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authorSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>2014-03-11 00:34:58 +0400
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2014-03-20 16:43:40 +0400
commitf5a7d445ffb6b251dc41942ffe41f515e8d639a4 (patch)
tree821f3304e880e4cd48fef4793ea5a02a7185d07b /arch/ia64
parent9f37bca9a9e97fcd7589492aba7b8a5310026c47 (diff)
downloadlinux-f5a7d445ffb6b251dc41942ffe41f515e8d639a4.tar.xz
ia64, topology: 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 topology code in ia64 by using this latter form of callback registration. Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> 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 'arch/ia64')
-rw-r--r--arch/ia64/kernel/topology.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/arch/ia64/kernel/topology.c b/arch/ia64/kernel/topology.c
index ca69a5a96dcc..f295f9abba4b 100644
--- a/arch/ia64/kernel/topology.c
+++ b/arch/ia64/kernel/topology.c
@@ -454,12 +454,16 @@ static int __init cache_sysfs_init(void)
{
int i;
+ cpu_notifier_register_begin();
+
for_each_online_cpu(i) {
struct device *sys_dev = get_cpu_device((unsigned int)i);
cache_add_dev(sys_dev);
}
- register_hotcpu_notifier(&cache_cpu_notifier);
+ __register_hotcpu_notifier(&cache_cpu_notifier);
+
+ cpu_notifier_register_done();
return 0;
}