Commit | Line | Data |
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38498a67 TG |
1 | /* |
2 | * Common SMP CPU bringup/teardown functions | |
3 | */ | |
29d5e047 TG |
4 | #include <linux/err.h> |
5 | #include <linux/smp.h> | |
38498a67 | 6 | #include <linux/init.h> |
29d5e047 TG |
7 | #include <linux/sched.h> |
8 | #include <linux/percpu.h> | |
9 | #include <linux/workqueue.h> | |
38498a67 TG |
10 | |
11 | #include "smpboot.h" | |
12 | ||
29d5e047 TG |
13 | #ifdef CONFIG_GENERIC_SMP_IDLE_THREAD |
14 | struct create_idle { | |
15 | struct work_struct work; | |
16 | struct task_struct *idle; | |
17 | struct completion done; | |
18 | unsigned int cpu; | |
19 | }; | |
20 | ||
21 | static void __cpuinit do_fork_idle(struct work_struct *work) | |
22 | { | |
23 | struct create_idle *c = container_of(work, struct create_idle, work); | |
24 | ||
25 | c->idle = fork_idle(c->cpu); | |
26 | complete(&c->done); | |
27 | } | |
28 | ||
29 | static struct task_struct * __cpuinit idle_thread_create(unsigned int cpu) | |
30 | { | |
31 | struct create_idle c_idle = { | |
32 | .cpu = cpu, | |
33 | .done = COMPLETION_INITIALIZER_ONSTACK(c_idle.done), | |
34 | }; | |
35 | ||
36 | INIT_WORK_ONSTACK(&c_idle.work, do_fork_idle); | |
37 | schedule_work(&c_idle.work); | |
38 | wait_for_completion(&c_idle.done); | |
39 | destroy_work_on_stack(&c_idle.work); | |
40 | return c_idle.idle; | |
41 | } | |
42 | ||
43 | /* | |
44 | * For the hotplug case we keep the task structs around and reuse | |
45 | * them. | |
46 | */ | |
47 | static DEFINE_PER_CPU(struct task_struct *, idle_threads); | |
48 | ||
49 | static inline struct task_struct *get_idle_for_cpu(unsigned int cpu) | |
50 | { | |
51 | struct task_struct *tsk = per_cpu(idle_threads, cpu); | |
52 | ||
53 | if (!tsk) | |
54 | return idle_thread_create(cpu); | |
55 | init_idle(tsk, cpu); | |
56 | return tsk; | |
57 | } | |
58 | ||
59 | struct task_struct * __cpuinit idle_thread_get(unsigned int cpu) | |
60 | { | |
61 | return per_cpu(idle_threads, cpu); | |
62 | } | |
63 | ||
64 | void __init idle_thread_set_boot_cpu(void) | |
65 | { | |
66 | per_cpu(idle_threads, smp_processor_id()) = current; | |
67 | } | |
68 | ||
69 | /** | |
70 | * idle_thread_init - Initialize the idle thread for a cpu | |
71 | * @cpu: The cpu for which the idle thread should be initialized | |
72 | * | |
73 | * Creates the thread if it does not exist. | |
74 | */ | |
75 | static int __cpuinit idle_thread_init(unsigned int cpu) | |
76 | { | |
77 | struct task_struct *idle = get_idle_for_cpu(cpu); | |
78 | ||
79 | if (IS_ERR(idle)) { | |
80 | printk(KERN_ERR "failed fork for CPU %u\n", cpu); | |
81 | return PTR_ERR(idle); | |
82 | } | |
83 | per_cpu(idle_threads, cpu) = idle; | |
84 | return 0; | |
85 | } | |
86 | #else | |
87 | static inline int idle_thread_init(unsigned int cpu) { return 0; } | |
88 | #endif | |
89 | ||
38498a67 TG |
90 | /** |
91 | * smpboot_prepare - generic smpboot preparation | |
92 | */ | |
93 | int __cpuinit smpboot_prepare(unsigned int cpu) | |
94 | { | |
29d5e047 | 95 | return idle_thread_init(cpu); |
38498a67 | 96 | } |