cpufreq: Use cpuhp_setup_state_nocalls_cpuslocked()

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 <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: linux-pm@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170524081547.731628408@linutronix.de

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 0e3f6496524d92c7c1717d8d2259684952d7acb8..6001369f9aeb4d2b9e1b90401bb399a75d9cb406 100644 (file)
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -887,7 +887,7 @@ static ssize_t store(struct kobject *kobj, struct attribute *attr,
        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 *kobj, struct attribute *attr,
                up_write(&policy->rwsem);
        }
 
-       put_online_cpus();
+       cpus_read_unlock();
 
        return ret;
 }
@@ -2441,7 +2441,7 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
        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 cpufreq_driver *driver_data)
                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 @@ err_null_driver:
        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 cpufreq_driver *driver)
        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;
 }