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authorSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>2014-03-11 02:04:45 +0530
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2014-03-20 13:43:40 +0100
commiteff722b06bdd6de326894ea2353ec0eda3e5ed34 (patch)
tree32812f5ddeaa7cf23308caaabb0131305ec96346 /arch/ia64
parentf0bdb5e0c72b7347c867da539367138ad95c6b24 (diff)
ia64, salinfo: Fix 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 salinfo 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/salinfo.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/arch/ia64/kernel/salinfo.c b/arch/ia64/kernel/salinfo.c
index 960a396f5929..ee9719eebb1e 100644
--- a/arch/ia64/kernel/salinfo.c
+++ b/arch/ia64/kernel/salinfo.c
@@ -635,6 +635,8 @@ salinfo_init(void)
(void *)salinfo_entries[i].feature);
}
+ cpu_notifier_register_begin();
+
for (i = 0; i < ARRAY_SIZE(salinfo_log_name); i++) {
data = salinfo_data + i;
data->type = i;
@@ -669,7 +671,9 @@ salinfo_init(void)
salinfo_timer.function = &salinfo_timeout;
add_timer(&salinfo_timer);
- register_hotcpu_notifier(&salinfo_cpu_notifier);
+ __register_hotcpu_notifier(&salinfo_cpu_notifier);
+
+ cpu_notifier_register_done();
return 0;
}