Allow condition variables to be used in interrupt code.
Adjust the condition variable sleep loop to work correctly when code
reached by its internal CHECK_FOR_INTERRUPTS() call interacts with
another condition variable.
There are no such cases currently, but a proposed patch would do this.
Discussion:
@@ -165,8 +165,6 @@ ConditionVariableTimedSleep(ConditionVariable *cv, long timeout,
/* Reset latch before examining the state of the wait list. */
ResetLatch(MyLatch);
- CHECK_FOR_INTERRUPTS();
-
/*
* If this process has been taken out of the wait list, then we know
* that it has been signaled by ConditionVariableSignal (or
@@ -190,6 +188,15 @@ ConditionVariableTimedSleep(ConditionVariable *cv, long timeout,
}
SpinLockRelease(&cv->mutex);
+ /*
+ * Check for interrupts, and return spuriously if that caused the
+ * current sleep target to change (meaning that interrupt handler code
+ * waited for a different condition variable).
+ */
+ CHECK_FOR_INTERRUPTS();
+ if (cv != cv_sleep_target)
+ done = true;
+
/* We were signaled, so return */
if (done)
return false;
