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authorSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>2014-03-11 02:05:10 +0530
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2014-03-20 13:43:41 +0100
commitf2e48a89053dea259d7f96cf0fd1cfc7c4b34d80 (patch)
tree1dd984a6502039c5ffe6e0e863a0c31ec98af9ee
parentf5a7d445ffb6b251dc41942ffe41f515e8d639a4 (diff)
downloadop-kernel-dev-f2e48a89053dea259d7f96cf0fd1cfc7c4b34d80.zip
op-kernel-dev-f2e48a89053dea259d7f96cf0fd1cfc7c4b34d80.tar.gz
ia64, err-inject: 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 error injection 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>
-rw-r--r--arch/ia64/kernel/err_inject.c15
1 files changed, 13 insertions, 2 deletions
diff --git a/arch/ia64/kernel/err_inject.c b/arch/ia64/kernel/err_inject.c
index f59c0b8..0c161ed 100644
--- a/arch/ia64/kernel/err_inject.c
+++ b/arch/ia64/kernel/err_inject.c
@@ -269,12 +269,17 @@ err_inject_init(void)
#ifdef ERR_INJ_DEBUG
printk(KERN_INFO "Enter error injection driver.\n");
#endif
+
+ cpu_notifier_register_begin();
+
for_each_online_cpu(i) {
err_inject_cpu_callback(&err_inject_cpu_notifier, CPU_ONLINE,
(void *)(long)i);
}
- register_hotcpu_notifier(&err_inject_cpu_notifier);
+ __register_hotcpu_notifier(&err_inject_cpu_notifier);
+
+ cpu_notifier_register_done();
return 0;
}
@@ -288,11 +293,17 @@ err_inject_exit(void)
#ifdef ERR_INJ_DEBUG
printk(KERN_INFO "Exit error injection driver.\n");
#endif
+
+ cpu_notifier_register_begin();
+
for_each_online_cpu(i) {
sys_dev = get_cpu_device(i);
sysfs_remove_group(&sys_dev->kobj, &err_inject_attr_group);
}
- unregister_hotcpu_notifier(&err_inject_cpu_notifier);
+
+ __unregister_hotcpu_notifier(&err_inject_cpu_notifier);
+
+ cpu_notifier_register_done();
}
module_init(err_inject_init);
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