LXR linux/include/linux/stop

   1#ifndef _LINUX_STOP_MACHINE
   2#define _LINUX_STOP_MACHINE
   3
   4#include <linux/cpu.h>
   5#include <linux/cpumask.h>
   6#include <linux/smp.h>
   7#include <linux/list.h>
   8
   9/*
  10 * stop_cpu[s]() is simplistic per-cpu maximum priority cpu
  11 * monopolization mechanism.  The caller can specify a non-sleeping
  12 * function to be executed on a single or multiple cpus preempting all
  13 * other processes and monopolizing those cpus until it finishes.
  14 *
  15 * Resources for this mechanism are preallocated when a cpu is brought
  16 * up and requests are guaranteed to be served as long as the target
  17 * cpus are online.
  18 */
  19typedef int (*cpu_stop_fn_t)(void *arg);
  20
  21#ifdef CONFIG_SMP
  22
  23struct cpu_stop_work {
  24        struct list_head        list;           /* cpu_stopper->works */
  25        cpu_stop_fn_t           fn;
  26        void                    *arg;
  27        struct cpu_stop_done    *done;
  28};
  29
  30int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg);
  31int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void *arg);
  32bool stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg,
  33                         struct cpu_stop_work *work_buf);
  34int stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);
  35int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);
  36void stop_machine_park(int cpu);
  37void stop_machine_unpark(int cpu);
  38
  39#else   /* CONFIG_SMP */
  40
  41#include <linux/workqueue.h>
  42
  43struct cpu_stop_work {
  44        struct work_struct      work;
  45        cpu_stop_fn_t           fn;
  46        void                    *arg;
  47};
  48
  49static inline int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg)
  50{
  51        int ret = -ENOENT;
  52        preempt_disable();
  53        if (cpu == smp_processor_id())
  54                ret = fn(arg);
  55        preempt_enable();
  56        return ret;
  57}
  58
  59static void stop_one_cpu_nowait_workfn(struct work_struct *work)
  60{
  61        struct cpu_stop_work *stwork =
  62                container_of(work, struct cpu_stop_work, work);
  63        preempt_disable();
  64        stwork->fn(stwork->arg);
  65        preempt_enable();
  66}
  67
  68static inline bool stop_one_cpu_nowait(unsigned int cpu,
  69                                       cpu_stop_fn_t fn, void *arg,
  70                                       struct cpu_stop_work *work_buf)
  71{
  72        if (cpu == smp_processor_id()) {
  73                INIT_WORK(&work_buf->work, stop_one_cpu_nowait_workfn);
  74                work_buf->fn = fn;
  75                work_buf->arg = arg;
  76                schedule_work(&work_buf->work);
  77                return true;
  78        }
  79
  80        return false;
  81}
  82
  83static inline int stop_cpus(const struct cpumask *cpumask,
  84                            cpu_stop_fn_t fn, void *arg)
  85{
  86        if (cpumask_test_cpu(raw_smp_processor_id(), cpumask))
  87                return stop_one_cpu(raw_smp_processor_id(), fn, arg);
  88        return -ENOENT;
  89}
  90
  91static inline int try_stop_cpus(const struct cpumask *cpumask,
  92                                cpu_stop_fn_t fn, void *arg)
  93{
  94        return stop_cpus(cpumask, fn, arg);
  95}
  96
  97#endif  /* CONFIG_SMP */
  98
  99/*
 100 * stop_machine "Bogolock": stop the entire machine, disable
 101 * interrupts.  This is a very heavy lock, which is equivalent to
 102 * grabbing every spinlock (and more).  So the "read" side to such a
 103 * lock is anything which disables preemption.
 104 */
 105#if defined(CONFIG_SMP) || defined(CONFIG_HOTPLUG_CPU)
 106
 107/**
 108 * stop_machine: freeze the machine on all CPUs and run this function
 109 * @fn: the function to run
 110 * @data: the data ptr for the @fn()
 111 * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
 112 *
 113 * Description: This causes a thread to be scheduled on every cpu,
 114 * each of which disables interrupts.  The result is that no one is
 115 * holding a spinlock or inside any other preempt-disabled region when
 116 * @fn() runs.
 117 *
 118 * This can be thought of as a very heavy write lock, equivalent to
 119 * grabbing every spinlock in the kernel. */
 120int stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus);
 121
 122int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data,
 123                                   const struct cpumask *cpus);
 124#else   /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */
 125
 126static inline int stop_machine(cpu_stop_fn_t fn, void *data,
 127                                 const struct cpumask *cpus)
 128{
 129        unsigned long flags;
 130        int ret;
 131        local_irq_save(flags);
 132        ret = fn(data);
 133        local_irq_restore(flags);
 134        return ret;
 135}
 136
 137static inline int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data,
 138                                                 const struct cpumask *cpus)
 139{
 140        return stop_machine(fn, data, cpus);
 141}
 142
 143#endif  /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */
 144#endif  /* _LINUX_STOP_MACHINE */
 145