/* Up the semaphore's count and release any thread waiting at the head of the
* queue. The count is saturated to the value of the 'max' parameter specified
* in 'semaphore_init'. */
void semaphore_release(struct semaphore *s)
{
unsigned int result = THREAD_NONE;
int oldlevel = disable_irq_save();
corelock_lock(&s->cl);
struct thread_entry *thread = WQ_THREAD_FIRST(&s->queue);
if(LIKELY(thread != NULL))
{
/* a thread was queued - wake it up and keep count at 0 */
KERNEL_ASSERT(s->count == 0,
"semaphore_release->threads queued but count=%d!\n", s->count);
result = wakeup_thread(thread, WAKEUP_DEFAULT);
}
else
{
int count = s->count;
if(count < s->max)
{
/* nothing waiting - up it */
s->count = count + 1;
}
}
corelock_unlock(&s->cl);
restore_irq(oldlevel);
#if defined(HAVE_PRIORITY_SCHEDULING) && defined(is_thread_context)
/* No thread switch if not thread context */
if((result & THREAD_SWITCH) && is_thread_context())
switch_thread();
#endif
(void)result;
}
/* Release ownership of a mutex object - only owning thread must call this */
void mutex_unlock(struct mutex *m)
{
/* unlocker not being the owner is an unlocking violation */
KERNEL_ASSERT(m->blocker.thread == __running_self_entry(),
"mutex_unlock->wrong thread (%s != %s)\n",
m->blocker.thread->name,
__running_self_entry()->name);
if(m->recursion > 0)
{
/* this thread still owns lock */
m->recursion--;
return;
}
/* lock out other cores */
corelock_lock(&m->cl);
/* transfer to next queued thread if any */
struct thread_entry *thread = WQ_THREAD_FIRST(&m->queue);
if(LIKELY(thread == NULL))
{
/* no threads waiting - open the lock */
m->blocker.thread = NULL;
corelock_unlock(&m->cl);
return;
}
const int oldlevel = disable_irq_save();
/* Tranfer of owning thread is handled in the wakeup protocol
* if priorities are enabled otherwise just set it from the
* queue head. */
#ifndef HAVE_PRIORITY_SCHEDULING
m->blocker.thread = thread;
#endif
unsigned int result = wakeup_thread(thread, WAKEUP_TRANSFER);
restore_irq(oldlevel);
corelock_unlock(&m->cl);
#ifdef HAVE_PRIORITY_SCHEDULING
if(result & THREAD_SWITCH)
switch_thread();
#endif
(void)result;
}
