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Subject[tip:smp/hotplug] cpufreq: Use cpuhp_setup_state_nocalls_cpuslocked()
Commit-ID:  6d7d2f1f9e6e0c2d6fb9de82ad5fbc3aed115829
Gitweb: http://git.kernel.org/tip/6d7d2f1f9e6e0c2d6fb9de82ad5fbc3aed115829
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
AuthorDate: Tue, 18 Apr 2017 19:04:48 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Thu, 20 Apr 2017 13:08:52 +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.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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/20170418170552.865966021@linutronix.de

---
drivers/cpufreq/cpufreq.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 0e3f649..67ef7ce 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -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;
@@ -2519,7 +2520,7 @@ int cpufreq_unregister_driver(struct cpufreq_driver *driver)
get_online_cpus();
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);

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