linux-kernel - Re: [PATCH 2/2] cpufreq: Use static SRCU initializer

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Date:   Wed, 30 May 2018 10:20:34 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 2/2] cpufreq: Use static SRCU initializer

On 25-05-18, 12:19, Sebastian Andrzej Siewior wrote:
> Use the static SRCU initializer for `cpufreq_transition_notifier_list'.
> This avoids the init_cpufreq_transition_notifier_list() initcall. Its
> only purpose is to initialize the SRCU notifier once during boot and set
> another variable which is used as an indicator whether the init was
> perfromed before cpufreq_register_notifier() was used.
> 
> Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>
> CC: Viresh Kumar <viresh.kumar@...aro.org>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
> ---
>  drivers/cpufreq/cpufreq.c | 13 +------------
>  1 file changed, 1 insertion(+), 12 deletions(-)
> 
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 075d18f6ba7a..3f7b502cfb1e 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -89,16 +89,7 @@ static void cpufreq_governor_limits(struct cpufreq_policy *policy);
>   * The mutex locks both lists.
>   */
>  static BLOCKING_NOTIFIER_HEAD(cpufreq_policy_notifier_list);
> -static struct srcu_notifier_head cpufreq_transition_notifier_list;
> -
> -static bool init_cpufreq_transition_notifier_list_called;
> -static int __init init_cpufreq_transition_notifier_list(void)
> -{
> -	srcu_init_notifier_head(&cpufreq_transition_notifier_list);
> -	init_cpufreq_transition_notifier_list_called = true;
> -	return 0;
> -}
> -pure_initcall(init_cpufreq_transition_notifier_list);
> +SRCU_NOTIFIER_HEAD_STATIC(cpufreq_transition_notifier_list);
>  
>  static int off __read_mostly;
>  static int cpufreq_disabled(void)
> @@ -1764,8 +1755,6 @@ int cpufreq_register_notifier(struct notifier_block *nb, unsigned int list)
>  	if (cpufreq_disabled())
>  		return -EINVAL;
>  
> -	WARN_ON(!init_cpufreq_transition_notifier_list_called);
> -
>  	switch (list) {
>  	case CPUFREQ_TRANSITION_NOTIFIER:
>  		mutex_lock(&cpufreq_fast_switch_lock);

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

-- 
viresh