When we suspend a laptop we offline all but one processor. But
the mce code registers on a notify chain so it can clean up
some sysfs entries. Part of that code calls device_unregister()
which will fire kobject_uevent() which might wake up some user
code that is watching for such things.
Patch below from Aiden Park works around the issue by avoiding
the device_unregister()/device_register() by just keeping track
of the original device registrations.
1) Is there a better way to avoid the kobject_uevent()?
2) What user code actually uses all these sysfs files?
Some test code in mcelog(8) uses:
/sys/devices/system/machinecheck/machinecheck0/trigger
Some code in mce-test package adjusts
/sys/devices/system/machinecheck/machinecheck0/tolerant
But neither of these make use of all the per-cpu instances
created/destroyed on every suspend/resume (or logical processor
offline). Should we just move these out of per-cpu directories
and scrap this whole block of code?
3) checkpatch isn't happy about use of NR_CPUS I suspect the
usage here warrants for_each_possible_cpu()
-Tony Luck
---
diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
old mode 100644
new mode 100755
index 68317c80de7f..e49302f24ce5
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -113,6 +113,8 @@ static DEFINE_PER_CPU(struct work_struct, mce_work);
static void (*quirk_no_way_out)(int bank, struct mce *m, struct pt_regs *regs);
+static struct device *mce_devices[NR_CPUS];
+
/*
* CPU/chipset specific EDAC code can register a notifier call here to print
* MCE errors in a human-readable form.
@@ -2060,7 +2062,18 @@ static int mce_syscore_suspend(void)
static void mce_syscore_shutdown(void)
{
+ int i = 0;
+ struct device *dev;
+
mce_disable_error_reporting();
+
+ for (i = 0; i < NR_CPUS; i++) {
+ dev = mce_devices[i];
+ if (dev) {
+ device_unregister(dev);
+ mce_devices[i] = NULL;
+ }
+ }
}
/*
@@ -2272,23 +2285,27 @@ static void mce_device_release(struct device *dev)
static int mce_device_create(unsigned int cpu)
{
struct device *dev;
- int err;
+ int err = 0;
int i, j;
if (!mce_available(&boot_cpu_data))
return -EIO;
- dev = kzalloc(sizeof *dev, GFP_KERNEL);
- if (!dev)
- return -ENOMEM;
- dev->id = cpu;
- dev->bus = &mce_subsys;
- dev->release = &mce_device_release;
+ dev = mce_devices[cpu];
+ if (!dev) {
+ dev = kzalloc(sizeof *dev, GFP_KERNEL);
+ if (!dev)
+ return -ENOMEM;
+ dev->id = cpu;
+ dev->bus = &mce_subsys;
+ dev->release = &mce_device_release;
- err = device_register(dev);
- if (err) {
- put_device(dev);
- return err;
+ err = device_register(dev);
+ if (err) {
+ put_device(dev);
+ return err;
+ }
+ mce_devices[cpu] = dev;
}
for (i = 0; mce_device_attrs[i]; i++) {
@@ -2313,6 +2330,7 @@ error:
device_remove_file(dev, mce_device_attrs[i]);
device_unregister(dev);
+ mce_devices[cpu] = NULL;
return err;
}
@@ -2331,7 +2349,6 @@ static void mce_device_remove(unsigned int cpu)
for (i = 0; i < mca_cfg.banks; i++)
device_remove_file(dev, &mce_banks[i].attr);
- device_unregister(dev);
cpumask_clear_cpu(cpu, mce_device_initialized);
per_cpu(mce_device, cpu) = NULL;
}
@@ -2450,6 +2467,7 @@ static __init int mcheck_init_device(void)
cpu_notifier_register_begin();
for_each_online_cpu(i) {
+ mce_devices[i] = NULL;
err = mce_device_create(i);
if (err) {
cpu_notifier_register_done();
--
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