Thomas Gleixner | 38498a6 | 2012-04-20 13:05:44 +0000 | [diff] [blame] | 1 | /* |
| 2 | * Common SMP CPU bringup/teardown functions |
| 3 | */ |
Thomas Gleixner | 29d5e04 | 2012-04-20 13:05:45 +0000 | [diff] [blame^] | 4 | #include <linux/err.h> |
| 5 | #include <linux/smp.h> |
Thomas Gleixner | 38498a6 | 2012-04-20 13:05:44 +0000 | [diff] [blame] | 6 | #include <linux/init.h> |
Thomas Gleixner | 29d5e04 | 2012-04-20 13:05:45 +0000 | [diff] [blame^] | 7 | #include <linux/sched.h> |
| 8 | #include <linux/percpu.h> |
| 9 | #include <linux/workqueue.h> |
Thomas Gleixner | 38498a6 | 2012-04-20 13:05:44 +0000 | [diff] [blame] | 10 | |
| 11 | #include "smpboot.h" |
| 12 | |
Thomas Gleixner | 29d5e04 | 2012-04-20 13:05:45 +0000 | [diff] [blame^] | 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 | |
Thomas Gleixner | 38498a6 | 2012-04-20 13:05:44 +0000 | [diff] [blame] | 90 | /** |
| 91 | * smpboot_prepare - generic smpboot preparation |
| 92 | */ |
| 93 | int __cpuinit smpboot_prepare(unsigned int cpu) |
| 94 | { |
Thomas Gleixner | 29d5e04 | 2012-04-20 13:05:45 +0000 | [diff] [blame^] | 95 | return idle_thread_init(cpu); |
Thomas Gleixner | 38498a6 | 2012-04-20 13:05:44 +0000 | [diff] [blame] | 96 | } |