x86: Eliminate pointless adjustment attempts in fixup_irqs()

Not only when an IRQ's affinity equals cpu_online_mask is there
no need to actually try to adjust the affinity, but also when
it's a subset thereof. This particularly avoids adjustment
attempts during system shutdown to any IRQs bound to CPU#0.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Gary Hade <garyhade@us.ibm.com>
LKML-Reference: <4D5D52C2020000780003272C@vpn.id2.novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/irq.c

@@ -310,7 +310,7 @@ void fixup_irqs(void)
 		data = &desc->irq_data;
 		affinity = data->affinity;
 		if (!irq_has_action(irq) ||
-		    cpumask_equal(affinity, cpu_online_mask)) {
+		    cpumask_subset(affinity, cpu_online_mask)) {
 			raw_spin_unlock(&desc->lock);
 			continue;
 		}