock_spin(&td_contested_lock);
sched_unlend_prio(td, pri);
thread_unlock(td);
@ -991,7 +1003,7 @@ void
turnstile_disown(struct turnstile *ts)
{
struct thread *td;
u_char cp, pri;
u_char pri;
MPASS(ts != NULL);
mtx_assert(&ts->ts_lock, MA_OWNED);
@ -1017,15 +1029,10 @@ turnstile_disown(struct turnstile *ts)
* priority however.
*/
td = curthread;
pri = PRI_MAX;
thread_lock(td);
mtx_unlock_spin(&ts->ts_lock);
mtx_lock_spin(&td_contested_lock);
LIST_FOREACH(ts, &td->td_contested, ts_link) {
cp = turnstile_first_waiter(ts)->td_priority;
if (cp < pri)
pri = cp;
}
pri = turnstile_calc_unlend_prio_locked(td);
mtx_unlock_spin(&td_contested_lock);
sched_unlend_prio(td, pri);
thread_unlock(td);