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

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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

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[patch 00/20] cpu/hotplug: Convert get_online_cpus() to a percpu_rwsem Thomas Gleixner <tglx@linutronix.de> - 2017-04-15 19:40 +0200
  [patch 02/20] stop_machine: Provide stop_machine_locked() Thomas Gleixner <tglx@linutronix.de> - 2017-04-15 19:40 +0200
  [patch 20/20] cpu/hotplug: Convert hotplug locking to percpu rwsem Thomas Gleixner <tglx@linutronix.de> - 2017-04-15 19:40 +0200
    Re: [patch 20/20] cpu/hotplug: Convert hotplug locking to percpu  rwsem Peter Zijlstra <peterz@infradead.org> - 2017-04-17 09:00 +0200
  [patch 17/20] PCI: Use cpu_hotplug_disable() instead of  get_online_cpus() Thomas Gleixner <tglx@linutronix.de> - 2017-04-15 19:40 +0200
    Re: [patch 17/20] PCI: Use cpu_hotplug_disable() instead of  get_online_cpus() Peter Zijlstra <peterz@infradead.org> - 2017-04-17 08:50 +0200
      Re: [patch 17/20] PCI: Use cpu_hotplug_disable() instead of  get_online_cpus() Thomas Gleixner <tglx@linutronix.de> - 2017-04-17 09:50 +0200
    Re: [patch 17/20] PCI: Use cpu_hotplug_disable() instead of  get_online_cpus() Bjorn Helgaas <helgaas@kernel.org> - 2017-04-18 21:50 +0200
      Re: [patch 17/20] PCI: Use cpu_hotplug_disable() instead of  get_online_cpus() Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 22:00 +0200
  [patch 12/20] s390/kernel: Use stop_machine_locked() Thomas Gleixner <tglx@linutronix.de> - 2017-04-15 19:40 +0200
  [patch 13/20] powerpc/powernv: Use stop_machine_locked() Thomas Gleixner <tglx@linutronix.de> - 2017-04-15 19:40 +0200
  [patch 03/20] padata: Make padata_alloc() static Thomas Gleixner <tglx@linutronix.de> - 2017-04-15 19:40 +0200
    Re: [patch 03/20] padata: Make padata_alloc() static "Jason A. Donenfeld" <Jason@zx2c4.com> - 2017-04-16 08:30 +0200
      Re: [patch 03/20] padata: Make padata_alloc() static Thomas Gleixner <tglx@linutronix.de> - 2017-04-17 11:20 +0200
  [patch 01/20] cpu/hotplug: Provide  cpuhp_setup/remove_state[_nocalls]_locked() Thomas Gleixner <tglx@linutronix.de> - 2017-04-15 19:40 +0200
  [patch 18/20] PCI: Replace the racy recursion prevention Thomas Gleixner <tglx@linutronix.de> - 2017-04-15 19:40 +0200
  [patch 04/20] padata: Avoid nested calls to get_online_cpus() in  pcrypt_init_padata() Thomas Gleixner <tglx@linutronix.de> - 2017-04-15 19:40 +0200
  [patch 14/20] kernel/hotplug: Use stop_machine_locked() in  takedown_cpu() Thomas Gleixner <tglx@linutronix.de> - 2017-04-15 19:40 +0200
  [patch 05/20] x86/mtrr: Remove get_online_cpus() from  mtrr_save_state() Thomas Gleixner <tglx@linutronix.de> - 2017-04-15 19:40 +0200
  [patch 07/20] KVM/PPC/Book3S HV: Use  cpuhp_setup_state_nocalls_locked() Thomas Gleixner <tglx@linutronix.de> - 2017-04-15 19:40 +0200
  [patch 16/20] perf/x86/intel: Drop get_online_cpus() in  intel_snb_check_microcode() Thomas Gleixner <tglx@linutronix.de> - 2017-04-15 19:40 +0200
    Re: [patch 16/20] perf/x86/intel: Drop get_online_cpus() in  intel_snb_check_microcode() Borislav Petkov <bp@alien8.de> - 2017-04-18 13:30 +0200
  [patch 09/20] hwtracing/coresight-etm4x: Use  cpuhp_setup_state_nocalls_locked() Thomas Gleixner <tglx@linutronix.de> - 2017-04-15 19:40 +0200
  [patch 10/20] perf/x86/intel/cqm: Use cpuhp_setup_state_locked() Thomas Gleixner <tglx@linutronix.de> - 2017-04-15 19:40 +0200
  [patch 06/20] cpufreq: Use cpuhp_setup_state_nocalls_locked() Thomas Gleixner <tglx@linutronix.de> - 2017-04-15 19:40 +0200
    Re: [patch 06/20] cpufreq: Use cpuhp_setup_state_nocalls_locked() "Rafael J. Wysocki" <rafael@kernel.org> - 2017-04-16 01:00 +0200
    Re: [patch 06/20] cpufreq: Use cpuhp_setup_state_nocalls_locked() Viresh Kumar <viresh.kumar@linaro.org> - 2017-04-17 06:20 +0200
  [patch 08/20] hwtracing/coresight-etm3x: Use the locked version of  cpuhp_setup_state_nocalls() Thomas Gleixner <tglx@linutronix.de> - 2017-04-15 19:40 +0200
  [patch 11/20] ARM/hw_breakpoint: Use cpuhp_setup_state_locked() Thomas Gleixner <tglx@linutronix.de> - 2017-04-15 19:40 +0200

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