LXR linux/include/linux/stop

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef _LINUX_STOP_MACHINE
   3#define _LINUX_STOP_MACHINE
   4
   5#include <linux/cpu.h>
   6#include <linux/cpumask.h>
   7#include <linux/smp.h>
   8#include <linux/list.h>
   9
  10/*
  11 * stop_cpu[s]() is simplistic per-cpu maximum priority cpu
  12 * monopolization mechanism.  The caller can specify a non-sleeping
  13 * function to be executed on a single or multiple cpus preempting all
  14 * other processes and monopolizing those cpus until it finishes.
  15 *
  16 * Resources for this mechanism are preallocated when a cpu is brought
  17 * up and requests are guaranteed to be served as long as the target
  18 * cpus are online.
  19 */
  20typedef int (*cpu_stop_fn_t)(void *arg);
  21
  22#ifdef CONFIG_SMP
  23
  24struct cpu_stop_work {
  25        struct list_head        list;           /* cpu_stopper->works */
  26        cpu_stop_fn_t           fn;
  27        unsigned long           caller;
  28        void                    *arg;
  29        struct cpu_stop_done    *done;
  30};
  31
  32int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg);
  33int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void *arg);
  34bool stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg,
  35                         struct cpu_stop_work *work_buf);
  36void stop_machine_park(int cpu);
  37void stop_machine_unpark(int cpu);
  38void stop_machine_yield(const struct cpumask *cpumask);
  39
  40extern void print_stop_info(const char *log_lvl, struct task_struct *task);
  41
  42#else   /* CONFIG_SMP */
  43
  44#include <linux/workqueue.h>
  45
  46struct cpu_stop_work {
  47        struct work_struct      work;
  48        cpu_stop_fn_t           fn;
  49        void                    *arg;
  50};
  51
  52static inline int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg)
  53{
  54        int ret = -ENOENT;
  55        preempt_disable();
  56        if (cpu == smp_processor_id())
  57                ret = fn(arg);
  58        preempt_enable();
  59        return ret;
  60}
  61
  62static void stop_one_cpu_nowait_workfn(struct work_struct *work)
  63{
  64        struct cpu_stop_work *stwork =
  65                container_of(work, struct cpu_stop_work, work);
  66        preempt_disable();
  67        stwork->fn(stwork->arg);
  68        preempt_enable();
  69}
  70
  71static inline bool stop_one_cpu_nowait(unsigned int cpu,
  72                                       cpu_stop_fn_t fn, void *arg,
  73                                       struct cpu_stop_work *work_buf)
  74{
  75        if (cpu == smp_processor_id()) {
  76                INIT_WORK(&work_buf->work, stop_one_cpu_nowait_workfn);
  77                work_buf->fn = fn;
  78                work_buf->arg = arg;
  79                schedule_work(&work_buf->work);
  80                return true;
  81        }
  82
  83        return false;
  84}
  85
  86static inline void print_stop_info(const char *log_lvl, struct task_struct *task) { }
  87
  88#endif  /* CONFIG_SMP */
  89
  90/*
  91 * stop_machine "Bogolock": stop the entire machine, disable
  92 * interrupts.  This is a very heavy lock, which is equivalent to
  93 * grabbing every spinlock (and more).  So the "read" side to such a
  94 * lock is anything which disables preemption.
  95 */
  96#if defined(CONFIG_SMP) || defined(CONFIG_HOTPLUG_CPU)
  97
  98/**
  99 * stop_machine: freeze the machine on all CPUs and run this function
 100 * @fn: the function to run
 101 * @data: the data ptr for the @fn()
 102 * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
 103 *
 104 * Description: This causes a thread to be scheduled on every cpu,
 105 * each of which disables interrupts.  The result is that no one is
 106 * holding a spinlock or inside any other preempt-disabled region when
 107 * @fn() runs.
 108 *
 109 * This can be thought of as a very heavy write lock, equivalent to
 110 * grabbing every spinlock in the kernel.
 111 *
 112 * Protects against CPU hotplug.
 113 */
 114int stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus);
 115
 116/**
 117 * stop_machine_cpuslocked: 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 * Same as above. Must be called from with in a cpus_read_lock() protected
 123 * region. Avoids nested calls to cpus_read_lock().
 124 */
 125int stop_machine_cpuslocked(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus);
 126
 127int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data,
 128                                   const struct cpumask *cpus);
 129#else   /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */
 130
 131static __always_inline int stop_machine_cpuslocked(cpu_stop_fn_t fn, void *data,
 132                                          const struct cpumask *cpus)
 133{
 134        unsigned long flags;
 135        int ret;
 136        local_irq_save(flags);
 137        ret = fn(data);
 138        local_irq_restore(flags);
 139        return ret;
 140}
 141
 142static __always_inline int
 143stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus)
 144{
 145        return stop_machine_cpuslocked(fn, data, cpus);
 146}
 147
 148static __always_inline int
 149stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data,
 150                               const struct cpumask *cpus)
 151{
 152        return stop_machine(fn, data, cpus);
 153}
 154
 155#endif  /* CONFIG_SMP || CONFIG_HOTPLUG_CPU */
 156#endif  /* _LINUX_STOP_MACHINE */
 157