| Message ID | 20140310203458.10746.59610.stgit@srivatsabhat.in.ibm.com (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Headers | show |
diff --git a/arch/ia64/kernel/topology.c b/arch/ia64/kernel/topology.c index ca69a5a..f295f9a 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; }
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> Cc: linux-ia64@vger.kernel.org Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> --- arch/ia64/kernel/topology.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html