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Groups > linux.kernel > #1346595

Re: [RFCv7 PATCH 03/10] sched: scheduler-driven cpu frequency selection

From Peter Zijlstra <peterz@infradead.org>
Newsgroups linux.kernel
Subject Re: [RFCv7 PATCH 03/10] sched: scheduler-driven cpu frequency selection
Date 2016-03-01 14:00 +0100
Message-ID <r7S4b-Pg-43@gated-at.bofh.it> (permalink)
References <r59Xz-6rQ-1@gated-at.bofh.it> <r6bkC-1f7-7@gated-at.bofh.it> <r6mJ4-Wa-1@gated-at.bofh.it> <r6ACl-2Pe-3@gated-at.bofh.it>
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On Sat, Feb 27, 2016 at 01:08:02AM +0100, Rafael J. Wysocki wrote:
> @@ -95,18 +98,20 @@ EXPORT_SYMBOL_GPL(cpufreq_set_update_uti
>   *
>   * This function is called by the scheduler on every invocation of
>   * update_load_avg() on the CPU whose utilization is being updated.
> + *
> + * It can only be called from RCU-sched read-side critical sections.
>   */
>  void cpufreq_update_util(u64 time, unsigned long util, unsigned long max)
>  {
>  	struct update_util_data *data;
>  
> -	rcu_read_lock();
> -

Maybe, just because I'm paranoid, add something like:

#ifdef CONFIG_LOCKDEP
	WARN_ON(debug_locks && !rcu_read_lock_sched_held());
#endif

>  	data = rcu_dereference(*this_cpu_ptr(&cpufreq_update_util_data));
> -	if (data && data->func)
> +	/*
> +	 * If this isn't inside of an RCU-sched read-side critical section, data
> +	 * may become NULL after the check below.
> +	 */
> +	if (data)
>  		data->func(data, time, util, max);
> -
> -	rcu_read_unlock();
>  }

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Thread

[RFCv7 PATCH 00/10] sched: scheduler-driven CPU frequency selection Steve Muckle <steve.muckle@linaro.org> - 2016-02-23 02:30 +0100
  [RFCv7 PATCH 07/10] sched/fair: jump to max OPP when crossing UP threshold Steve Muckle <steve.muckle@linaro.org> - 2016-02-23 02:30 +0100
  [RFCv7 PATCH 09/10] sched/deadline: split rt_avg in 2 distincts metrics Steve Muckle <steve.muckle@linaro.org> - 2016-02-23 02:30 +0100
  [RFCv7 PATCH 10/10] sched: rt scheduler sets capacity requirement Steve Muckle <steve.muckle@linaro.org> - 2016-02-23 02:30 +0100
  [RFCv7 PATCH 08/10] sched: remove call of sched_avg_update from sched_rt_avg_update Steve Muckle <steve.muckle@linaro.org> - 2016-02-23 02:30 +0100
  [RFCv7 PATCH 02/10] cpufreq: introduce cpufreq_driver_is_slow Steve Muckle <steve.muckle@linaro.org> - 2016-02-23 02:30 +0100
    Re: [RFCv7 PATCH 02/10] cpufreq: introduce cpufreq_driver_is_slow "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-23 02:40 +0100
      Re: [RFCv7 PATCH 02/10] cpufreq: introduce cpufreq_driver_is_slow Michael Turquette <mturquette@baylibre.com> - 2016-02-26 02:10 +0100
        Re: [RFCv7 PATCH 02/10] cpufreq: introduce cpufreq_driver_is_slow "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-26 02:20 +0100
          Re: [RFCv7 PATCH 02/10] cpufreq: introduce cpufreq_driver_is_slow "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-26 22:10 +0100
        Re: [RFCv7 PATCH 02/10] cpufreq: introduce cpufreq_driver_is_slow Steve Muckle <steve.muckle@linaro.org> - 2016-02-26 02:20 +0100
  [RFCv7 PATCH 06/10] sched/fair: cpufreq_sched triggers for load balancing Steve Muckle <steve.muckle@linaro.org> - 2016-02-23 02:30 +0100
  [RFCv7 PATCH 04/10] sched/fair: add triggers for OPP change requests Steve Muckle <steve.muckle@linaro.org> - 2016-02-23 02:30 +0100
    Re: [RFCv7 PATCH 04/10] sched/fair: add triggers for OPP change requests Ricky Liang <jcliang@chromium.org> - 2016-03-01 08:00 +0100
      Re: [RFCv7 PATCH 04/10] sched/fair: add triggers for OPP change  requests Steve Muckle <steve.muckle@linaro.org> - 2016-03-03 05:00 +0100
  [RFCv7 PATCH 03/10] sched: scheduler-driven cpu frequency selection Steve Muckle <steve.muckle@linaro.org> - 2016-02-23 02:30 +0100
    Re: [RFCv7 PATCH 03/10] sched: scheduler-driven cpu frequency selection "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-25 05:00 +0100
      Re: [RFCv7 PATCH 03/10] sched: scheduler-driven cpu frequency  selection Peter Zijlstra <peterz@infradead.org> - 2016-02-25 10:30 +0100
        Re: [RFCv7 PATCH 03/10] sched: scheduler-driven cpu frequency selection "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-25 22:10 +0100
      Re: [RFCv7 PATCH 03/10] sched: scheduler-driven cpu frequency  selection Peter Zijlstra <peterz@infradead.org> - 2016-02-25 10:30 +0100
        Re: [RFCv7 PATCH 03/10] sched: scheduler-driven cpu frequency selection "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-25 22:10 +0100
          Re: [RFCv7 PATCH 03/10] sched: scheduler-driven cpu frequency  selection Peter Zijlstra <peterz@infradead.org> - 2016-02-26 10:20 +0100
            Re: [RFCv7 PATCH 03/10] sched: scheduler-driven cpu frequency selection "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-27 01:10 +0100
              Re: [RFCv7 PATCH 03/10] sched: scheduler-driven cpu frequency  selection Peter Zijlstra <peterz@infradead.org> - 2016-03-01 14:00 +0100
                Re: [RFCv7 PATCH 03/10] sched: scheduler-driven cpu frequency selection "Rafael J. Wysocki" <rafael@kernel.org> - 2016-03-01 20:50 +0100
      Re: [RFCv7 PATCH 03/10] sched: scheduler-driven cpu frequency selection "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-25 12:10 +0100
      Re: [RFCv7 PATCH 03/10] sched: scheduler-driven cpu frequency  selection Steve Muckle <steve.muckle@linaro.org> - 2016-02-26 01:40 +0100
        Re: [RFCv7 PATCH 03/10] sched: scheduler-driven cpu frequency selection "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-27 03:40 +0100
          Re: [RFCv7 PATCH 03/10] sched: scheduler-driven cpu frequency  selection Steve Muckle <steve.muckle@linaro.org> - 2016-02-27 05:20 +0100
            Re: [RFCv7 PATCH 03/10] sched: scheduler-driven cpu frequency selection "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-28 03:30 +0100
              Re: [RFCv7 PATCH 03/10] sched: scheduler-driven cpu frequency  selection Peter Zijlstra <peterz@infradead.org> - 2016-03-01 15:40 +0100
                Re: [RFCv7 PATCH 03/10] sched: scheduler-driven cpu frequency selection "Rafael J. Wysocki" <rafael@kernel.org> - 2016-03-01 21:40 +0100
            Re: [RFCv7 PATCH 03/10] sched: scheduler-driven cpu frequency  selection Peter Zijlstra <peterz@infradead.org> - 2016-03-01 14:30 +0100
        Re: [RFCv7 PATCH 03/10] sched: scheduler-driven cpu frequency  selection Peter Zijlstra <peterz@infradead.org> - 2016-03-01 14:20 +0100
        Re: [RFCv7 PATCH 03/10] sched: scheduler-driven cpu frequency selection Michael Turquette <mturquette@baylibre.com> - 2016-03-02 08:50 +0100
          Re: [RFCv7 PATCH 03/10] sched: scheduler-driven cpu frequency selection "Rafael J. Wysocki" <rafael@kernel.org> - 2016-03-03 03:50 +0100
            Re: [RFCv7 PATCH 03/10] sched: scheduler-driven cpu frequency  selection Steve Muckle <steve.muckle@linaro.org> - 2016-03-03 05:00 +0100
              Re: [RFCv7 PATCH 03/10] sched: scheduler-driven cpu frequency  selection Juri Lelli <Juri.Lelli@arm.com> - 2016-03-03 10:40 +0100
          Re: [RFCv7 PATCH 03/10] sched: scheduler-driven cpu frequency  selection Peter Zijlstra <peterz@infradead.org> - 2016-03-03 14:10 +0100
    Re: [RFCv7 PATCH 03/10] sched: scheduler-driven cpu frequency  selection Ingo Molnar <mingo@kernel.org> - 2016-03-03 15:30 +0100
  [RFCv7 PATCH 05/10] sched/{core,fair}: trigger OPP change request on fork() Steve Muckle <steve.muckle@linaro.org> - 2016-02-23 02:30 +0100
  [RFCv7 PATCH 01/10] sched: Compute cpu capacity available at current frequency Steve Muckle <steve.muckle@linaro.org> - 2016-02-23 02:30 +0100
    Re: [RFCv7 PATCH 01/10] sched: Compute cpu capacity available at  current frequency "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-23 02:50 +0100
      Re: [RFCv7 PATCH 01/10] sched: Compute cpu capacity available at  current frequency Peter Zijlstra <peterz@infradead.org> - 2016-02-23 10:20 +0100
        Re: [RFCv7 PATCH 01/10] sched: Compute cpu capacity available at current frequency "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-26 02:40 +0100
          Re: [RFCv7 PATCH 01/10] sched: Compute cpu capacity available at  current frequency Peter Zijlstra <peterz@infradead.org> - 2016-02-26 10:20 +0100
  Re: [RFCv7 PATCH 00/10] sched: scheduler-driven CPU frequency  selection Steve Muckle <steve.muckle@linaro.org> - 2016-02-23 02:40 +0100

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