linux-kernel - [tip:smp/hotplug] cpufreq: Use cpuhp_setup_state_nocalls

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Date:   Fri, 26 May 2017 01:36:09 -0700
From:   tip-bot for Sebastian Andrzej Siewior <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     paulmck@...ux.vnet.ibm.com, bigeasy@...utronix.de,
        rostedt@...dmis.org, peterz@...radead.org, viresh.kumar@...aro.org,
        hpa@...or.com, linux-kernel@...r.kernel.org, mingo@...nel.org,
        rafael.j.wysocki@...el.com, tglx@...utronix.de
Subject: [tip:smp/hotplug] cpufreq: Use
 cpuhp_setup_state_nocalls_cpuslocked()

Commit-ID:  a92551e41d5a7b563ae440496bc5ca19d205231d
Gitweb:     http://git.kernel.org/tip/a92551e41d5a7b563ae440496bc5ca19d205231d
Author:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
AuthorDate: Wed, 24 May 2017 10:15:20 +0200
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Fri, 26 May 2017 10:10:38 +0200

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

---
 drivers/cpufreq/cpufreq.c | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 0e3f649..6001369 100644
--- 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;
 }