kernel: Panic on attempting to release a semaphore with interrupts disabled...

... and B_DO_NOT_RESCHEDULE unset. We already have equivalent panics
for mutexes and condition variables, so it seems to make sense to
check for this too.

There have been some bug reports recently about hard deadlocks with
symptoms (i.e. kernel debugger can't even be summoned) that match
"interrupt handler thread was context-switched while holding interrupt
lock," and this is the only major remaining path to that without
such a check.

This would have also helped me with recent FreeBSD driver porting;
I forgot to pass the flag once and deadlocked my system in precisely
this manner.

src/system/kernel/sem.cpp

@@ -925,6 +925,12 @@ release_sem_etc(sem_id id, int32 count, uint32 flags)
 		return B_BAD_SEM_ID;
 	if (count <= 0 && (flags & B_RELEASE_ALL) == 0)
 		return B_BAD_VALUE;
+#if KDEBUG
+	if ((flags & B_DO_NOT_RESCHEDULE) == 0 && !are_interrupts_enabled()) {
+		panic("release_sem_etc(): called with interrupts disabled and "
+			"rescheduling allowed for sem_id %ld", id);
+	}
+#endif
 
 	InterruptsLocker _;
 	SpinLocker semLocker(sSems[slot].lock);