lockdep: Fix lockdep_no_validate against IRQ states

Thomas noticed that a lock marked with lockdep_set_novalidate_class()
will still trigger warnings for IRQ inversions. Cure this by skipping
those when marking irq state.
Reported-and-tested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-2dp5vmpsxeraqm42kgww6ge2@git.kernel.orgSigned-off-by: Ingo Molnar <mingo@elte.hu>

kernel/lockdep.c

@@ -2468,6 +2468,9 @@ mark_held_locks(struct task_struct *curr, enum mark_type mark)
 
 		BUG_ON(usage_bit >= LOCK_USAGE_STATES);
 
+		if (hlock_class(hlock)->key == &__lockdep_no_validate__)
+			continue;
+
 		if (!mark_lock(curr, hlock, usage_bit))
 			return 0;
 	}