md/raid5: Cleanup cpu hotplug notifier

The raid456_cpu_notify() hotplug callback lacks handling of the
CPU_UP_CANCELED case. That means if CPU_UP_PREPARE fails, the scratch
buffer is leaked.

Add handling for CPU_UP_CANCELED[_FROZEN] hotplug notifier transitions
to free the scratch buffer.

CC: Shaohua Li <shli@kernel.org>
CC: linux-raid@vger.kernel.org
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Signed-off-by: Shaohua Li <shli@fb.com>

drivers/md/raid5.c

@@ -6381,6 +6381,8 @@ static int raid456_cpu_notify(struct notifier_block *nfb, unsigned long action,
 		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: