genirq/cpuhotplug: Remove irq disabling logic

This is called from stop_machine() with interrupts disabled. No point in
disabling them some more.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>
Link: http://lkml.kernel.org/r/20170619235445.198042748@linutronix.de

kernel/irq/cpuhotplug.c

@@ -59,11 +59,8 @@ static bool migrate_one_irq(struct irq_desc *desc)
  */
 void irq_migrate_all_off_this_cpu(void)
 {
-	unsigned int irq;
 	struct irq_desc *desc;
-	unsigned long flags;
-
-	local_irq_save(flags);
+	unsigned int irq;
 
 	for_each_active_irq(irq) {
 		bool affinity_broken;
@@ -73,10 +70,9 @@ void irq_migrate_all_off_this_cpu(void)
 		affinity_broken = migrate_one_irq(desc);
 		raw_spin_unlock(&desc->lock);
 
-		if (affinity_broken)
-			pr_warn_ratelimited("IRQ%u no longer affine to CPU%u\n",
+		if (affinity_broken) {
+			pr_warn_ratelimited("IRQ %u: no longer affine to CPU%u\n",
 					    irq, smp_processor_id());
+		}
 	}
-
-	local_irq_restore(flags);
 }