lib/irq_poll: Convert to hotplug state machine

Install the callbacks via the state machine.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160906170457.32393-8-bigeasy@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

include/linux/cpuhotplug.h

@@ -22,6 +22,7 @@ enum cpuhp_state {
 	CPUHP_CPUIDLE_DEAD,
 	CPUHP_ARM64_FPSIMD_DEAD,
 	CPUHP_ARM_OMAP_WAKE_DEAD,
+	CPUHP_IRQ_POLL_DEAD,
 	CPUHP_WORKQUEUE_PREP,
 	CPUHP_POWER_NUMA_PREPARE,
 	CPUHP_HRTIMERS_PREPARE,

lib/irq_poll.c

@@ -184,30 +184,21 @@ void irq_poll_init(struct irq_poll *iop, int weight, irq_poll_fn *poll_fn)
 }
 EXPORT_SYMBOL(irq_poll_init);
 
-static int irq_poll_cpu_notify(struct notifier_block *self,
-				 unsigned long action, void *hcpu)
+static int irq_poll_cpu_dead(unsigned int cpu)
 {
 	/*
 	 * If a CPU goes away, splice its entries to the current CPU
 	 * and trigger a run of the softirq
 	 */
-	if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
-		int cpu = (unsigned long) hcpu;
-
 	local_irq_disable();
 	list_splice_init(&per_cpu(blk_cpu_iopoll, cpu),
 			 this_cpu_ptr(&blk_cpu_iopoll));
 	__raise_softirq_irqoff(IRQ_POLL_SOFTIRQ);
 	local_irq_enable();
-	}
 
-	return NOTIFY_OK;
+	return 0;
 }
 
-static struct notifier_block irq_poll_cpu_notifier = {
-	.notifier_call	= irq_poll_cpu_notify,
-};
-
 static __init int irq_poll_setup(void)
 {
 	int i;
@@ -216,7 +207,8 @@ static __init int irq_poll_setup(void)
 		INIT_LIST_HEAD(&per_cpu(blk_cpu_iopoll, i));
 
 	open_softirq(IRQ_POLL_SOFTIRQ, irq_poll_softirq);
-	register_hotcpu_notifier(&irq_poll_cpu_notifier);
+	cpuhp_setup_state_nocalls(CPUHP_IRQ_POLL_DEAD, "irq_poll:dead", NULL,
+				  irq_poll_cpu_dead);
 	return 0;
 }
 subsys_initcall(irq_poll_setup);