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    Subject[tip: smp/core] cpu/hotplug: Hide cpu_up/down()
    The following commit has been merged into the smp/core branch of tip:

    Commit-ID: 33c3736ec88811b9b6f6ce2cc8967f6b97c3db5e
    Gitweb: https://git.kernel.org/tip/33c3736ec88811b9b6f6ce2cc8967f6b97c3db5e
    Author: Qais Yousef <qais.yousef@arm.com>
    AuthorDate: Mon, 23 Mar 2020 13:51:10
    Committer: Thomas Gleixner <tglx@linutronix.de>
    CommitterDate: Wed, 25 Mar 2020 12:59:38 +01:00

    cpu/hotplug: Hide cpu_up/down()

    Use separate functions for the device core to bring a CPU up and down.

    Users outside the device core must use add/remove_cpu() which will take
    care of extra housekeeping work like keeping sysfs in sync.

    Make cpu_up/down() static and replace the extra layer of indirection.

    [ tglx: Removed the extra wrapper functions and adjusted function names ]

    Signed-off-by: Qais Yousef <qais.yousef@arm.com>
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Link: https://lkml.kernel.org/r/20200323135110.30522-18-qais.yousef@arm.com
    ---
    drivers/base/cpu.c | 4 ++--
    include/linux/cpu.h | 4 ++--
    kernel/cpu.c | 42 ++++++++++++++++++++++++++++--------------
    3 files changed, 32 insertions(+), 18 deletions(-)

    diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
    index 6265871..b93a8f8 100644
    --- a/drivers/base/cpu.c
    +++ b/drivers/base/cpu.c
    @@ -55,7 +55,7 @@ static int cpu_subsys_online(struct device *dev)
    if (from_nid == NUMA_NO_NODE)
    return -ENODEV;

    - ret = cpu_up(cpuid);
    + ret = cpu_device_up(dev);
    /*
    * When hot adding memory to memoryless node and enabling a cpu
    * on the node, node number of the cpu may internally change.
    @@ -69,7 +69,7 @@ static int cpu_subsys_online(struct device *dev)

    static int cpu_subsys_offline(struct device *dev)
    {
    - return cpu_down(dev->id);
    + return cpu_device_down(dev);
    }

    void unregister_cpu(struct cpu *cpu)
    diff --git a/include/linux/cpu.h b/include/linux/cpu.h
    index 8b295f7..9ead281 100644
    --- a/include/linux/cpu.h
    +++ b/include/linux/cpu.h
    @@ -88,8 +88,8 @@ extern ssize_t arch_cpu_release(const char *, size_t);

    #ifdef CONFIG_SMP
    extern bool cpuhp_tasks_frozen;
    -int cpu_up(unsigned int cpu);
    int add_cpu(unsigned int cpu);
    +int cpu_device_up(struct device *dev);
    void notify_cpu_starting(unsigned int cpu);
    extern void cpu_maps_update_begin(void);
    extern void cpu_maps_update_done(void);
    @@ -120,8 +120,8 @@ extern void lockdep_assert_cpus_held(void);
    extern void cpu_hotplug_disable(void);
    extern void cpu_hotplug_enable(void);
    void clear_tasks_mm_cpumask(int cpu);
    -int cpu_down(unsigned int cpu);
    int remove_cpu(unsigned int cpu);
    +int cpu_device_down(struct device *dev);
    extern void smp_shutdown_nonboot_cpus(unsigned int primary_cpu);

    #else /* CONFIG_HOTPLUG_CPU */
    diff --git a/kernel/cpu.c b/kernel/cpu.c
    index 4783d81..3084849 100644
    --- a/kernel/cpu.c
    +++ b/kernel/cpu.c
    @@ -1041,7 +1041,7 @@ static int cpu_down_maps_locked(unsigned int cpu, enum cpuhp_state target)
    return _cpu_down(cpu, 0, target);
    }

    -static int do_cpu_down(unsigned int cpu, enum cpuhp_state target)
    +static int cpu_down(unsigned int cpu, enum cpuhp_state target)
    {
    int err;

    @@ -1051,11 +1051,18 @@ static int do_cpu_down(unsigned int cpu, enum cpuhp_state target)
    return err;
    }

    -int cpu_down(unsigned int cpu)
    +/**
    + * cpu_device_down - Bring down a cpu device
    + * @dev: Pointer to the cpu device to offline
    + *
    + * This function is meant to be used by device core cpu subsystem only.
    + *
    + * Other subsystems should use remove_cpu() instead.
    + */
    +int cpu_device_down(struct device *dev)
    {
    - return do_cpu_down(cpu, CPUHP_OFFLINE);
    + return cpu_down(dev->id, CPUHP_OFFLINE);
    }
    -EXPORT_SYMBOL(cpu_down);

    int remove_cpu(unsigned int cpu)
    {
    @@ -1178,8 +1185,8 @@ static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target)
    }

    /*
    - * The caller of do_cpu_up might have raced with another
    - * caller. Ignore it for now.
    + * The caller of cpu_up() might have raced with another
    + * caller. Nothing to do.
    */
    if (st->state >= target)
    goto out;
    @@ -1223,7 +1230,7 @@ out:
    return ret;
    }

    -static int do_cpu_up(unsigned int cpu, enum cpuhp_state target)
    +static int cpu_up(unsigned int cpu, enum cpuhp_state target)
    {
    int err = 0;

    @@ -1257,11 +1264,18 @@ out:
    return err;
    }

    -int cpu_up(unsigned int cpu)
    +/**
    + * cpu_device_up - Bring up a cpu device
    + * @dev: Pointer to the cpu device to online
    + *
    + * This function is meant to be used by device core cpu subsystem only.
    + *
    + * Other subsystems should use add_cpu() instead.
    + */
    +int cpu_device_up(struct device *dev)
    {
    - return do_cpu_up(cpu, CPUHP_ONLINE);
    + return cpu_up(dev->id, CPUHP_ONLINE);
    }
    -EXPORT_SYMBOL_GPL(cpu_up);

    int add_cpu(unsigned int cpu)
    {
    @@ -1289,7 +1303,7 @@ int bringup_hibernate_cpu(unsigned int sleep_cpu)

    if (!cpu_online(sleep_cpu)) {
    pr_info("Hibernated on a CPU that is offline! Bringing CPU up.\n");
    - ret = cpu_up(sleep_cpu);
    + ret = cpu_up(sleep_cpu, CPUHP_ONLINE);
    if (ret) {
    pr_err("Failed to bring hibernate-CPU up!\n");
    return ret;
    @@ -1306,7 +1320,7 @@ void bringup_nonboot_cpus(unsigned int setup_max_cpus)
    if (num_online_cpus() >= setup_max_cpus)
    break;
    if (!cpu_online(cpu))
    - cpu_up(cpu);
    + cpu_up(cpu, CPUHP_ONLINE);
    }
    }

    @@ -2129,9 +2143,9 @@ static ssize_t write_cpuhp_target(struct device *dev,
    goto out;

    if (st->state < target)
    - ret = do_cpu_up(dev->id, target);
    + ret = cpu_up(dev->id, target);
    else
    - ret = do_cpu_down(dev->id, target);
    + ret = cpu_down(dev->id, target);
    out:
    unlock_device_hotplug();
    return ret ? ret : count;
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