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    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. */
  26 int 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  */
  37 int __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  */
  46 int 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  */
  54 void stop_machine_destroy(void);
  55
  56 #else
  57
  58 static 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
  68 static inline int stop_machine_create(void) { return 0; }
  69 static inline void stop_machine_destroy(void) { }
  70
  71 #endif /* CONFIG_SMP */
  72 #endif /* _LINUX_STOP_MACHINE */