x86: don't call mce_create_device on CPU_UP_PREPARE

Fix regression introduced with d435d862baca3e25e5eec236762a43251b1e7ffc
("cpu hotplug: mce: fix cpu hotplug error handling").

A CPU which was not brought up during boot (using maxcpus and
additional_cpus parameters) couldn't be onlined anymore.  For such a CPU it
seemed that MCE was not supported during CPU_UP_PREPARE-time which caused
mce_cpu_callback to return NOTIFY_BAD to notifier_call_chain.  To fix this
we:

 - call mce_create_device for CPU_ONLINE event (instead of CPU_UP_PREPARE),
 - avoid mce_remove_device() for the CPU that is not correctly initialized
   by mce_create_device() failure,
 - make mce_cpu_callback always return NOTIFY_OK for CPU_ONLINE event.
   Because CPU_ONLINE callback return value is always ignored.

[akinobu.mita@gmail.com: avoid mce_remove_device() for not initialized device]
[akinobu.mita@gmail.com: make mce_cpu_callback always return NOTIFY_OK]
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/x86/kernel/cpu/mcheck/mce_64.c b/arch/x86/kernel/cpu/mcheck/mce_64.c
index b9f802e35209187a45045b3576027f9f0ac9de25..447b351f1f2aefcb07ea7b68b6456f50d20f5336 100644 (file)
--- a/arch/x86/kernel/cpu/mcheck/mce_64.c
+++ b/arch/x86/kernel/cpu/mcheck/mce_64.c
@@ -802,6 +802,8 @@ static struct sysdev_attribute *mce_attributes[] = {
        NULL
 };
 
+static cpumask_t mce_device_initialized = CPU_MASK_NONE;
+
 /* Per cpu sysdev init.  All of the cpus still share the same ctl bank */
 static __cpuinit int mce_create_device(unsigned int cpu)
 {
@@ -825,6 +827,7 @@ static __cpuinit int mce_create_device(unsigned int cpu)
                if (err)
                        goto error;
        }
+       cpu_set(cpu, mce_device_initialized);
 
        return 0;
 error:
@@ -841,10 +844,14 @@ static void mce_remove_device(unsigned int cpu)
 {
        int i;
 
+       if (!cpu_isset(cpu, mce_device_initialized))
+               return;
+
        for (i = 0; mce_attributes[i]; i++)
                sysdev_remove_file(&per_cpu(device_mce,cpu),
                        mce_attributes[i]);
        sysdev_unregister(&per_cpu(device_mce,cpu));
+       cpu_clear(cpu, mce_device_initialized);
 }
 
 /* Get notified when a cpu comes on/off. Be hotplug friendly. */
@@ -852,21 +859,18 @@ static int
 mce_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:
-       case CPU_UP_PREPARE_FROZEN:
-               err = mce_create_device(cpu);
+       case CPU_ONLINE:
+       case CPU_ONLINE_FROZEN:
+               mce_create_device(cpu);
                break;
-       case CPU_UP_CANCELED:
-       case CPU_UP_CANCELED_FROZEN:
        case CPU_DEAD:
        case CPU_DEAD_FROZEN:
                mce_remove_device(cpu);
                break;
        }
-       return err ? NOTIFY_BAD : NOTIFY_OK;
+       return NOTIFY_OK;
 }
 
 static struct notifier_block mce_cpu_notifier = {