net/iucv: Convert to hotplug state machine

Install the callbacks via the state machine and let the core invoke the
callbacks on the already online CPUs. The smp function calls in the
online/downprep callbacks are not required as the callback is guaranteed to
be invoked on the upcoming/outgoing cpu.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: linux-s390@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: Ursula Braun <ubraun@linux.vnet.ibm.com>
Cc: rt@linuxtronix.de
Link: http://lkml.kernel.org/r/20161117183541.8588-13-bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

include/linux/cpuhotplug.h

@@ -60,6 +60,7 @@ enum cpuhp_state {
 	CPUHP_BLK_MQ_PREPARE,
 	CPUHP_NET_FLOW_PREPARE,
 	CPUHP_TOPOLOGY_PREPARE,
+	CPUHP_NET_IUCV_PREPARE,
 	CPUHP_TIMERS_DEAD,
 	CPUHP_NOTF_ERR_INJ_PREPARE,
 	CPUHP_MIPS_SOC_PREPARE,

net/iucv/iucv.c

@@ -639,7 +639,7 @@ static void iucv_disable(void)
 	put_online_cpus();
 }
 
-static void free_iucv_data(int cpu)
+static int iucv_cpu_dead(unsigned int cpu)
 {
 	kfree(iucv_param_irq[cpu]);
 	iucv_param_irq[cpu] = NULL;
@@ -647,9 +647,10 @@ static void free_iucv_data(int cpu)
 	iucv_param[cpu] = NULL;
 	kfree(iucv_irq_data[cpu]);
 	iucv_irq_data[cpu] = NULL;
+	return 0;
 }
 
-static int alloc_iucv_data(int cpu)
+static int iucv_cpu_prepare(unsigned int cpu)
 {
 	/* Note: GFP_DMA used to get memory below 2G */
 	iucv_irq_data[cpu] = kmalloc_node(sizeof(struct iucv_irq_data),
@@ -671,58 +672,38 @@ static int alloc_iucv_data(int cpu)
 	return 0;
 
 out_free:
-	free_iucv_data(cpu);
+	iucv_cpu_dead(cpu);
 	return -ENOMEM;
 }
 
-static int iucv_cpu_notify(struct notifier_block *self,
-				     unsigned long action, void *hcpu)
+static int iucv_cpu_online(unsigned int cpu)
 {
-	cpumask_t cpumask;
-	long cpu = (long) hcpu;
-
-	switch (action) {
-	case CPU_UP_PREPARE:
-	case CPU_UP_PREPARE_FROZEN:
-		if (alloc_iucv_data(cpu))
-			return notifier_from_errno(-ENOMEM);
-		break;
-	case CPU_UP_CANCELED:
-	case CPU_UP_CANCELED_FROZEN:
-	case CPU_DEAD:
-	case CPU_DEAD_FROZEN:
-		free_iucv_data(cpu);
-		break;
-	case CPU_ONLINE:
-	case CPU_ONLINE_FROZEN:
-	case CPU_DOWN_FAILED:
-	case CPU_DOWN_FAILED_FROZEN:
-		if (!iucv_path_table)
-			break;
-		smp_call_function_single(cpu, iucv_declare_cpu, NULL, 1);
-		break;
-	case CPU_DOWN_PREPARE:
-	case CPU_DOWN_PREPARE_FROZEN:
-		if (!iucv_path_table)
-			break;
-		cpumask_copy(&cpumask, &iucv_buffer_cpumask);
-		cpumask_clear_cpu(cpu, &cpumask);
-		if (cpumask_empty(&cpumask))
-			/* Can't offline last IUCV enabled cpu. */
-			return notifier_from_errno(-EINVAL);
-		smp_call_function_single(cpu, iucv_retrieve_cpu, NULL, 1);
-		if (cpumask_empty(&iucv_irq_cpumask))
-			smp_call_function_single(
-				cpumask_first(&iucv_buffer_cpumask),
-				iucv_allow_cpu, NULL, 1);
-		break;
-	}
-	return NOTIFY_OK;
+	if (!iucv_path_table)
+		return 0;
+	iucv_declare_cpu(NULL);
+	return 0;
 }
 
-static struct notifier_block __refdata iucv_cpu_notifier = {
-	.notifier_call = iucv_cpu_notify,
-};
+static int iucv_cpu_down_prep(unsigned int cpu)
+{
+	cpumask_t cpumask;
+
+	if (!iucv_path_table)
+		return 0;
+
+	cpumask_copy(&cpumask, &iucv_buffer_cpumask);
+	cpumask_clear_cpu(cpu, &cpumask);
+	if (cpumask_empty(&cpumask))
+		/* Can't offline last IUCV enabled cpu. */
+		return -EINVAL;
+
+	iucv_retrieve_cpu(NULL);
+	if (!cpumask_empty(&iucv_irq_cpumask))
+		return 0;
+	smp_call_function_single(cpumask_first(&iucv_buffer_cpumask),
+				 iucv_allow_cpu, NULL, 1);
+	return 0;
+}
 
 /**
  * iucv_sever_pathid
@@ -2027,6 +2008,7 @@ struct iucv_interface iucv_if = {
 };
 EXPORT_SYMBOL(iucv_if);
 
+static enum cpuhp_state iucv_online;
 /**
  * iucv_init
  *
@@ -2035,7 +2017,6 @@ EXPORT_SYMBOL(iucv_if);
 static int __init iucv_init(void)
 {
 	int rc;
-	int cpu;
 
 	if (!MACHINE_IS_VM) {
 		rc = -EPROTONOSUPPORT;
@@ -2054,23 +2035,19 @@ static int __init iucv_init(void)
 		goto out_int;
 	}
 
-	cpu_notifier_register_begin();
-
-	for_each_online_cpu(cpu) {
-		if (alloc_iucv_data(cpu)) {
-			rc = -ENOMEM;
-			goto out_free;
-		}
-	}
-	rc = __register_hotcpu_notifier(&iucv_cpu_notifier);
+	rc = cpuhp_setup_state(CPUHP_NET_IUCV_PREPARE, "net/iucv:prepare",
+			       iucv_cpu_prepare, iucv_cpu_dead);
 	if (rc)
 		goto out_free;
-
-	cpu_notifier_register_done();
+	rc = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "net/iucv:online",
+			       iucv_cpu_online, iucv_cpu_down_prep);
+	if (rc < 0)
+		goto out_free;
+	iucv_online = rc;
 
 	rc = register_reboot_notifier(&iucv_reboot_notifier);
 	if (rc)
-		goto out_cpu;
+		goto out_free;
 	ASCEBC(iucv_error_no_listener, 16);
 	ASCEBC(iucv_error_no_memory, 16);
 	ASCEBC(iucv_error_pathid, 16);
@@ -2084,14 +2061,10 @@ static int __init iucv_init(void)
 
 out_reboot:
 	unregister_reboot_notifier(&iucv_reboot_notifier);
-out_cpu:
-	cpu_notifier_register_begin();
-	__unregister_hotcpu_notifier(&iucv_cpu_notifier);
 out_free:
-	for_each_possible_cpu(cpu)
-		free_iucv_data(cpu);
-
-	cpu_notifier_register_done();
+	if (iucv_online)
+		cpuhp_remove_state(iucv_online);
+	cpuhp_remove_state(CPUHP_NET_IUCV_PREPARE);
 
 	root_device_unregister(iucv_root);
 out_int:
@@ -2110,7 +2083,6 @@ out:
 static void __exit iucv_exit(void)
 {
 	struct iucv_irq_list *p, *n;
-	int cpu;
 
 	spin_lock_irq(&iucv_queue_lock);
 	list_for_each_entry_safe(p, n, &iucv_task_queue, list)
@@ -2119,11 +2091,9 @@ static void __exit iucv_exit(void)
 		kfree(p);
 	spin_unlock_irq(&iucv_queue_lock);
 	unregister_reboot_notifier(&iucv_reboot_notifier);
-	cpu_notifier_register_begin();
-	__unregister_hotcpu_notifier(&iucv_cpu_notifier);
-	for_each_possible_cpu(cpu)
-		free_iucv_data(cpu);
-	cpu_notifier_register_done();
+
+	cpuhp_remove_state_nocalls(iucv_online);
+	cpuhp_remove_state(CPUHP_NET_IUCV_PREPARE);
 	root_device_unregister(iucv_root);
 	bus_unregister(&iucv_bus);
 	unregister_external_irq(EXT_IRQ_IUCV, iucv_external_interrupt);