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);
  36void stop_machine_park(int cpu);
  37
  38#else   /* CONFIG_SMP */
  39
  40#include <linux/workqueue.h>
  41
  42struct cpu_stop_work {
  43        struct work_struct      work;
  44        cpu_stop_fn_t           fn;
  45        void                    *arg;
  46};
  47
  48static inline int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg)
  49{
  50        int ret = -ENOENT;
  51        preempt_disable();
  52        if (cpu == smp_processor_id())
  53                ret = fn(arg);
  54        preempt_enable();
  55        return ret;
  56}
  57
  58static void stop_one_cpu_nowait_workfn(struct work_struct *work)
  59{
  60        struct cpu_stop_work *stwork =
  61                container_of(work, struct cpu_stop_work, work);
  62        preempt_disable();
  63        stwork->fn(stwork->arg);
  64        preempt_enable();
  65}
  66
  67static inline void stop_one_cpu_nowait(unsigned int cpu,
  68                                       cpu_stop_fn_t fn, void *arg,
  69                                       struct cpu_stop_work *work_buf)
  70{
  71        if (cpu == smp_processor_id()) {
  72                INIT_WORK(&work_buf->work, stop_one_cpu_nowait_workfn);
  73                work_buf->fn = fn;
  74                work_buf->arg = arg;
  75                schedule_work(&work_buf->work);
  76        }
  77}
  78
  79static inline int stop_cpus(const struct cpumask *cpumask,
  80                            cpu_stop_fn_t fn, void *arg)
  81{
  82        if (cpumask_test_cpu(raw_smp_processor_id(), cpumask))
  83                return stop_one_cpu(raw_smp_processor_id(), fn, arg);
  84        return -ENOENT;
  85}
  86
  87static inline int try_stop_cpus(const struct cpumask *cpumask,
  88                                cpu_stop_fn_t fn, void *arg)
  89{
  90        return stop_cpus(cpumask, fn, arg);
  91}
  92
  93#endif  /* CONFIG_SMP */
  94
  95/*
  96 * stop_machine "Bogolock": stop the entire machine, disable
  97 * interrupts.  This is a very heavy lock, which is equivalent to
  98 * grabbing every spinlock (and more).  So the "read" side to such a
  99 * lock is anything which disables preemption.
 100 */
 101#if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP)
 102
 103/**
 104 * stop_machine: freeze the machine on all CPUs and run this function
 105 * @fn: the function to run
 106 * @data: the data ptr for the @fn()
 107 * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
 108 *
 109 * Description: This causes a thread to be scheduled on every cpu,
 110 * each of which disables interrupts.  The result is that no one is
 111 * holding a spinlock or inside any other preempt-disabled region when
 112 * @fn() runs.
 113 *
 114 * This can be thought of as a very heavy write lock, equivalent to
 115 * grabbing every spinlock in the kernel. */
 116int stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
 117
 118/**
 119 * __stop_machine: freeze the machine on all CPUs and run this function
 120 * @fn: the function to run
 121 * @data: the data ptr for the @fn
 122 * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
 123 *
 124 * Description: This is a special version of the above, which assumes cpus
 125 * won't come or go while it's being called.  Used by hotplug cpu.
 126 */
 127int __stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
 128
 129int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data,
 130                                   const struct cpumask *cpus);
 131
 132#else    /* CONFIG_STOP_MACHINE && CONFIG_SMP */
 133
 134static inline int __stop_machine(int (*fn)(void *), void *data,
 135                                 const struct cpumask *cpus)
 136{
 137        unsigned long flags;
 138        int ret;
 139        local_irq_save(flags);
 140        ret = fn(data);
 141        local_irq_restore(flags);
 142        return ret;
 143}
 144
 145static inline int stop_machine(int (*fn)(void *), void *data,
 146                               const struct cpumask *cpus)
 147{
 148        return __stop_machine(fn, data, cpus);
 149}
 150
 151static inline int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data,
 152                                                 const struct cpumask *cpus)
 153{
 154        return __stop_machine(fn, data, cpus);
 155}
 156
 157#endif  /* CONFIG_STOP_MACHINE && CONFIG_SMP */
 158#endif  /* _LINUX_STOP_MACHINE */
 159