[PATCH V2] Driver cpu: update online when cpu_up/down besides sysfs

[Neil Zhang]

The current per-cpu offline info won't be updated when we use
any other method besides sysfs to call cpu_up/down.
Thus the cpu/online can't reflect the real online status.

This patch is going to fix the issue introduced by commit
0902a9044fa5b7a0456ea4daacec2c2b3189ba8c (Driver core:
Use generic offline/online for CPU offline/online)

CC: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Tested-by: Dan Streetman <ddstreet@xxxxxxxx>
Signed-off-by: Neil Zhang <zhangwm@xxxxxxxxxxx>
---
 drivers/base/cpu.c |   25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 006b1bc..9d61824 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -418,10 +418,35 @@ static void __init cpu_dev_register_generic(void)
 #endif
 }
 
+static int device_hotplug_notifier(struct notifier_block *nfb,
+				      unsigned long action, void *hcpu)
+{
+	unsigned int cpu = (unsigned long)hcpu;
+	struct device *dev = get_cpu_device(cpu);
+	int ret;
+
+	switch (action & ~CPU_TASKS_FROZEN) {
+	case CPU_ONLINE:
+		dev->offline = false;
+		ret = NOTIFY_OK;
+		break;
+	case CPU_DYING:
+		dev->offline = true;
+		ret = NOTIFY_OK;
+		break;
+	default:
+		ret = NOTIFY_DONE;
+		break;
+	}
+
+	return ret;
+}
+
 void __init cpu_dev_init(void)
 {
 	if (subsys_system_register(&cpu_subsys, cpu_root_attr_groups))
 		panic("Failed to register CPU subsystem");
 
 	cpu_dev_register_generic();
+	cpu_notifier(device_hotplug_notifier, 0);
 }
-- 
1.7.9.5

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