[PATCH] ia64: BUG if smp_call_function is called with interrupts disabled

smp_call_function() may not be called with interrupts disabled.
Violating this precondition leads to bugs that are hard to reproduce
and even harder to diagnose.  Thus, catch violations with BUG_ON().

arch/ia64/kernel/smp.c

@@ -308,6 +308,8 @@ smp_call_function (void (*func) (void *info), void *info, int nonatomic, int wai
 	if (!cpus)
 		return 0;
 
+	BUG_ON(irqs_disabled());
+
 	data.func = func;
 	data.info = info;
 	atomic_set(&data.started, 0);