include/linux/stop_machine.h

   1 #ifndef _LINUX_STOP_MACHINE
   2 #define _LINUX_STOP_MACHINE
   3
   4 #include <linux/cpu.h>
   5 #include <linux/cpumask.h>
   6 #include <linux/list.h>
   7 #include <asm/system.h>
   8
   9 /*
  10  * stop_cpu[s]() is simplistic per-cpu maximum priority cpu
  11  * monopolization mechanism.  The caller can specify a non-sleeping
  12  * function to be executed on a single or multiple cpus preempting all
  13  * other processes and monopolizing those cpus until it finishes.
  14  *
  15  * Resources for this mechanism are preallocated when a cpu is brought
  16  * up and requests are guaranteed to be served as long as the target
  17  * cpus are online.
  18  */
  19 typedef int (*cpu_stop_fn_t)(void *arg);
  20
  21 #ifdef CONFIG_SMP
  22
  23 struct cpu_stop_work {
  24         struct list_head        list;           /* cpu_stopper->works */
  25         cpu_stop_fn_t           fn;
  26         void                    *arg;
  27         struct cpu_stop_done    *done;
  28 };
  29
  30 extern struct mutex stop_cpus_mutex;
  31
  32 int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg);
  33 void stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg,
  34                          struct cpu_stop_work *work_buf);
  35 int stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);
  36 int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);
  37
  38 #else   /* CONFIG_SMP */
  39
  40 #include <linux/workqueue.h>
  41
  42 struct cpu_stop_work {
  43         struct work_struct      work;
  44         cpu_stop_fn_t           fn;
  45         void                    *arg;
  46 };
  47
  48 static inline int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg)
  49 {
  50         int ret = -ENOENT;
  51         preempt_disable();
  52         if (cpu == smp_processor_id())
  53                 ret = fn(arg);
  54         preempt_enable();
  55         return ret;
  56 }
  57
  58 static void stop_one_cpu_nowait_workfn(struct work_struct *work)
  59 {
  60         struct cpu_stop_work *stwork =
  61                 container_of(work, struct cpu_stop_work, work);
  62         preempt_disable();
  63         stwork->fn(stwork->arg);
  64         preempt_enable();
  65 }
  66
  67 static inline void stop_one_cpu_nowait(unsigned int cpu,
  68                                        cpu_stop_fn_t fn, void *arg,
  69                                        struct cpu_stop_work *work_buf)
  70 {
  71         if (cpu == smp_processor_id()) {
  72                 INIT_WORK(&work_buf->work, stop_one_cpu_nowait_workfn);
  73                 work_buf->fn = fn;
  74                 work_buf->arg = arg;
  75                 schedule_work(&work_buf->work);
  76         }
  77 }
  78
  79 static inline int stop_cpus(const struct cpumask *cpumask,
  80                             cpu_stop_fn_t fn, void *arg)
  81 {
  82         if (cpumask_test_cpu(raw_smp_processor_id(), cpumask))
  83                 return stop_one_cpu(raw_smp_processor_id(), fn, arg);
  84         return -ENOENT;
  85 }
  86
  87 static inline int try_stop_cpus(const struct cpumask *cpumask,
  88                                 cpu_stop_fn_t fn, void *arg)
  89 {
  90         return stop_cpus(cpumask, fn, arg);
  91 }
  92
  93 #endif  /* CONFIG_SMP */
  94
  95 /*
  96  * stop_machine "Bogolock": stop the entire machine, disable
  97  * interrupts.  This is a very heavy lock, which is equivalent to
  98  * grabbing every spinlock (and more).  So the "read" side to such a
  99  * lock is anything which disables preeempt.
 100  */
 101 #if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP)
 102
 103 /**
 104  * stop_machine: freeze the machine on all CPUs and run this function
 105  * @fn: the function to run
 106  * @data: the data ptr for the @fn()
 107  * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
 108  *
 109  * Description: This causes a thread to be scheduled on every cpu,
 110  * each of which disables interrupts.  The result is that no one is
 111  * holding a spinlock or inside any other preempt-disabled region when
 112  * @fn() runs.
 113  *
 114  * This can be thought of as a very heavy write lock, equivalent to
 115  * grabbing every spinlock in the kernel. */
 116 int stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
 117
 118 /**
 119  * __stop_machine: freeze the machine on all CPUs and run this function
 120  * @fn: the function to run
 121  * @data: the data ptr for the @fn
 122  * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
 123  *
 124  * Description: This is a special version of the above, which assumes cpus
 125  * won't come or go while it's being called.  Used by hotplug cpu.
 126  */
 127 int __stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
 128
 129 #else    /* CONFIG_STOP_MACHINE && CONFIG_SMP */
 130
 131 static inline int __stop_machine(int (*fn)(void *), void *data,
 132                                  const struct cpumask *cpus)
 133 {
 134         int ret;
 135         local_irq_disable();
 136         ret = fn(data);
 137         local_irq_enable();
 138         return ret;
 139 }
 140
 141 static inline int stop_machine(int (*fn)(void *), void *data,
 142                                const struct cpumask *cpus)
 143 {
 144         return __stop_machine(fn, data, cpus);
 145 }
 146
 147 #endif  /* CONFIG_STOP_MACHINE && CONFIG_SMP */
 148 #endif  /* _LINUX_STOP_MACHINE */