> [PATCH] x86: fix cpu hotplug regression (don't call mce_create_device on CPU_UP_PREPARE)
>
> Fix regression introduced with d435d862baca3e25e5eec236762a43251b1e7ffc
> ("cpu hotplug: mce: fix cpu hotplug error handling").
>
> For CPUs not brought up during boot (using maxcpus and additional_cpus
> parameters) we don't know whether mce is supported or not at "CPU_UP_PREPARE"-time.
> Thus mce_cpu_callback should be called after the CPU is online.
Thank you for finding and fixing the problem.
I added two fixes to your patch:
- Avoid mce_remove_device() for the CPU that is not correctly initialized
by mce_create_device() failure.
- make CPU_ONLINE callback always return NOTIFY_OK.
Because CPU_ONLINE callback return value is always ignored.
> Signed-off-by: Andreas Herrmann <[email protected]>
[[email protected]: make CPU_ONLINE callback always return NOTIFY_OK]
[[email protected]: avoid mce_remove_device() for not initialized device]
Signed-off-by: Akinobu Mita <[email protected]>
---
arch/x86/kernel/cpu/mcheck/mce_64.c | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)
Index: 2.6-git/arch/x86/kernel/cpu/mcheck/mce_64.c
===================================================================
--- 2.6-git.orig/arch/x86/kernel/cpu/mcheck/mce_64.c
+++ 2.6-git/arch/x86/kernel/cpu/mcheck/mce_64.c
@@ -802,6 +802,8 @@ static struct sysdev_attribute *mce_attr
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(u
if (err)
goto error;
}
+ cpu_set(cpu, mce_device_initialized);
return 0;
error:
@@ -841,10 +844,14 @@ static void mce_remove_device(unsigned i
{
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 = {
-
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