ia64: Validate online cpus in irq_set_affinity() callbacks

The [user space] interface does not filter out offline cpus. It merily
guarantees that the mask contains at least one online cpu.

So the selector in the irq chip implementation needs to make sure to
pick only an online cpu because otherwise:

     Offline Core 1
     Set affinity to 0xe (is valid due to online mask 0xd)
     cpumask_first will pick core 1, which is offline

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: ia64 <linux-ia64@vger.kernel.org>
Link: http://lkml.kernel.org/r/20140304203100.650414633@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/ia64/kernel/msi_ia64.c

@@ -17,12 +17,9 @@ static int ia64_set_msi_irq_affinity(struct irq_data *idata,
 {
 	struct msi_msg msg;
 	u32 addr, data;
-	int cpu = first_cpu(*cpu_mask);
+	int cpu = cpumask_first_and(cpu_mask, cpu_online_mask);
 	unsigned int irq = idata->irq;
 
-	if (!cpu_online(cpu))
-		return -1;
-
 	if (irq_prepare_move(irq, cpu))
 		return -1;
 
@@ -139,10 +136,7 @@ static int dmar_msi_set_affinity(struct irq_data *data,
 	unsigned int irq = data->irq;
 	struct irq_cfg *cfg = irq_cfg + irq;
 	struct msi_msg msg;
-	int cpu = cpumask_first(mask);
-
-	if (!cpu_online(cpu))
-		return -1;
+	int cpu = cpumask_first_and(mask, cpu_online_mask);
 
 	if (irq_prepare_move(irq, cpu))
 		return -1;