This function may sleep, so it must not be called within an
interrupt handler. This function may be called with
- interrupts disabled, but interrupts will be turned back on if
- we need to sleep. */
+ interrupts disabled, but if it sleeps then the next scheduled
+ thread will probably turn interrupts back on. */
void
sema_down (struct semaphore *sema)
{
void
lock_acquire (struct lock *lock)
{
- enum intr_level old_level;
-
ASSERT (lock != NULL);
ASSERT (!intr_context ());
ASSERT (!lock_held_by_current_thread (lock));
- old_level = intr_disable ();
sema_down (&lock->semaphore);
lock->holder = thread_current ();
- intr_set_level (old_level);
}
/* Tries to acquires LOCK and returns true if successful or false
bool
lock_try_acquire (struct lock *lock)
{
- enum intr_level old_level;
bool success;
ASSERT (lock != NULL);
ASSERT (!lock_held_by_current_thread (lock));
- old_level = intr_disable ();
success = sema_try_down (&lock->semaphore);
if (success)
lock->holder = thread_current ();
- intr_set_level (old_level);
-
return success;
}
void
lock_release (struct lock *lock)
{
- enum intr_level old_level;
-
ASSERT (lock != NULL);
ASSERT (lock_held_by_current_thread (lock));
- old_level = intr_disable ();
lock->holder = NULL;
sema_up (&lock->semaphore);
- intr_set_level (old_level);
}
/* Returns true if the current thread holds LOCK, false