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[tip:smp/hotplug] x86/msr: Convert to hotplug state machine

From tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com>
Newsgroups linux.kernel
Subject [tip:smp/hotplug] x86/msr: Convert to hotplug state machine
Date 2016-11-21 16:50 +0100
Message-ID <sFZ0Z-2ZM-29@gated-at.bofh.it> (permalink)
References <sEzV0-4p4-23@gated-at.bofh.it>
Organization linux.* mail to news gateway

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Commit-ID:  216a5d1b866538a021af00bfb7c5dcd1da8ff884
Gitweb:     http://git.kernel.org/tip/216a5d1b866538a021af00bfb7c5dcd1da8ff884
Author:     Sebastian Andrzej Siewior <bigeasy@linutronix.de>
AuthorDate: Thu, 17 Nov 2016 19:35:24 +0100
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Mon, 21 Nov 2016 16:37:05 +0100

x86/msr: Convert to hotplug state machine

Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs.

Move the callbacks to online/offline as there is no point in having the
files around before the cpu is online and until its completely gone.

[ tglx: Move the callbacks to online/offline ]

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: rt@linuxtronix.de
Link: http://lkml.kernel.org/r/20161117183541.8588-4-bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

---
 arch/x86/kernel/msr.c | 66 +++++++++++----------------------------------------
 1 file changed, 14 insertions(+), 52 deletions(-)

diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c
index 7f3550a..7935815 100644
--- a/arch/x86/kernel/msr.c
+++ b/arch/x86/kernel/msr.c
@@ -44,6 +44,7 @@
 #include <asm/msr.h>
 
 static struct class *msr_class;
+static enum cpuhp_state cpuhp_msr_state;
 
 static ssize_t msr_read(struct file *file, char __user *buf,
 			size_t count, loff_t *ppos)
@@ -180,7 +181,7 @@ static const struct file_operations msr_fops = {
 	.compat_ioctl = msr_ioctl,
 };
 
-static int msr_device_create(int cpu)
+static int msr_device_create(unsigned int cpu)
 {
 	struct device *dev;
 
@@ -189,34 +190,12 @@ static int msr_device_create(int cpu)
 	return PTR_ERR_OR_ZERO(dev);
 }
 
-static void msr_device_destroy(int cpu)
+static int msr_device_destroy(unsigned int cpu)
 {
 	device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu));
+	return 0;
 }
 
-static int msr_class_cpu_callback(struct notifier_block *nfb,
-				  unsigned long action, void *hcpu)
-{
-	unsigned int cpu = (unsigned long)hcpu;
-	int err = 0;
-
-	switch (action) {
-	case CPU_UP_PREPARE:
-		err = msr_device_create(cpu);
-		break;
-	case CPU_UP_CANCELED:
-	case CPU_UP_CANCELED_FROZEN:
-	case CPU_DEAD:
-		msr_device_destroy(cpu);
-		break;
-	}
-	return notifier_from_errno(err);
-}
-
-static struct notifier_block __refdata msr_class_cpu_notifier = {
-	.notifier_call = msr_class_cpu_callback,
-};
-
 static char *msr_devnode(struct device *dev, umode_t *mode)
 {
 	return kasprintf(GFP_KERNEL, "cpu/%u/msr", MINOR(dev->devt));
@@ -224,8 +203,7 @@ static char *msr_devnode(struct device *dev, umode_t *mode)
 
 static int __init msr_init(void)
 {
-	int i, err = 0;
-	i = 0;
+	int err;
 
 	if (__register_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr", &msr_fops)) {
 		pr_err("unable to get major %d for msr\n", MSR_MAJOR);
@@ -239,44 +217,28 @@ static int __init msr_init(void)
 	}
 	msr_class->devnode = msr_devnode;
 
-	cpu_notifier_register_begin();
-	for_each_online_cpu(i) {
-		err = msr_device_create(i);
-		if (err != 0)
-			goto out_class;
-	}
-	__register_hotcpu_notifier(&msr_class_cpu_notifier);
-	cpu_notifier_register_done();
-
-	err = 0;
-	goto out;
+	err  = cpuhp_setup_state(CPUHP_X86_MSR_PREPARE, "x86/msr:online",
+				 msr_device_create, msr_device_destroy);
+	if (err < 0)
+		goto out_class;
+	cpuhp_msr_state = err;
+	return 0;
 
 out_class:
-	i = 0;
-	for_each_online_cpu(i)
-		msr_device_destroy(i);
-	cpu_notifier_register_done();
+	cpuhp_remove_state(cpuhp_msr_state);
 	class_destroy(msr_class);
 out_chrdev:
 	__unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr");
-out:
 	return err;
 }
+module_init(msr_init);
 
 static void __exit msr_exit(void)
 {
-	int cpu = 0;
-
-	cpu_notifier_register_begin();
-	for_each_online_cpu(cpu)
-		msr_device_destroy(cpu);
+	cpuhp_remove_state(cpuhp_msr_state);
 	class_destroy(msr_class);
 	__unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr");
-	__unregister_hotcpu_notifier(&msr_class_cpu_notifier);
-	cpu_notifier_register_done();
 }
-
-module_init(msr_init);
 module_exit(msr_exit)
 
 MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>");

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cpu hotplug: convert more drivers (batch #5) Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-17 19:40 +0100
  [PATCH 12/20] net/iucv: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-17 19:40 +0100
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    [tip:smp/hotplug] net/iucv: Convert to hotplug state machine tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-11-23 00:20 +0100
    Re: [PATCH 12/20] net/iucv: Convert to hotplug state machine Ursula Braun <ubraun@linux.vnet.ibm.com> - 2016-11-23 20:40 +0100
      Re: [PATCH 12/20] net/iucv: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-24 10:20 +0100
        [PATCH 12/20 v2] net/iucv: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-24 15:20 +0100
          [PATCH] net/iucv: use explicit clean up labels in iucv_init() Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-24 17:20 +0100
            [tip:smp/hotplug] net/iucv: Use explicit clean up labels in  iucv_init() tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-11-24 21:00 +0100
  [PATCH 09/20] powercap/intel rapl: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-17 19:40 +0100
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  [PATCH 19/20] x86/oprofile/nmi: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-17 19:40 +0100
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  [PATCH 14/20] arm/bL_switcher: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-17 19:40 +0100
    [tip:smp/hotplug] arm/bL_switcher: Convert to hotplug state machine tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-11-21 17:00 +0100
    [tip:smp/hotplug] arm/bL_switcher: Convert to hotplug state machine tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-11-22 23:50 +0100
  [PATCH 13/20] sched/nohz: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-17 19:40 +0100
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  [PATCH 16/20] powerpc/sysfs: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-17 19:40 +0100
    [tip:smp/hotplug] powerpc/sysfs: Convert to hotplug state machine tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-11-21 17:00 +0100
    [tip:smp/hotplug] powerpc/sysfs: Convert to hotplug state machine tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-11-22 23:50 +0100
  [PATCH 10/20] powercap/intel_rapl: Cleanup duplicated init code Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-17 19:50 +0100
    [tip:smp/hotplug] powercap/intel_rapl: Cleanup duplicated init code tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2016-11-21 17:00 +0100
  [PATCH 01/20] x86/mce/therm_throt: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-17 19:50 +0100
    [tip:smp/hotplug] x86/mce/therm_throt: Convert to hotplug state  machine tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-11-21 16:50 +0100
    [tip:smp/hotplug] x86/mce/therm_throt: Convert to hotplug state  machine tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-11-22 23:50 +0100
  [PATCH 07/20] pci/xgene-msi: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-17 19:50 +0100
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  [PATCH 06/20] hwmon/via-cputemp: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-17 19:50 +0100
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    Re: [PATCH 06/20] hwmon/via-cputemp: Convert to hotplug state machine Guenter Roeck <linux@roeck-us.net> - 2016-11-23 16:40 +0100
  [PATCH 05/20] hwmon/via-cputemp: Remove pointless CPU check on each CPU Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-17 19:50 +0100
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        Re: [05/20] hwmon/via-cputemp: Remove pointless CPU check on each CPU Guenter Roeck <linux@roeck-us.net> - 2016-11-20 05:00 +0100
          Re: [05/20] hwmon/via-cputemp: Remove pointless CPU check on each CPU Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-20 21:40 +0100
  [PATCH 08/20] powercap/intel_rapl: Add missing domain data update on hotplug Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-17 19:50 +0100
    [tip:smp/hotplug] powercap/intel_rapl: Add missing domain data  update on hotplug tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2016-11-21 16:50 +0100
  [PATCH 03/20] x86/msr: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-17 19:50 +0100
    [tip:smp/hotplug] x86/msr: Convert to hotplug state machine tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-11-21 16:50 +0100
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