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 <linux/cpumask.h>
   9 #include <asm/system.h>
  10
  11 #if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP)
  12
  13 /* Deprecated, but useful for transition. */
  14 #define ALL_CPUS ~0U
  15
  16 /**
  17  * stop_machine: freeze the machine on all CPUs and run this function
  18  * @fn: the function to run
  19  * @data: the data ptr for the @fn()
  20  * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
  21  *
  22  * Description: This causes a thread to be scheduled on every cpu,
  23  * each of which disables interrupts.  The result is that noone is
  24  * holding a spinlock or inside any other preempt-disabled region when
  25  * @fn() runs.
  26  *
  27  * This can be thought of as a very heavy write lock, equivalent to
  28  * grabbing every spinlock in the kernel. */
  29 int stop_machine(int (*fn)(void *), void *data, const cpumask_t *cpus);
  30
  31 /**
  32  * __stop_machine: freeze the machine on all CPUs and run this function
  33  * @fn: the function to run
  34  * @data: the data ptr for the @fn
  35  * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
  36  *
  37  * Description: This is a special version of the above, which assumes cpus
  38  * won't come or go while it's being called.  Used by hotplug cpu.
  39  */
  40 int __stop_machine(int (*fn)(void *), void *data, const cpumask_t *cpus);
  41 #else
  42
  43 static inline int stop_machine(int (*fn)(void *), void *data,
  44                                const cpumask_t *cpus)
  45 {
  46         int ret;
  47         local_irq_disable();
  48         ret = fn(data);
  49         local_irq_enable();
  50         return ret;
  51 }
  52 #endif /* CONFIG_SMP */
  53
  54 static inline int __deprecated stop_machine_run(int (*fn)(void *), void *data,
  55                                                 unsigned int cpu)
  56 {
  57         /* If they don't care which cpu fn runs on, just pick one. */
  58         if (cpu == NR_CPUS)
  59                 return stop_machine(fn, data, NULL);
  60         else if (cpu == ~0U)
  61                 return stop_machine(fn, data, &cpu_possible_map);
  62         else {
  63                 cpumask_t cpus = cpumask_of_cpu(cpu);
  64                 return stop_machine(fn, data, &cpus);
  65         }
  66 }
  67 #endif /* _LINUX_STOP_MACHINE */