linux/include/linux/stop_machine.h
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   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);
  31void stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg,
  32                         struct cpu_stop_work *work_buf);
  33int stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);
  34int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);
  35
  36#else   /* CONFIG_SMP */
  37
  38#include <linux/workqueue.h>
  39
  40struct cpu_stop_work {
  41        struct work_struct      work;
  42        cpu_stop_fn_t           fn;
  43        void                    *arg;
  44};
  45
  46static inline int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg)
  47{
  48        int ret = -ENOENT;
  49        preempt_disable();
  50        if (cpu == smp_processor_id())
  51                ret = fn(arg);
  52        preempt_enable();
  53        return ret;
  54}
  55
  56static void stop_one_cpu_nowait_workfn(struct work_struct *work)
  57{
  58        struct cpu_stop_work *stwork =
  59                container_of(work, struct cpu_stop_work, work);
  60        preempt_disable();
  61        stwork->fn(stwork->arg);
  62        preempt_enable();
  63}
  64
  65static inline void stop_one_cpu_nowait(unsigned int cpu,
  66                                       cpu_stop_fn_t fn, void *arg,
  67                                       struct cpu_stop_work *work_buf)
  68{
  69        if (cpu == smp_processor_id()) {
  70                INIT_WORK(&work_buf->work, stop_one_cpu_nowait_workfn);
  71                work_buf->fn = fn;
  72                work_buf->arg = arg;
  73                schedule_work(&work_buf->work);
  74        }
  75}
  76
  77static inline int stop_cpus(const struct cpumask *cpumask,
  78                            cpu_stop_fn_t fn, void *arg)
  79{
  80        if (cpumask_test_cpu(raw_smp_processor_id(), cpumask))
  81                return stop_one_cpu(raw_smp_processor_id(), fn, arg);
  82        return -ENOENT;
  83}
  84
  85static inline int try_stop_cpus(const struct cpumask *cpumask,
  86                                cpu_stop_fn_t fn, void *arg)
  87{
  88        return stop_cpus(cpumask, fn, arg);
  89}
  90
  91#endif  /* CONFIG_SMP */
  92
  93/*
  94 * stop_machine "Bogolock": stop the entire machine, disable
  95 * interrupts.  This is a very heavy lock, which is equivalent to
  96 * grabbing every spinlock (and more).  So the "read" side to such a
  97 * lock is anything which disables preemption.
  98 */
  99#if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP)
 100
 101/**
 102 * stop_machine: freeze the machine on all CPUs and run this function
 103 * @fn: the function to run
 104 * @data: the data ptr for the @fn()
 105 * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
 106 *
 107 * Description: This causes a thread to be scheduled on every cpu,
 108 * each of which disables interrupts.  The result is that no one is
 109 * holding a spinlock or inside any other preempt-disabled region when
 110 * @fn() runs.
 111 *
 112 * This can be thought of as a very heavy write lock, equivalent to
 113 * grabbing every spinlock in the kernel. */
 114int stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
 115
 116/**
 117 * __stop_machine: freeze the machine on all CPUs and run this function
 118 * @fn: the function to run
 119 * @data: the data ptr for the @fn
 120 * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
 121 *
 122 * Description: This is a special version of the above, which assumes cpus
 123 * won't come or go while it's being called.  Used by hotplug cpu.
 124 */
 125int __stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
 126
 127int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data,
 128                                   const struct cpumask *cpus);
 129
 130#else    /* CONFIG_STOP_MACHINE && CONFIG_SMP */
 131
 132static inline int __stop_machine(int (*fn)(void *), void *data,
 133                                 const struct cpumask *cpus)
 134{
 135        unsigned long flags;
 136        int ret;
 137        local_irq_save(flags);
 138        ret = fn(data);
 139        local_irq_restore(flags);
 140        return ret;
 141}
 142
 143static inline int stop_machine(int (*fn)(void *), void *data,
 144                               const struct cpumask *cpus)
 145{
 146        return __stop_machine(fn, data, cpus);
 147}
 148
 149static inline int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data,
 150                                                 const struct cpumask *cpus)
 151{
 152        return __stop_machine(fn, data, cpus);
 153}
 154
 155#endif  /* CONFIG_STOP_MACHINE && CONFIG_SMP */
 156#endif  /* _LINUX_STOP_MACHINE */
 157
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