include/linux/stop_machine.h

   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    diables preeempt. */
   7 #include <linux/cpu.h>
   8 #include <asm/system.h>
   9
  10 #if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP)
  11 /**
  12  * stop_machine_run: freeze the machine on all CPUs and run this function
  13  * @fn: the function to run
  14  * @data: the data ptr for the @fn()
  15  * @cpu: the cpu to run @fn() on (or any, if @cpu == NR_CPUS.
  16  *
  17  * Description: This causes a thread to be scheduled on every other cpu,
  18  * each of which disables interrupts, and finally interrupts are disabled
  19  * on the current CPU.  The result is that noone is holding a spinlock
  20  * or inside any other preempt-disabled region when @fn() runs.
  21  *
  22  * This can be thought of as a very heavy write lock, equivalent to
  23  * grabbing every spinlock in the kernel. */
  24 int stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu);
  25
  26 /**
  27  * __stop_machine_run: freeze the machine on all CPUs and run this function
  28  * @fn: the function to run
  29  * @data: the data ptr for the @fn
  30  * @cpu: the cpu to run @fn on (or any, if @cpu == NR_CPUS.
  31  *
  32  * Description: This is a special version of the above, which returns the
  33  * thread which has run @fn(): kthread_stop will return the return value
  34  * of @fn().  Used by hotplug cpu.
  35  */
  36 struct task_struct *__stop_machine_run(int (*fn)(void *), void *data,
  37                                        unsigned int cpu);
  38
  39 #else
  40
  41 static inline int stop_machine_run(int (*fn)(void *), void *data,
  42                                    unsigned int cpu)
  43 {
  44         int ret;
  45         local_irq_disable();
  46         ret = fn(data);
  47         local_irq_enable();
  48         return ret;
  49 }
  50 #endif /* CONFIG_SMP */
  51 #endif /* _LINUX_STOP_MACHINE */