On 3/1/16 2:52 PM, tip-bot for Thomas Gleixner wrote:
> Commit-ID: ba997462435f48ad1501320e9da8770fd40c59b1
> Gitweb: http://git.kernel.org/tip/ba997462435f48ad1501320e9da8770fd40c59b1
> Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> AuthorDate: Fri, 26 Feb 2016 18:43:24 +0000
> Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> CommitDate: Tue, 1 Mar 2016 20:36:53 +0100
>
> cpu/hotplug: Restructure cpu_up code
>
> Split out into separate functions, so we can convert it to a state machine.
>
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: linux-arch@xxxxxxxxxxxxxxx
> Cc: Rik van Riel <riel@xxxxxxxxxx>
> Cc: Rafael Wysocki <rafael.j.wysocki@xxxxxxxxx>
> Cc: "Srivatsa S. Bhat" <srivatsa@xxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
> Cc: Sebastian Siewior <bigeasy@xxxxxxxxxxxxx>
> Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
> Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
> Cc: Tejun Heo <tj@xxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Paul McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Cc: Paul Turner <pjt@xxxxxxxxxx>
> Link: http://lkml.kernel.org/r/20160226182340.429389195@xxxxxxxxxxxxx
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> ---
Reviewed-by: Srivatsa S. Bhat <srivatsa@xxxxxxxxxxxxx>
Regards,
Srivatsa S. Bhat
> kernel/cpu.c | 69 +++++++++++++++++++++++++++++++++++++++++-------------------
> 1 file changed, 47 insertions(+), 22 deletions(-)
>
> diff --git a/kernel/cpu.c b/kernel/cpu.c
> index 41a6cb8..15a4136 100644
> --- a/kernel/cpu.c
> +++ b/kernel/cpu.c
> @@ -228,6 +228,43 @@ static int cpu_notify(unsigned long val, unsigned int cpu)
> return __cpu_notify(val, cpu, -1, NULL);
> }
>
> +/* Notifier wrappers for transitioning to state machine */
> +static int notify_prepare(unsigned int cpu)
> +{
> + int nr_calls = 0;
> + int ret;
> +
> + ret = __cpu_notify(CPU_UP_PREPARE, cpu, -1, &nr_calls);
> + if (ret) {
> + nr_calls--;
> + printk(KERN_WARNING "%s: attempt to bring up CPU %u failed\n",
> + __func__, cpu);
> + __cpu_notify(CPU_UP_CANCELED, cpu, nr_calls, NULL);
> + }
> + return ret;
> +}
> +
> +static int notify_online(unsigned int cpu)
> +{
> + cpu_notify(CPU_ONLINE, cpu);
> + return 0;
> +}
> +
> +static int bringup_cpu(unsigned int cpu)
> +{
> + struct task_struct *idle = idle_thread_get(cpu);
> + int ret;
> +
> + /* Arch-specific enabling code. */
> + ret = __cpu_up(cpu, idle);
> + if (ret) {
> + cpu_notify(CPU_UP_CANCELED, cpu);
> + return ret;
> + }
> + BUG_ON(!cpu_online(cpu));
> + return 0;
> +}
> +
> #ifdef CONFIG_HOTPLUG_CPU
>
> static void cpu_notify_nofail(unsigned long val, unsigned int cpu)
> @@ -481,7 +518,7 @@ void smpboot_thread_init(void)
> static int _cpu_up(unsigned int cpu, int tasks_frozen)
> {
> struct task_struct *idle;
> - int ret, nr_calls = 0;
> + int ret;
>
> cpu_hotplug_begin();
>
> @@ -496,33 +533,21 @@ static int _cpu_up(unsigned int cpu, int tasks_frozen)
> goto out;
> }
>
> + cpuhp_tasks_frozen = tasks_frozen;
> +
> ret = smpboot_create_threads(cpu);
> if (ret)
> goto out;
>
> - cpuhp_tasks_frozen = tasks_frozen;
> -
> - ret = __cpu_notify(CPU_UP_PREPARE, cpu, -1, &nr_calls);
> - if (ret) {
> - nr_calls--;
> - pr_warn("%s: attempt to bring up CPU %u failed\n",
> - __func__, cpu);
> - goto out_notify;
> - }
> -
> - /* Arch-specific enabling code. */
> - ret = __cpu_up(cpu, idle);
> -
> - if (ret != 0)
> - goto out_notify;
> - BUG_ON(!cpu_online(cpu));
> + ret = notify_prepare(cpu);
> + if (ret)
> + goto out;
>
> - /* Now call notifier in preparation. */
> - cpu_notify(CPU_ONLINE, cpu);
> + ret = bringup_cpu(cpu);
> + if (ret)
> + goto out;
>
> -out_notify:
> - if (ret != 0)
> - __cpu_notify(CPU_UP_CANCELED, cpu, nr_calls, NULL);
> + notify_online(cpu);
> out:
> cpu_hotplug_done();
>
>
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