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x86, intel, cacheinfo: Fix CPU hotplug callback registration

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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 intel cacheinfo code in x86 by using this latter form of callback
registration.

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 02:07:57 +05:30 committed by Rafael J. Wysocki
parent 047868ce29
commit 8c60ea1464
1 changed files with 8 additions and 5 deletions
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13
arch/x86/kernel/cpu/intel_cacheinfo.c
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@ -1225,21 +1225,24 @@ static struct notifier_block cacheinfo_cpu_notifier = {
static int __init cache_sysfs_init(void)
{
int i;
int i, err = 0;
if (num_cache_leaves == 0)
return 0;
cpu_notifier_register_begin();
for_each_online_cpu(i) {
int err;
struct device *dev = get_cpu_device(i);
err = cache_add_dev(dev);
if (err)
return err;
goto out;
}
register_hotcpu_notifier(&cacheinfo_cpu_notifier);
return 0;
__register_hotcpu_notifier(&cacheinfo_cpu_notifier);
out:
cpu_notifier_register_done();
return err;
}
device_initcall(cache_sysfs_init);