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review.shift-gmbh.com / SHIFTPHONES / mainline / linux / 319b6ffc6df892e4ccffff823cc5521a4a5d2dca / . / kernel / smpboot.c
blob: e1a797e028a320d62c01e77a47f533e0998adaa3 [file] [log] [blame]
Thomas Gleixner38498a62012-04-20 13:05:44 +0000[diff] [blame]1/*
2 * Common SMP CPU bringup/teardown functions
3 */
Thomas Gleixner29d5e042012-04-20 13:05:45 +0000[diff] [blame]4#include <linux/err.h>
5#include <linux/smp.h>
Thomas Gleixner38498a62012-04-20 13:05:44 +0000[diff] [blame]6#include <linux/init.h>
Thomas Gleixner29d5e042012-04-20 13:05:45 +0000[diff] [blame]7#include <linux/sched.h>
8#include <linux/percpu.h>
Thomas Gleixner38498a62012-04-20 13:05:44 +0000[diff] [blame]9
10#include "smpboot.h"
11
Thomas Gleixner29d5e042012-04-20 13:05:45 +0000[diff] [blame]12#ifdef CONFIG_GENERIC_SMP_IDLE_THREAD
Thomas Gleixner29d5e042012-04-20 13:05:45 +0000[diff] [blame]13/*
14 * For the hotplug case we keep the task structs around and reuse
15 * them.
16 */
17static DEFINE_PER_CPU(struct task_struct *, idle_threads);
18
Suresh Siddha3bb5d2e2012-04-20 17:08:50 -0700[diff] [blame]19struct task_struct * __cpuinit idle_thread_get(unsigned int cpu)
Thomas Gleixner29d5e042012-04-20 13:05:45 +0000[diff] [blame]20{
21 struct task_struct *tsk = per_cpu(idle_threads, cpu);
22
23 if (!tsk)
Suresh Siddha3bb5d2e2012-04-20 17:08:50 -0700[diff] [blame]24 return ERR_PTR(-ENOMEM);
Thomas Gleixner29d5e042012-04-20 13:05:45 +0000[diff] [blame]25 init_idle(tsk, cpu);
26 return tsk;
27}
28
Thomas Gleixner29d5e042012-04-20 13:05:45 +0000[diff] [blame]29void __init idle_thread_set_boot_cpu(void)
30{
31 per_cpu(idle_threads, smp_processor_id()) = current;
32}
33
Suresh Siddha3bb5d2e2012-04-20 17:08:50 -0700[diff] [blame]34static inline void idle_init(unsigned int cpu)
35{
36 struct task_struct *tsk = per_cpu(idle_threads, cpu);
37
38 if (!tsk) {
39 tsk = fork_idle(cpu);
40 if (IS_ERR(tsk))
41 pr_err("SMP: fork_idle() failed for CPU %u\n", cpu);
42 else
43 per_cpu(idle_threads, cpu) = tsk;
44 }
45}
46
Thomas Gleixner29d5e042012-04-20 13:05:45 +0000[diff] [blame]47/**
48 * idle_thread_init - Initialize the idle thread for a cpu
49 * @cpu: The cpu for which the idle thread should be initialized
50 *
51 * Creates the thread if it does not exist.
52 */
Suresh Siddha3bb5d2e2012-04-20 17:08:50 -0700[diff] [blame]53void __init idle_threads_init(void)
Thomas Gleixner29d5e042012-04-20 13:05:45 +0000[diff] [blame]54{
Suresh Siddha3bb5d2e2012-04-20 17:08:50 -0700[diff] [blame]55 unsigned int cpu;
Thomas Gleixner29d5e042012-04-20 13:05:45 +0000[diff] [blame]56
Suresh Siddha3bb5d2e2012-04-20 17:08:50 -0700[diff] [blame]57 for_each_possible_cpu(cpu) {
58 if (cpu != smp_processor_id())
59 idle_init(cpu);
Thomas Gleixner29d5e042012-04-20 13:05:45 +0000[diff] [blame]60 }
Thomas Gleixner29d5e042012-04-20 13:05:45 +0000[diff] [blame]61}
Thomas Gleixner29d5e042012-04-20 13:05:45 +0000[diff] [blame]62#endif