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x86, mce: Fix CPU hotplug callback registration 

Subsystems that want to register CPU hotplug callbacks, as well as perform
initialization for the CPUs that are already online, often do it as shown
below:

	get_online_cpus();

	for_each_online_cpu(cpu)
		init_cpu(cpu);

	register_cpu_notifier(&foobar_cpu_notifier);

	put_online_cpus();

This is wrong, since it is prone to ABBA deadlocks involving the
cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
with CPU hotplug operations).

Instead, the correct and race-free way of performing the callback
registration is:

	cpu_notifier_register_begin();

	for_each_online_cpu(cpu)
		init_cpu(cpu);

	/* Note the use of the double underscored version of the API */
	__register_cpu_notifier(&foobar_cpu_notifier);

	cpu_notifier_register_done();

Fix the mce code in x86 by using this latter form of callback registration.

Cc: Tony Luck <tony.luck@intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Srivatsa S. Bhat 2014-03-11 02:07:04 +05:30 committed by Rafael J. Wysocki
parent 2c666adacc
commit 82a8f131aa
1 changed files with 6 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
arch/x86/kernel/cpu/mcheck/mce.c
View File

@ -2434,14 +2434,18 @@ static __init int mcheck_init_device(void)
if (err) if (err)
return err; return err;
cpu_notifier_register_begin();
for_each_online_cpu(i) { for_each_online_cpu(i) {
err = mce_device_create(i); err = mce_device_create(i);
if (err) if (err) {
cpu_notifier_register_done();
return err; return err;
} }
}
register_syscore_ops(&mce_syscore_ops); register_syscore_ops(&mce_syscore_ops);
register_hotcpu_notifier(&mce_cpu_notifier); __register_hotcpu_notifier(&mce_cpu_notifier);
cpu_notifier_register_done();
/* register character device /dev/mcelog */ /* register character device /dev/mcelog */
misc_register(&mce_chrdev_device); misc_register(&mce_chrdev_device);