[patch 06/20] cpufreq: Use cpuhp_setup_state_nocalls_locked()

[patch 06/20] cpufreq: Use cpuhp_setup_state_nocalls_locked()

[Thomas Gleixner]

[-- Attachment #1: cpufreq-Use-cpuhp_setup_state_nocalls_locked.patch --]
[-- Type: text/plain, Size: 1599 bytes --]

From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

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_state_nocalls_locked() to avoid the nested call.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: linux-pm@vger.kernel.org

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

--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -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_locked(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 cpu
 	get_online_cpus();
 	subsys_interface_unregister(&cpufreq_interface);
 	remove_boost_sysfs_file();
-	cpuhp_remove_state_nocalls(hp_online);
+	cpuhp_remove_state_nocalls_locked(hp_online);
 
 	write_lock_irqsave(&cpufreq_driver_lock, flags);
 

Re: [patch 06/20] cpufreq: Use cpuhp_setup_state_nocalls_locked()

[Rafael J. Wysocki]

On Sat, Apr 15, 2017 at 7:01 PM, Thomas Gleixner <tglx@linutronix.de> wrote:
> From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
>
> 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_state_nocalls_locked() to avoid the nested call.
>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
> Cc: Viresh Kumar <viresh.kumar@linaro.org>
> Cc: linux-pm@vger.kernel.org

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

>
> ---
>  drivers/cpufreq/cpufreq.c |    9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
>
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -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_locked(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 cpu
>         get_online_cpus();
>         subsys_interface_unregister(&cpufreq_interface);
>         remove_boost_sysfs_file();
> -       cpuhp_remove_state_nocalls(hp_online);
> +       cpuhp_remove_state_nocalls_locked(hp_online);
>
>         write_lock_irqsave(&cpufreq_driver_lock, flags);
>
>
>

Re: [patch 06/20] cpufreq: Use cpuhp_setup_state_nocalls_locked()

[Viresh Kumar]

On 15-04-17, 19:01, Thomas Gleixner wrote:
> From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> 
> 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_state_nocalls_locked() to avoid the nested call.
> 
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
> Cc: Viresh Kumar <viresh.kumar@linaro.org>
> Cc: linux-pm@vger.kernel.org
> 
> ---
>  drivers/cpufreq/cpufreq.c |    9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -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_locked(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 cpu
>  	get_online_cpus();
>  	subsys_interface_unregister(&cpufreq_interface);
>  	remove_boost_sysfs_file();
> -	cpuhp_remove_state_nocalls(hp_online);
> +	cpuhp_remove_state_nocalls_locked(hp_online);
>  
>  	write_lock_irqsave(&cpufreq_driver_lock, flags);

Acked-by: Viresh Kumar <viresh.kumar@linaro.org>

-- 
viresh