Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1404071

Re: [PATCH v2] cpufreq: stats: Walk online CPUs with CPU offline/online locked

From Viresh Kumar <viresh.kumar@linaro.org>
Newsgroups linux.kernel
Subject Re: [PATCH v2] cpufreq: stats: Walk online CPUs with CPU offline/online locked
Date 2016-05-20 04:30 +0200
Message-ID <rAIml-86S-1@gated-at.bofh.it> (permalink)
References <rAHzX-7w9-1@gated-at.bofh.it> <rAHzX-7w9-11@gated-at.bofh.it>
Organization linux.* mail to news gateway

Show all headers | View raw

On 20-05-16, 03:41, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> Loops over online CPUs in cpufreq_stats_init() and cpufreq_stats_exit()
> should be carried out with CPU offline/online locked or races are
> possible otherwise, so make that happen.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
> 
> v1 -> v2: On a second thought, add the policy notifier in cpufreq_stats_init()
>   with CPU offline/online locked too.
> 
> ---
>  drivers/cpufreq/cpufreq_stats.c |   16 +++++++++++++---
>  1 file changed, 13 insertions(+), 3 deletions(-)
> 
> Index: linux-pm/drivers/cpufreq/cpufreq_stats.c
> ===================================================================
> --- linux-pm.orig/drivers/cpufreq/cpufreq_stats.c
> +++ linux-pm/drivers/cpufreq/cpufreq_stats.c
> @@ -317,10 +317,13 @@ static int __init cpufreq_stats_init(voi
>  	unsigned int cpu;
>  
>  	spin_lock_init(&cpufreq_stats_lock);
> +
> +	get_online_cpus();
> +
>  	ret = cpufreq_register_notifier(&notifier_policy_block,
>  				CPUFREQ_POLICY_NOTIFIER);

Why is this required to be protected ?

>  	if (ret)
> -		return ret;
> +		goto out;
>  
>  	for_each_online_cpu(cpu)
>  		cpufreq_stats_create_table(cpu);
> @@ -332,21 +335,28 @@ static int __init cpufreq_stats_init(voi
>  				CPUFREQ_POLICY_NOTIFIER);
>  		for_each_online_cpu(cpu)
>  			cpufreq_stats_free_table(cpu);

Maybe we can make this for_each_possible_cpu() then, and so getting a
policy will fail for CPUs which aren't online.

And we wouldn't need to use get_online_cpus() then ?

-- 
viresh

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH] cpufreq: stats: Walk online CPUs with CPU offline/online locked "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-05-20 03:40 +0200
  [PATCH v2] cpufreq: stats: Walk online CPUs with CPU offline/online locked "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-05-20 03:40 +0200
    Re: [PATCH v2] cpufreq: stats: Walk online CPUs with CPU  offline/online locked Viresh Kumar <viresh.kumar@linaro.org> - 2016-05-20 04:30 +0200
      Re: [PATCH v2] cpufreq: stats: Walk online CPUs with CPU offline/online locked "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-05-20 14:20 +0200
        Re: [PATCH v2] cpufreq: stats: Walk online CPUs with CPU offline/online locked "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-05-20 23:30 +0200
          Re: [PATCH v2] cpufreq: stats: Walk online CPUs with CPU  offline/online locked Viresh Kumar <viresh.kumar@linaro.org> - 2016-05-23 06:00 +0200
            Re: [PATCH v2] cpufreq: stats: Walk online CPUs with CPU offline/online locked "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-05-23 15:40 +0200
              Re: [PATCH v2] cpufreq: stats: Walk online CPUs with CPU  offline/online locked Viresh Kumar <viresh.kumar@linaro.org> - 2016-05-23 17:20 +0200
                Re: [PATCH v2] cpufreq: stats: Walk online CPUs with CPU  offline/online locked "Rafael J. Wysocki" <rafael@kernel.org> - 2016-05-23 22:50 +0200
                Re: [PATCH v2] cpufreq: stats: Walk online CPUs with CPU  offline/online locked Viresh Kumar <viresh.kumar@linaro.org> - 2016-05-24 07:00 +0200
                Re: [PATCH v2] cpufreq: stats: Walk online CPUs with CPU offline/online locked "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-05-24 14:20 +0200
                Re: [PATCH v2] cpufreq: stats: Walk online CPUs with CPU  offline/online locked Viresh Kumar <viresh.kumar@linaro.org> - 2016-05-24 14:20 +0200
                Re: [PATCH v2] cpufreq: stats: Walk online CPUs with CPU offline/online locked "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-05-25 02:00 +0200
                Re: [PATCH v2] cpufreq: stats: Walk online CPUs with CPU  offline/online locked "Rafael J. Wysocki" <rafael@kernel.org> - 2016-05-25 02:50 +0200
                Re: [PATCH v2] cpufreq: stats: Walk online CPUs with CPU  offline/online locked Viresh Kumar <viresh.kumar@linaro.org> - 2016-05-25 04:10 +0200

csiph-web