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Date: Sun, 29 Apr 2012 08:51:46 +1000
From: Benjamin Herrenschmidt <benh@...nel.crashing.org>
To: mingo@...nel.org, hpa@...or.com, linux-kernel@...r.kernel.org,
rusty@...tcorp.com.au, peterz@...radead.org,
srivatsa.bhat@...ux.vnet.ibm.com, paulmck@...ux.vnet.ibm.com,
tglx@...utronix.de
Cc: linux-tip-commits@...r.kernel.org
Subject: Re: [tip:smp/hotplug] powerpc: Use generic idle thread allocation
On Sat, 2012-04-28 at 02:07 -0700, tip-bot for Thomas Gleixner wrote:
> Commit-ID: 17e32eacc3543c25a4377bb7ce54026e38db7d20
> Gitweb: http://git.kernel.org/tip/17e32eacc3543c25a4377bb7ce54026e38db7d20
> Author: Thomas Gleixner <tglx@...utronix.de>
> AuthorDate: Fri, 20 Apr 2012 13:05:48 +0000
> Committer: Thomas Gleixner <tglx@...utronix.de>
> CommitDate: Thu, 26 Apr 2012 12:06:10 +0200
>
> powerpc: Use generic idle thread allocation
Ah good, sorry I missed the previous batch. This is the logical
next step after I changed us to do the same as x86 :)
I'll give it a spin tomorrow (monday my time).
Cheers,
Ben.
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Rusty Russell <rusty@...tcorp.com.au>
> Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
> Cc: Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com>
> Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
> Link: http://lkml.kernel.org/r/20120420124557.311212868@linutronix.de
> ---
> arch/powerpc/Kconfig | 1 +
> arch/powerpc/kernel/smp.c | 74 +++-----------------------------------------
> 2 files changed, 6 insertions(+), 69 deletions(-)
>
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index feab3ba..c815535 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -144,6 +144,7 @@ config PPC
> select HAVE_BPF_JIT if (PPC64 && NET)
> select HAVE_ARCH_JUMP_LABEL
> select ARCH_HAVE_NMI_SAFE_CMPXCHG
> + select GENERIC_SMP_IDLE_THREAD
>
> config EARLY_PRINTK
> bool
> diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
> index d38030f..e4cb343 100644
> --- a/arch/powerpc/kernel/smp.c
> +++ b/arch/powerpc/kernel/smp.c
> @@ -57,27 +57,9 @@
> #define DBG(fmt...)
> #endif
>
> -
> -/* Store all idle threads, this can be reused instead of creating
> -* a new thread. Also avoids complicated thread destroy functionality
> -* for idle threads.
> -*/
> #ifdef CONFIG_HOTPLUG_CPU
> -/*
> - * Needed only for CONFIG_HOTPLUG_CPU because __cpuinitdata is
> - * removed after init for !CONFIG_HOTPLUG_CPU.
> - */
> -static DEFINE_PER_CPU(struct task_struct *, idle_thread_array);
> -#define get_idle_for_cpu(x) (per_cpu(idle_thread_array, x))
> -#define set_idle_for_cpu(x, p) (per_cpu(idle_thread_array, x) = (p))
> -
> /* State of each CPU during hotplug phases */
> static DEFINE_PER_CPU(int, cpu_state) = { 0 };
> -
> -#else
> -static struct task_struct *idle_thread_array[NR_CPUS] __cpuinitdata ;
> -#define get_idle_for_cpu(x) (idle_thread_array[(x)])
> -#define set_idle_for_cpu(x, p) (idle_thread_array[(x)] = (p))
> #endif
>
> struct thread_info *secondary_ti;
> @@ -429,57 +411,16 @@ int generic_check_cpu_restart(unsigned int cpu)
> }
> #endif
>
> -struct create_idle {
> - struct work_struct work;
> - struct task_struct *idle;
> - struct completion done;
> - int cpu;
> -};
> -
> -static void __cpuinit do_fork_idle(struct work_struct *work)
> +static void cpu_idle_thread_init(unsigned int cpu, struct task_struct *idle)
> {
> - struct create_idle *c_idle =
> - container_of(work, struct create_idle, work);
> -
> - c_idle->idle = fork_idle(c_idle->cpu);
> - complete(&c_idle->done);
> -}
> -
> -static int __cpuinit create_idle(unsigned int cpu)
> -{
> - struct thread_info *ti;
> - struct create_idle c_idle = {
> - .cpu = cpu,
> - .done = COMPLETION_INITIALIZER_ONSTACK(c_idle.done),
> - };
> - INIT_WORK_ONSTACK(&c_idle.work, do_fork_idle);
> -
> - c_idle.idle = get_idle_for_cpu(cpu);
> -
> - /* We can't use kernel_thread since we must avoid to
> - * reschedule the child. We use a workqueue because
> - * we want to fork from a kernel thread, not whatever
> - * userspace process happens to be trying to online us.
> - */
> - if (!c_idle.idle) {
> - schedule_work(&c_idle.work);
> - wait_for_completion(&c_idle.done);
> - } else
> - init_idle(c_idle.idle, cpu);
> - if (IS_ERR(c_idle.idle)) {
> - pr_err("Failed fork for CPU %u: %li", cpu, PTR_ERR(c_idle.idle));
> - return PTR_ERR(c_idle.idle);
> - }
> - ti = task_thread_info(c_idle.idle);
> + struct thread_info *ti = task_thread_info(idle);
>
> #ifdef CONFIG_PPC64
> - paca[cpu].__current = c_idle.idle;
> + paca[cpu].__current = idle;
> paca[cpu].kstack = (unsigned long)ti + THREAD_SIZE - STACK_FRAME_OVERHEAD;
> #endif
> ti->cpu = cpu;
> - current_set[cpu] = ti;
> -
> - return 0;
> + secondary_ti = current_set[cpu] = ti;
> }
>
> int __cpuinit __cpu_up(unsigned int cpu, struct task_struct *tidle)
> @@ -490,12 +431,7 @@ int __cpuinit __cpu_up(unsigned int cpu, struct task_struct *tidle)
> (smp_ops->cpu_bootable && !smp_ops->cpu_bootable(cpu)))
> return -EINVAL;
>
> - /* Make sure we have an idle thread */
> - rc = create_idle(cpu);
> - if (rc)
> - return rc;
> -
> - secondary_ti = current_set[cpu];
> + cpu_idle_thread_init(cpu, tidle);
>
> /* Make sure callin-map entry is 0 (can be leftover a CPU
> * hotplug
> --
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