Re: [PATCH 12/21] cpufreq: Convert to hotplug state machine

Rafael J. Wysocki
2016-09-06T21:27:53Z

On Tue, Sep 6, 2016 at 7:04 PM, Sebastian Andrzej Siewior
<bigeasy@linutronix.de> wrote:
> Install the callbacks via the state machine.
>
> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
> Cc: Viresh Kumar <viresh.kumar@linaro.org>
> Cc: linux-pm@vger.kernel.org
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> ---
> drivers/cpufreq/cpufreq.c | 38 ++++++++++++--------------------------
> 1 file changed, 12 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 3dd4884c6f9e..e0bc632a259e 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -1358,7 +1358,7 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
> return add_cpu_dev_symlink(policy, cpu);
> }
>
> -static void cpufreq_offline(unsigned int cpu)
> +static int cpufreq_offline(unsigned int cpu)
> {
> struct cpufreq_policy *policy;
> int ret;
> @@ -1368,7 +1368,7 @@ static void cpufreq_offline(unsigned int cpu)
> policy = cpufreq_cpu_get_raw(cpu);
> if (!policy) {
> pr_debug("%s: No cpu_data found\n", __func__);
> - return;
> + return 0;
> }
>
> down_write(&policy->rwsem);
> @@ -1417,6 +1417,7 @@ static void cpufreq_offline(unsigned int cpu)
>
> unlock:
> up_write(&policy->rwsem);
> + return 0;
> }
>
> /**
> @@ -2332,28 +2333,6 @@ int cpufreq_update_policy(unsigned int cpu)
> }
> EXPORT_SYMBOL(cpufreq_update_policy);
>
> -static int cpufreq_cpu_callback(struct notifier_block *nfb,
> - unsigned long action, void *hcpu)
> -{
> - unsigned int cpu = (unsigned long)hcpu;
> -
> - switch (action & ~CPU_TASKS_FROZEN) {
> - case CPU_ONLINE:
> - case CPU_DOWN_FAILED:
> - cpufreq_online(cpu);
> - break;
> -
> - case CPU_DOWN_PREPARE:
> - cpufreq_offline(cpu);
> - break;
> - }
> - return NOTIFY_OK;
> -}
> -
> -static struct notifier_block __refdata cpufreq_cpu_notifier = {
> - .notifier_call = cpufreq_cpu_callback,
> -};
> -
> /*********************************************************************
> * BOOST *
> *********************************************************************/
> @@ -2455,6 +2434,7 @@ EXPORT_SYMBOL_GPL(cpufreq_boost_enabled);
> /*********************************************************************
> * REGISTER / UNREGISTER CPUFREQ DRIVER *
> *********************************************************************/
> +static enum cpuhp_state hp_online;
>
> /**
> * cpufreq_register_driver - register a CPU Frequency driver
> @@ -2517,7 +2497,13 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
> goto err_if_unreg;
> }
>
> - register_hotcpu_notifier(&cpufreq_cpu_notifier);
> + ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "cpufreq:online",
> + cpufreq_online,
> + cpufreq_offline);
> + if (ret < 0)
> + goto err_if_unreg;
> + hp_online = ret;

hp_online is enum cpuhp_state (and we pass it to
cpuhp_remove_state_nocalls(() later on), but
cpuhp_setup_state_nocalls() returns an int (and that should be 0 if it
is not an error code AFAICS), so is this actually correct?

Thanks,
Rafael