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);
  32void 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);
  36
  37#else   /* CONFIG_SMP */
  38
  39#include <linux/workqueue.h>
  40
  41struct cpu_stop_work {
  42        struct work_struct      work;
  43        cpu_stop_fn_t           fn;
  44        void                    *arg;
  45};
  46
  47static inline int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg)
  48{
  49        int ret = -ENOENT;
  50        preempt_disable();
  51        if (cpu == smp_processor_id())
  52                ret = fn(arg);
  53        preempt_enable();
  54        return ret;
  55}
  56
  57static void stop_one_cpu_nowait_workfn(struct work_struct *work)
  58{
  59        struct cpu_stop_work *stwork =
  60                container_of(work, struct cpu_stop_work, work);
  61        preempt_disable();
  62        stwork->fn(stwork->arg);
  63        preempt_enable();
  64}
  65
  66static inline void stop_one_cpu_nowait(unsigned int cpu,
  67                                       cpu_stop_fn_t fn, void *arg,
  68                                       struct cpu_stop_work *work_buf)
  69{
  70        if (cpu == smp_processor_id()) {
  71                INIT_WORK(&work_buf->work, stop_one_cpu_nowait_workfn);
  72                work_buf->fn = fn;
  73                work_buf->arg = arg;
  74                schedule_work(&work_buf->work);
  75        }
  76}
  77
  78static inline int stop_cpus(const struct cpumask *cpumask,
  79                            cpu_stop_fn_t fn, void *arg)
  80{
  81        if (cpumask_test_cpu(raw_smp_processor_id(), cpumask))
  82                return stop_one_cpu(raw_smp_processor_id(), fn, arg);
  83        return -ENOENT;
  84}
  85
  86static inline int try_stop_cpus(const struct cpumask *cpumask,
  87                                cpu_stop_fn_t fn, void *arg)
  88{
  89        return stop_cpus(cpumask, fn, arg);
  90}
  91
  92#endif  /* CONFIG_SMP */
  93
  94/*
  95 * stop_machine "Bogolock": stop the entire machine, disable
  96 * interrupts.  This is a very heavy lock, which is equivalent to
  97 * grabbing every spinlock (and more).  So the "read" side to such a
  98 * lock is anything which disables preemption.
  99 */
 100#if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP)
 101
 102/**
 103 * stop_machine: freeze the machine on all CPUs and run this function
 104 * @fn: the function to run
 105 * @data: the data ptr for the @fn()
 106 * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
 107 *
 108 * Description: This causes a thread to be scheduled on every cpu,
 109 * each of which disables interrupts.  The result is that no one is
 110 * holding a spinlock or inside any other preempt-disabled region when
 111 * @fn() runs.
 112 *
 113 * This can be thought of as a very heavy write lock, equivalent to
 114 * grabbing every spinlock in the kernel. */
 115int stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
 116
 117/**
 118 * __stop_machine: freeze the machine on all CPUs and run this function
 119 * @fn: the function to run
 120 * @data: the data ptr for the @fn
 121 * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
 122 *
 123 * Description: This is a special version of the above, which assumes cpus
 124 * won't come or go while it's being called.  Used by hotplug cpu.
 125 */
 126int __stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
 127
 128int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data,
 129                                   const struct cpumask *cpus);
 130
 131#else    /* CONFIG_STOP_MACHINE && CONFIG_SMP */
 132
 133static inline int __stop_machine(int (*fn)(void *), void *data,
 134                                 const struct cpumask *cpus)
 135{
 136        unsigned long flags;
 137        int ret;
 138        local_irq_save(flags);
 139        ret = fn(data);
 140        local_irq_restore(flags);
 141        return ret;
 142}
 143
 144static inline int stop_machine(int (*fn)(void *), void *data,
 145                               const struct cpumask *cpus)
 146{
 147        return __stop_machine(fn, data, cpus);
 148}
 149
 150static inline int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data,
 151                                                 const struct cpumask *cpus)
 152{
 153        return __stop_machine(fn, data, cpus);
 154}
 155
 156#endif  /* CONFIG_STOP_MACHINE && CONFIG_SMP */
 157#endif  /* _LINUX_STOP_MACHINE */
 158