[PATCH 1/1] Revert "hwmon: (coretemp) Convert to hotplug state machine"

[Janusz Krzysztofik]

This reverts commit e00ca5df37adc68052ea699cbd010ee4e19e39e4.
---
 drivers/hwmon/coretemp.c | 85 +++++++++++++++++++++++++++++-----------
 1 file changed, 63 insertions(+), 22 deletions(-)

diff --git a/drivers/hwmon/coretemp.c b/drivers/hwmon/coretemp.c
index ccf0af5b988a7..169f03f50eef8 100644
--- a/drivers/hwmon/coretemp.c
+++ b/drivers/hwmon/coretemp.c
@@ -586,7 +586,7 @@ static struct platform_device *coretemp_device_add(unsigned int cpu)
 	return pdev;
 }
 
-static int coretemp_cpu_online(unsigned int cpu)
+static void get_core_online(unsigned int cpu)
 {
 	struct platform_device *pdev = coretemp_get_pdev(cpu);
 	struct cpuinfo_x86 *c = &cpu_data(cpu);
@@ -605,12 +605,12 @@ static int coretemp_cpu_online(unsigned int cpu)
 	 * without thermal sensors will be filtered out.
 	 */
 	if (!cpu_has(c, X86_FEATURE_DTHERM))
-		return -ENODEV;
+		return;
 
 	if (!pdev) {
 		/* Check the microcode version of the CPU */
 		if (chk_ucode_version(cpu))
-			return -EINVAL;
+			return;
 
 		/*
 		 * Alright, we have DTS support.
@@ -620,7 +620,7 @@ static int coretemp_cpu_online(unsigned int cpu)
 		 */
 		pdev = coretemp_device_add(cpu);
 		if (IS_ERR(pdev))
-			return PTR_ERR(pdev);
+			return;
 
 		/*
 		 * Check whether pkgtemp support is available.
@@ -639,10 +639,9 @@ static int coretemp_cpu_online(unsigned int cpu)
 		coretemp_add_core(pdev, cpu, 0);
 
 	cpumask_set_cpu(cpu, &pdata->cpumask);
-	return 0;
 }
 
-static int coretemp_cpu_offline(unsigned int cpu)
+static void put_core_offline(unsigned int cpu)
 {
 	struct platform_device *pdev = coretemp_get_pdev(cpu);
 	struct platform_data *pd;
@@ -658,12 +657,12 @@ static int coretemp_cpu_offline(unsigned int cpu)
 
 	/* If the physical CPU device does not exist, just return */
 	if (!pdev)
-		return 0;
+		return;
 
 	/* The core id is too big, just return */
 	indx = TO_ATTR_NO(cpu);
 	if (indx > MAX_CORE_DATA - 1)
-		return 0;
+		return;
 
 	pd = platform_get_drvdata(pdev);
 	tdata = pd->core_data[indx];
@@ -692,7 +691,7 @@ static int coretemp_cpu_offline(unsigned int cpu)
 	if (cpumask_empty(&pd->cpumask)) {
 		zone_devices[topology_logical_die_id(cpu)] = NULL;
 		platform_device_unregister(pdev);
-		return 0;
+		return;
 	}
 
 	/*
@@ -706,19 +705,38 @@ static int coretemp_cpu_offline(unsigned int cpu)
 		tdata->cpu = target;
 		mutex_unlock(&tdata->update_lock);
 	}
-	return 0;
 }
+
+static int coretemp_cpu_callback(struct notifier_block *nfb,
+				 unsigned long action, void *hcpu)
+{
+	unsigned int cpu = (unsigned long) hcpu;
+
+	switch (action) {
+	case CPU_ONLINE:
+	case CPU_DOWN_FAILED:
+		get_core_online(cpu);
+		break;
+	case CPU_DOWN_PREPARE:
+		put_core_offline(cpu);
+		break;
+	}
+	return NOTIFY_OK;
+}
+
+static struct notifier_block coretemp_cpu_notifier __refdata = {
+	.notifier_call = coretemp_cpu_callback,
+};
+
 static const struct x86_cpu_id __initconst coretemp_ids[] = {
 	X86_MATCH_VENDOR_FEATURE(INTEL, X86_FEATURE_DTHERM, NULL),
 	{}
 };
 MODULE_DEVICE_TABLE(x86cpu, coretemp_ids);
 
-static enum cpuhp_state coretemp_hp_online;
-
 static int __init coretemp_init(void)
 {
-	int err;
+	int i, err;
 
 	/*
 	 * CPUID.06H.EAX[0] indicates whether the CPU has thermal
@@ -738,29 +756,52 @@ static int __init coretemp_init(void)
 	if (err)
 		goto outzone;
 
-	err = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "hwmon/coretemp:online",
-				coretemp_cpu_online, coretemp_cpu_offline);
-	if (err < 0)
-		goto outdrv;
-	coretemp_hp_online = err;
+	cpu_notifier_register_begin();
+	for_each_online_cpu(i)
+		get_core_online(i);
+
+#ifndef CONFIG_HOTPLUG_CPU
+	if (list_empty(&pdev_list)) {
+		cpu_notifier_register_done();
+		err = -ENODEV;
+		goto exit_driver_unreg;
+	}
+#endif
+
+	__register_hotcpu_notifier(&coretemp_cpu_notifier);
+	cpu_notifier_register_done();
 	return 0;
 
-outdrv:
+#ifndef CONFIG_HOTPLUG_CPU
+exit_driver_unreg:
 	platform_driver_unregister(&coretemp_driver);
+#endif
 outzone:
 	kfree(zone_devices);
 	return err;
 }
-module_init(coretemp_init)
 
 static void __exit coretemp_exit(void)
 {
-	cpuhp_remove_state(coretemp_hp_online);
+	struct pdev_entry *p, *n;
+
+	cpu_notifier_register_begin();
+	__unregister_hotcpu_notifier(&coretemp_cpu_notifier);
+	mutex_lock(&pdev_list_mutex);
+	list_for_each_entry_safe(p, n, &pdev_list, list) {
+		platform_device_unregister(p->pdev);
+		list_del(&p->list);
+		kfree(p);
+	}
+	mutex_unlock(&pdev_list_mutex);
+	cpu_notifier_register_done();
 	platform_driver_unregister(&coretemp_driver);
 	kfree(zone_devices);
 }
-module_exit(coretemp_exit)
 
 MODULE_AUTHOR("Rudolf Marek <r.marek at assembler.cz>");
 MODULE_DESCRIPTION("Intel Core temperature monitor");
 MODULE_LICENSE("GPL");
+
+module_init(coretemp_init)
+module_exit(coretemp_exit)
-- 
2.25.1