Author: mjg
Date: Tue Aug 4 23:00:00 2020
New Revision: 363871
URL: https://svnweb.freebsd.org/changeset/base/363871
Log:
mtx: add mtx_wait_unlocked
Modified:
head/sys/kern/kern_mutex.c
head/sys/sys/mutex.h
Modified: head/sys/kern/kern_mutex.c
==============================================================================
--- head/sys/kern/kern_mutex.c Tue Aug 4 21:58:43 2020 (r363870)
+++ head/sys/kern/kern_mutex.c Tue Aug 4 23:00:00 2020 (r363871)
@@ -1275,6 +1275,35 @@ mtx_spin_wait_unlocked(struct mtx *m)
}
}
+void
+mtx_wait_unlocked(struct mtx *m)
+{
+ struct thread *owner;
+ uintptr_t v;
+
+ KASSERT(m->mtx_lock != MTX_DESTROYED,
+ ("%s() of destroyed mutex %p", __func__, m));
+ KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
+ ("%s() not a sleep mutex %p (%s)", __func__, m,
+ m->lock_object.lo_name));
+ KASSERT(!mtx_owned(m), ("%s() waiting on myself on lock %p (%s)",
__func__, m,
+ m->lock_object.lo_name));
+
+ for (;;) {
+ v = atomic_load_acq_ptr(&m->mtx_lock);
+ if (v == MTX_UNOWNED) {
+ break;
+ }
+ owner = lv_mtx_owner(v);
+ if (!TD_IS_RUNNING(owner)) {
+ mtx_lock(m);
+ mtx_unlock(m);
+ break;
+ }
+ cpu_spinwait();
+ }
+}
+
#ifdef DDB
void
db_show_mtx(const struct lock_object *lock)
Modified: head/sys/sys/mutex.h
==============================================================================
--- head/sys/sys/mutex.h Tue Aug 4 21:58:43 2020 (r363870)
+++ head/sys/sys/mutex.h Tue Aug 4 23:00:00 2020 (r363871)
@@ -106,6 +106,7 @@ void __mtx_unlock_sleep(volatile uintptr_t *c,
uintptr
void __mtx_lock_sleep(volatile uintptr_t *c, uintptr_t v);
void __mtx_unlock_sleep(volatile uintptr_t *c, uintptr_t v);
#endif
+void mtx_wait_unlocked(struct mtx *m);
#ifdef SMP
#if LOCK_DEBUG > 0
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