Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-11-17 01:22:07 +00:00
Code Issues Packages Projects Releases Wiki Activity

x86, intel, cacheinfo: Fix CPU hotplug callback registration

Browse Source 
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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
arch/x86/kernel/cpu/intel_cacheinfo.c
View File

@ -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);