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    Subject[tip:smp/hotplug] x86/hpet: Convert to hotplug state machine
    Commit-ID:  48d7f6c715782a6f6d4a5535f1233b764ce6b6f2
    Gitweb: http://git.kernel.org/tip/48d7f6c715782a6f6d4a5535f1233b764ce6b6f2
    Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
    AuthorDate: Wed, 13 Jul 2016 17:16:30 +0000
    Committer: Ingo Molnar <mingo@kernel.org>
    CommitDate: Thu, 14 Jul 2016 09:34:44 +0200

    x86/hpet: Convert to hotplug state machine

    Install the callbacks via the state machine and let the core invoke
    the callbacks on the already online CPUs.

    Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
    Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
    Cc: Andy Lutomirski <luto@kernel.org>
    Cc: Borislav Petkov <bp@suse.de>
    Cc: Denys Vlasenko <dvlasenk@redhat.com>
    Cc: Jan Beulich <JBeulich@suse.com>
    Cc: Jiang Liu <jiang.liu@linux.intel.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Viresh Kumar <viresh.kumar@linaro.org>
    Cc: rt@linutronix.de
    Link: http://lkml.kernel.org/r/20160713153335.279718463@linutronix.de
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    ---
    arch/x86/kernel/hpet.c | 69 +++++++++++++++++++++++-----------------------
    include/linux/cpuhotplug.h | 2 ++
    2 files changed, 36 insertions(+), 35 deletions(-)

    diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
    index f112af7..3d74707 100644
    --- a/arch/x86/kernel/hpet.c
    +++ b/arch/x86/kernel/hpet.c
    @@ -710,31 +710,29 @@ static void hpet_work(struct work_struct *w)
    complete(&hpet_work->complete);
    }

    -static int hpet_cpuhp_notify(struct notifier_block *n,
    - unsigned long action, void *hcpu)
    +static int hpet_cpuhp_online(unsigned int cpu)
    {
    - unsigned long cpu = (unsigned long)hcpu;
    struct hpet_work_struct work;
    +
    + INIT_DELAYED_WORK_ONSTACK(&work.work, hpet_work);
    + init_completion(&work.complete);
    + /* FIXME: add schedule_work_on() */
    + schedule_delayed_work_on(cpu, &work.work, 0);
    + wait_for_completion(&work.complete);
    + destroy_delayed_work_on_stack(&work.work);
    + return 0;
    +}
    +
    +static int hpet_cpuhp_dead(unsigned int cpu)
    +{
    struct hpet_dev *hdev = per_cpu(cpu_hpet_dev, cpu);

    - switch (action & ~CPU_TASKS_FROZEN) {
    - case CPU_ONLINE:
    - INIT_DELAYED_WORK_ONSTACK(&work.work, hpet_work);
    - init_completion(&work.complete);
    - /* FIXME: add schedule_work_on() */
    - schedule_delayed_work_on(cpu, &work.work, 0);
    - wait_for_completion(&work.complete);
    - destroy_delayed_work_on_stack(&work.work);
    - break;
    - case CPU_DEAD:
    - if (hdev) {
    - free_irq(hdev->irq, hdev);
    - hdev->flags &= ~HPET_DEV_USED;
    - per_cpu(cpu_hpet_dev, cpu) = NULL;
    - }
    - break;
    - }
    - return NOTIFY_OK;
    + if (!hdev)
    + return 0;
    + free_irq(hdev->irq, hdev);
    + hdev->flags &= ~HPET_DEV_USED;
    + per_cpu(cpu_hpet_dev, cpu) = NULL;
    + return 0;
    }
    #else

    @@ -750,11 +748,8 @@ static void hpet_reserve_msi_timers(struct hpet_data *hd)
    }
    #endif

    -static int hpet_cpuhp_notify(struct notifier_block *n,
    - unsigned long action, void *hcpu)
    -{
    - return NOTIFY_OK;
    -}
    +#define hpet_cpuhp_online NULL
    +#define hpet_cpuhp_dead NULL

    #endif

    @@ -931,7 +926,7 @@ out_nohpet:
    */
    static __init int hpet_late_init(void)
    {
    - int cpu;
    + int ret;

    if (boot_hpet_disable)
    return -ENODEV;
    @@ -961,16 +956,20 @@ static __init int hpet_late_init(void)
    if (boot_cpu_has(X86_FEATURE_ARAT))
    return 0;

    - cpu_notifier_register_begin();
    - for_each_online_cpu(cpu) {
    - hpet_cpuhp_notify(NULL, CPU_ONLINE, (void *)(long)cpu);
    - }
    -
    /* This notifier should be called after workqueue is ready */
    - __hotcpu_notifier(hpet_cpuhp_notify, -20);
    - cpu_notifier_register_done();
    -
    + ret = cpuhp_setup_state(CPUHP_AP_X86_HPET_ONLINE, "AP_X86_HPET_ONLINE",
    + hpet_cpuhp_online, NULL);
    + if (ret)
    + return ret;
    + ret = cpuhp_setup_state(CPUHP_X86_HPET_DEAD, "X86_HPET_DEAD", NULL,
    + hpet_cpuhp_dead);
    + if (ret)
    + goto err_cpuhp;
    return 0;
    +
    +err_cpuhp:
    + cpuhp_remove_state(CPUHP_AP_X86_HPET_ONLINE);
    + return ret;
    }
    fs_initcall(hpet_late_init);

    diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
    index 60557a9..7449081 100644
    --- a/include/linux/cpuhotplug.h
    +++ b/include/linux/cpuhotplug.h
    @@ -12,6 +12,7 @@ enum cpuhp_state {
    CPUHP_PERF_BFIN,
    CPUHP_PERF_POWER,
    CPUHP_PERF_SUPERH,
    + CPUHP_X86_HPET_DEAD,
    CPUHP_WORKQUEUE_PREP,
    CPUHP_NOTIFY_PREPARE,
    CPUHP_BRINGUP_CPU,
    @@ -54,6 +55,7 @@ enum cpuhp_state {
    CPUHP_AP_NOTIFY_ONLINE,
    CPUHP_AP_ONLINE_DYN,
    CPUHP_AP_ONLINE_DYN_END = CPUHP_AP_ONLINE_DYN + 30,
    + CPUHP_AP_X86_HPET_ONLINE,
    CPUHP_AP_ACTIVE,
    CPUHP_ONLINE,
    };
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