Merge branch 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull CPU hotplug updates from Thomas Gleixner:
 "Yet another batch of cpu hotplug core updates and conversions:

   - Provide core infrastructure for multi instance drivers so the
     drivers do not have to keep custom lists.

   - Convert custom lists to the new infrastructure. The block-mq custom
     list conversion comes through the block tree and makes the diffstat
     tip over to more lines removed than added.

   - Handle unbalanced hotplug enable/disable calls more gracefully.

   - Remove the obsolete CPU_STARTING/DYING notifier support.

   - Convert another batch of notifier users.

   The relayfs changes which conflicted with the conversion have been
   shipped to me by Andrew.

   The remaining lot is targeted for 4.10 so that we finally can remove
   the rest of the notifiers"

* 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (46 commits)
  cpufreq: Fix up conversion to hotplug state machine
  blk/mq: Reserve hotplug states for block multiqueue
  x86/apic/uv: Convert to hotplug state machine
  s390/mm/pfault: Convert to hotplug state machine
  mips/loongson/smp: Convert to hotplug state machine
  mips/octeon/smp: Convert to hotplug state machine
  fault-injection/cpu: Convert to hotplug state machine
  padata: Convert to hotplug state machine
  cpufreq: Convert to hotplug state machine
  ACPI/processor: Convert to hotplug state machine
  virtio scsi: Convert to hotplug state machine
  oprofile/timer: Convert to hotplug state machine
  block/softirq: Convert to hotplug state machine
  lib/irq_poll: Convert to hotplug state machine
  x86/microcode: Convert to hotplug state machine
  sh/SH-X3 SMP: Convert to hotplug state machine
  ia64/mca: Convert to hotplug state machine
  ARM/OMAP/wakeupgen: Convert to hotplug state machine
  ARM/shmobile: Convert to hotplug state machine
  arm64/FP/SIMD: Convert to hotplug state machine
  ...

drivers/md/raid5.c

@@ -6349,22 +6349,20 @@ static int alloc_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu
 	return 0;
 }
 
+static int raid456_cpu_dead(unsigned int cpu, struct hlist_node *node)
+{
+	struct r5conf *conf = hlist_entry_safe(node, struct r5conf, node);
+
+	free_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
+	return 0;
+}
+
 static void raid5_free_percpu(struct r5conf *conf)
 {
-	unsigned long cpu;
-
 	if (!conf->percpu)
 		return;
 
-#ifdef CONFIG_HOTPLUG_CPU
-	unregister_cpu_notifier(&conf->cpu_notify);
-#endif
-
-	get_online_cpus();
-	for_each_possible_cpu(cpu)
-		free_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
-	put_online_cpus();
-
+	cpuhp_state_remove_instance(CPUHP_MD_RAID5_PREPARE, &conf->node);
 	free_percpu(conf->percpu);
 }
 
@@ -6383,64 +6381,28 @@ static void free_conf(struct r5conf *conf)
 	kfree(conf);
 }
 
-#ifdef CONFIG_HOTPLUG_CPU
-static int raid456_cpu_notify(struct notifier_block *nfb, unsigned long action,
-			      void *hcpu)
+static int raid456_cpu_up_prepare(unsigned int cpu, struct hlist_node *node)
 {
-	struct r5conf *conf = container_of(nfb, struct r5conf, cpu_notify);
-	long cpu = (long)hcpu;
+	struct r5conf *conf = hlist_entry_safe(node, struct r5conf, node);
 	struct raid5_percpu *percpu = per_cpu_ptr(conf->percpu, cpu);
 
-	switch (action) {
-	case CPU_UP_PREPARE:
-	case CPU_UP_PREPARE_FROZEN:
-		if (alloc_scratch_buffer(conf, percpu)) {
-			pr_err("%s: failed memory allocation for cpu%ld\n",
-			       __func__, cpu);
-			return notifier_from_errno(-ENOMEM);
-		}
-		break;
-	case CPU_DEAD:
-	case CPU_DEAD_FROZEN:
-	case CPU_UP_CANCELED:
-	case CPU_UP_CANCELED_FROZEN:
-		free_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
-		break;
-	default:
-		break;
+	if (alloc_scratch_buffer(conf, percpu)) {
+		pr_err("%s: failed memory allocation for cpu%u\n",
+		       __func__, cpu);
+		return -ENOMEM;
 	}
-	return NOTIFY_OK;
+	return 0;
 }
-#endif
 
 static int raid5_alloc_percpu(struct r5conf *conf)
 {
-	unsigned long cpu;
 	int err = 0;
 
 	conf->percpu = alloc_percpu(struct raid5_percpu);
 	if (!conf->percpu)
 		return -ENOMEM;
 
-#ifdef CONFIG_HOTPLUG_CPU
-	conf->cpu_notify.notifier_call = raid456_cpu_notify;
-	conf->cpu_notify.priority = 0;
-	err = register_cpu_notifier(&conf->cpu_notify);
-	if (err)
-		return err;
-#endif
-
-	get_online_cpus();
-	for_each_present_cpu(cpu) {
-		err = alloc_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
-		if (err) {
-			pr_err("%s: failed memory allocation for cpu%ld\n",
-			       __func__, cpu);
-			break;
-		}
-	}
-	put_online_cpus();
-
+	err = cpuhp_state_add_instance(CPUHP_MD_RAID5_PREPARE, &conf->node);
 	if (!err) {
 		conf->scribble_disks = max(conf->raid_disks,
 			conf->previous_raid_disks);
@@ -7985,10 +7947,21 @@ static struct md_personality raid4_personality =
 
 static int __init raid5_init(void)
 {
+	int ret;
+
 	raid5_wq = alloc_workqueue("raid5wq",
 		WQ_UNBOUND|WQ_MEM_RECLAIM|WQ_CPU_INTENSIVE|WQ_SYSFS, 0);
 	if (!raid5_wq)
 		return -ENOMEM;
+
+	ret = cpuhp_setup_state_multi(CPUHP_MD_RAID5_PREPARE,
+				      "md/raid5:prepare",
+				      raid456_cpu_up_prepare,
+				      raid456_cpu_dead);
+	if (ret) {
+		destroy_workqueue(raid5_wq);
+		return ret;
+	}
 	register_md_personality(&raid6_personality);
 	register_md_personality(&raid5_personality);
 	register_md_personality(&raid4_personality);
@@ -8000,6 +7973,7 @@ static void raid5_exit(void)
 	unregister_md_personality(&raid6_personality);
 	unregister_md_personality(&raid5_personality);
 	unregister_md_personality(&raid4_personality);
+	cpuhp_remove_multi_state(CPUHP_MD_RAID5_PREPARE);
 	destroy_workqueue(raid5_wq);
 }