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authorSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>2014-03-11 02:10:30 +0530
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2014-03-20 13:43:46 +0100
commit07494d547e92bde6857522d2a92ff70896aecadb (patch)
tree6b1d929b0a3902c9112217a8cad489521a249ce1 /drivers/idle
parent8daa127f4e857427c66f365f650dda90f459aa54 (diff)
downloadlinux-07494d547e92bde6857522d2a92ff70896aecadb.tar.bz2
intel-idle: 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 intel-idle code by using this latter form of callback registration. Cc: Len Brown <lenb@kernel.org> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/idle')
-rw-r--r--drivers/idle/intel_idle.c12
1 files changed, 10 insertions, 2 deletions
diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index 8e1939f564f4..51493ed4643b 100644
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -681,14 +681,19 @@ static int __init intel_idle_init(void)
if (intel_idle_cpuidle_devices == NULL)
return -ENOMEM;
+ cpu_notifier_register_begin();
+
for_each_online_cpu(i) {
retval = intel_idle_cpu_init(i);
if (retval) {
+ cpu_notifier_register_done();
cpuidle_unregister_driver(&intel_idle_driver);
return retval;
}
}
- register_cpu_notifier(&cpu_hotplug_notifier);
+ __register_cpu_notifier(&cpu_hotplug_notifier);
+
+ cpu_notifier_register_done();
return 0;
}
@@ -698,10 +703,13 @@ static void __exit intel_idle_exit(void)
intel_idle_cpuidle_devices_uninit();
cpuidle_unregister_driver(&intel_idle_driver);
+ cpu_notifier_register_begin();
if (lapic_timer_reliable_states != LAPIC_TIMER_ALWAYS_RELIABLE)
on_each_cpu(__setup_broadcast_timer, (void *)false, 1);
- unregister_cpu_notifier(&cpu_hotplug_notifier);
+ __unregister_cpu_notifier(&cpu_hotplug_notifier);
+
+ cpu_notifier_register_done();
return;
}