From: Sebastian Andrzej Siewior cpufreq holds get_online_cpus() while invoking cpuhp_setup_state_nocalls() to make subsys_interface_register() and the registration of hotplug calls atomic versus cpu hotplug. cpuhp_setup_state_nocalls() invokes get_online_cpus() as well. This is correct, but prevents the conversion of the hotplug locking to a percpu rwsem. Use cpuhp_setup/remove_state_nocalls_cpuslocked() to avoid the nested call. Convert *_online_cpus() to the new interfaces while at it. Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Thomas Gleixner Acked-by: "Rafael J. Wysocki" Acked-by: Viresh Kumar Cc: linux-pm@vger.kernel.org Cc: Peter Zijlstra Cc: Steven Rostedt --- drivers/cpufreq/cpufreq.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -887,7 +887,7 @@ static ssize_t store(struct kobject *kob struct freq_attr *fattr = to_attr(attr); ssize_t ret = -EINVAL; - get_online_cpus(); + cpus_read_lock(); if (cpu_online(policy->cpu)) { down_write(&policy->rwsem); @@ -895,7 +895,7 @@ static ssize_t store(struct kobject *kob up_write(&policy->rwsem); } - put_online_cpus(); + cpus_read_unlock(); return ret; } @@ -2441,7 +2441,7 @@ int cpufreq_register_driver(struct cpufr pr_debug("trying to register driver %s\n", driver_data->name); /* Protect against concurrent CPU online/offline. */ - get_online_cpus(); + cpus_read_lock(); write_lock_irqsave(&cpufreq_driver_lock, flags); if (cpufreq_driver) { @@ -2473,9 +2473,10 @@ int cpufreq_register_driver(struct cpufr goto err_if_unreg; } - ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "cpufreq:online", - cpuhp_cpufreq_online, - cpuhp_cpufreq_offline); + ret = cpuhp_setup_state_nocalls_cpuslocked(CPUHP_AP_ONLINE_DYN, + "cpufreq:online", + cpuhp_cpufreq_online, + cpuhp_cpufreq_offline); if (ret < 0) goto err_if_unreg; hp_online = ret; @@ -2493,7 +2494,7 @@ int cpufreq_register_driver(struct cpufr cpufreq_driver = NULL; write_unlock_irqrestore(&cpufreq_driver_lock, flags); out: - put_online_cpus(); + cpus_read_unlock(); return ret; } EXPORT_SYMBOL_GPL(cpufreq_register_driver); @@ -2516,17 +2517,17 @@ int cpufreq_unregister_driver(struct cpu pr_debug("unregistering driver %s\n", driver->name); /* Protect against concurrent cpu hotplug */ - get_online_cpus(); + cpus_read_lock(); subsys_interface_unregister(&cpufreq_interface); remove_boost_sysfs_file(); - cpuhp_remove_state_nocalls(hp_online); + cpuhp_remove_state_nocalls_cpuslocked(hp_online); write_lock_irqsave(&cpufreq_driver_lock, flags); cpufreq_driver = NULL; write_unlock_irqrestore(&cpufreq_driver_lock, flags); - put_online_cpus(); + cpus_read_unlock(); return 0; }