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