On Wed, Feb 05, 2014 at 04:44:31PM -0800, Guenter Roeck wrote: > On Thu, Feb 06, 2014 at 03:42:19AM +0530, Srivatsa S. Bhat wrote: > > 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_maps_update_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_maps_update_done(); > > > > > > Fix the hwmon via-cputemp code by using this latter form of callback > > registration. > > > > Cc: Jean Delvare <jdelvare@xxxxxxx> > > Cc: Guenter Roeck <linux@xxxxxxxxxxxx> > > Cc: lm-sensors@xxxxxxxxxxxxxx > > Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx> > > Applied. > Same here ... Acked-by: Guenter Roeck <linux@xxxxxxxxxxxx> _______________________________________________ lm-sensors mailing list lm-sensors@xxxxxxxxxxxxxx http://lists.lm-sensors.org/mailman/listinfo/lm-sensors
