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    Subject[tip:smp/hotplug] cpuidle/coupled: Convert to hotplug state machine
    Commit-ID:  a4bf5aaae070d07a98a78a56e5db79779a949b9d
    Gitweb: http://git.kernel.org/tip/a4bf5aaae070d07a98a78a56e5db79779a949b9d
    Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
    AuthorDate: Wed, 24 Aug 2016 11:14:44 +0200
    Committer: Thomas Gleixner <tglx@linutronix.de>
    CommitDate: Tue, 6 Sep 2016 16:20:31 +0200

    cpuidle/coupled: Convert to hotplug state machine

    Install the callbacks via the state machine.

    Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
    Cc: linux-pm@vger.kernel.org
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
    Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
    Cc: rt@linutronix.de
    Link: http://lkml.kernel.org/r/20160824091444.brdr5zpbxjvh6n3f@linutronix.de
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

    ---
    drivers/cpuidle/coupled.c | 75 +++++++++++++++++++---------------------------
    include/linux/cpuhotplug.h | 1 +
    2 files changed, 32 insertions(+), 44 deletions(-)

    diff --git a/drivers/cpuidle/coupled.c b/drivers/cpuidle/coupled.c
    index d5657d5..71e586d 100644
    --- a/drivers/cpuidle/coupled.c
    +++ b/drivers/cpuidle/coupled.c
    @@ -749,65 +749,52 @@ static void cpuidle_coupled_allow_idle(struct cpuidle_coupled *coupled)
    put_cpu();
    }

    -/**
    - * cpuidle_coupled_cpu_notify - notifier called during hotplug transitions
    - * @nb: notifier block
    - * @action: hotplug transition
    - * @hcpu: target cpu number
    - *
    - * Called when a cpu is brought on or offline using hotplug. Updates the
    - * coupled cpu set appropriately
    - */
    -static int cpuidle_coupled_cpu_notify(struct notifier_block *nb,
    - unsigned long action, void *hcpu)
    +static int coupled_cpu_online(unsigned int cpu)
    {
    - int cpu = (unsigned long)hcpu;
    struct cpuidle_device *dev;

    - switch (action & ~CPU_TASKS_FROZEN) {
    - case CPU_UP_PREPARE:
    - case CPU_DOWN_PREPARE:
    - case CPU_ONLINE:
    - case CPU_DEAD:
    - case CPU_UP_CANCELED:
    - case CPU_DOWN_FAILED:
    - break;
    - default:
    - return NOTIFY_OK;
    - }
    -
    mutex_lock(&cpuidle_lock);

    dev = per_cpu(cpuidle_devices, cpu);
    - if (!dev || !dev->coupled)
    - goto out;
    -
    - switch (action & ~CPU_TASKS_FROZEN) {
    - case CPU_UP_PREPARE:
    - case CPU_DOWN_PREPARE:
    - cpuidle_coupled_prevent_idle(dev->coupled);
    - break;
    - case CPU_ONLINE:
    - case CPU_DEAD:
    + if (dev && dev->coupled) {
    cpuidle_coupled_update_online_cpus(dev->coupled);
    - /* Fall through */
    - case CPU_UP_CANCELED:
    - case CPU_DOWN_FAILED:
    cpuidle_coupled_allow_idle(dev->coupled);
    - break;
    }

    -out:
    mutex_unlock(&cpuidle_lock);
    - return NOTIFY_OK;
    + return 0;
    }

    -static struct notifier_block cpuidle_coupled_cpu_notifier = {
    - .notifier_call = cpuidle_coupled_cpu_notify,
    -};
    +static int coupled_cpu_up_prepare(unsigned int cpu)
    +{
    + struct cpuidle_device *dev;
    +
    + mutex_lock(&cpuidle_lock);
    +
    + dev = per_cpu(cpuidle_devices, cpu);
    + if (dev && dev->coupled)
    + cpuidle_coupled_prevent_idle(dev->coupled);
    +
    + mutex_unlock(&cpuidle_lock);
    + return 0;
    +}

    static int __init cpuidle_coupled_init(void)
    {
    - return register_cpu_notifier(&cpuidle_coupled_cpu_notifier);
    + int ret;
    +
    + ret = cpuhp_setup_state_nocalls(CPUHP_CPUIDLE_COUPLED_PREPARE,
    + "cpuidle/coupled:prepare",
    + coupled_cpu_up_prepare,
    + coupled_cpu_online);
    + if (ret)
    + return ret;
    + ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
    + "cpuidle/coupled:online",
    + coupled_cpu_online,
    + coupled_cpu_up_prepare);
    + if (ret < 0)
    + cpuhp_remove_state_nocalls(CPUHP_CPUIDLE_COUPLED_PREPARE);
    + return ret;
    }
    core_initcall(cpuidle_coupled_init);
    diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
    index 962c37b..adbda13 100644
    --- a/include/linux/cpuhotplug.h
    +++ b/include/linux/cpuhotplug.h
    @@ -29,6 +29,7 @@ enum cpuhp_state {
    CPUHP_RELAY_PREPARE,
    CPUHP_RCUTREE_PREP,
    CPUHP_MD_RAID5_PREPARE,
    + CPUHP_CPUIDLE_COUPLED_PREPARE,
    CPUHP_NOTIFY_PREPARE,
    CPUHP_TIMERS_DEAD,
    CPUHP_BRINGUP_CPU,
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