LXR linux/include/linux/stop

   1#ifndef _LINUX_STOP_MACHINE
   2#define _LINUX_STOP_MACHINE
   3/* "Bogolock": stop the entire machine, disable interrupts.  This is a
   4   very heavy lock, which is equivalent to grabbing every spinlock
   5   (and more).  So the "read" side to such a lock is anything which
   6   disables preeempt. */
   7#include <linux/cpu.h>
   8#include <linux/cpumask.h>
   9#include <asm/system.h>
  10
  11#if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP)
  12
  13/**
  14 * stop_machine: freeze the machine on all CPUs and run this function
  15 * @fn: the function to run
  16 * @data: the data ptr for the @fn()
  17 * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
  18 *
  19 * Description: This causes a thread to be scheduled on every cpu,
  20 * each of which disables interrupts.  The result is that noone is
  21 * holding a spinlock or inside any other preempt-disabled region when
  22 * @fn() runs.
  23 *
  24 * This can be thought of as a very heavy write lock, equivalent to
  25 * grabbing every spinlock in the kernel. */
  26int stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
  27
  28/**
  29 * __stop_machine: freeze the machine on all CPUs and run this function
  30 * @fn: the function to run
  31 * @data: the data ptr for the @fn
  32 * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
  33 *
  34 * Description: This is a special version of the above, which assumes cpus
  35 * won't come or go while it's being called.  Used by hotplug cpu.
  36 */
  37int __stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
  38
  39/**
  40 * stop_machine_create: create all stop_machine threads
  41 *
  42 * Description: This causes all stop_machine threads to be created before
  43 * stop_machine actually gets called. This can be used by subsystems that
  44 * need a non failing stop_machine infrastructure.
  45 */
  46int stop_machine_create(void);
  47
  48/**
  49 * stop_machine_destroy: destroy all stop_machine threads
  50 *
  51 * Description: This causes all stop_machine threads which were created with
  52 * stop_machine_create to be destroyed again.
  53 */
  54void stop_machine_destroy(void);
  55
  56#else
  57
  58static inline int stop_machine(int (*fn)(void *), void *data,
  59                               const struct cpumask *cpus)
  60{
  61        int ret;
  62        local_irq_disable();
  63        ret = fn(data);
  64        local_irq_enable();
  65        return ret;
  66}
  67
  68static inline int stop_machine_create(void) { return 0; }
  69static inline void stop_machine_destroy(void) { }
  70
  71#endif /* CONFIG_SMP */
  72#endif /* _LINUX_STOP_MACHINE */
  73