| 1 | |
| 2 | * Common SMP CPU bringup/teardown functions
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| 3 |
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| 4 | #include <linux/err.h>
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| 5 | #include <linux/smp.h>
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| 6 | #include <linux/init.h>
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| 7 | #include <linux/sched.h>
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| 8 | #include <linux/percpu.h>
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| 9 |
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| 10 | #include "smpboot.h"
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| 11 |
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| 12 | #ifdef CONFIG_GENERIC_SMP_IDLE_THREAD
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| 13 | |
| 14 | * For the hotplug case we keep the task structs around and reuse
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| 15 | * them.
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| 16 |
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| 17 | static DEFINE_PER_CPU(struct task_struct *, idle_threads);
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| 18 |
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| 19 | struct task_struct * __cpuinit idle_thread_get(unsigned int cpu)
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| 20 | {
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| 21 | struct task_struct *tsk = per_cpu(idle_threads, cpu);
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| 22 |
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| 23 | if (!tsk)
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| 24 | return ERR_PTR(-ENOMEM);
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| 25 | init_idle(tsk, cpu);
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| 26 | return tsk;
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| 27 | }
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| 28 |
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| 29 | void __init idle_thread_set_boot_cpu(void)
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| 30 | {
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| 31 | per_cpu(idle_threads, smp_processor_id()) = current;
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| 32 | }
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| 33 |
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| 34 | |
| 35 | * idle_init - Initialize the idle thread for a cpu
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| 36 | * @cpu: The cpu for which the idle thread should be initialized
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| 37 | *
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| 38 | * Creates the thread if it does not exist.
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| 39 |
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| 40 | static inline void idle_init(unsigned int cpu)
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| 41 | {
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| 42 | struct task_struct *tsk = per_cpu(idle_threads, cpu);
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| 43 |
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| 44 | if (!tsk) {
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| 45 | tsk = fork_idle(cpu);
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| 46 | if (IS_ERR(tsk))
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| 47 | pr_err("SMP: fork_idle() failed for CPU %u\n", cpu);
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| 48 | else
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| 49 | per_cpu(idle_threads, cpu) = tsk;
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| 50 | }
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| 51 | }
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| 52 |
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| 53 | |
| 54 | * idle_threads_init - Initialize idle threads for all cpus
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| 55 |
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| 56 | void __init idle_threads_init(void)
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| 57 | {
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| 58 | unsigned int cpu, boot_cpu;
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| 59 |
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| 60 | boot_cpu = smp_processor_id();
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| 61 |
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| 62 | for_each_possible_cpu(cpu) {
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| 63 | if (cpu != boot_cpu)
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| 64 | idle_init(cpu);
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| 65 | }
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| 66 | }
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| 67 | #endif
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