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 int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg);
  31 void stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg,
  32                          struct cpu_stop_work *work_buf);
  33 int stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);
  34 int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);
  35
  36 #else   /* CONFIG_SMP */
  37
  38 #include <linux/workqueue.h>
  39
  40 struct cpu_stop_work {
  41         struct work_struct      work;
  42         cpu_stop_fn_t           fn;
  43         void                    *arg;
  44 };
  45
  46 static inline int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg)
  47 {
  48         int ret = -ENOENT;
  49         preempt_disable();
  50         if (cpu == smp_processor_id())
  51                 ret = fn(arg);
  52         preempt_enable();
  53         return ret;
  54 }
  55
  56 static void stop_one_cpu_nowait_workfn(struct work_struct *work)
  57 {
  58         struct cpu_stop_work *stwork =
  59                 container_of(work, struct cpu_stop_work, work);
  60         preempt_disable();
  61         stwork->fn(stwork->arg);
  62         preempt_enable();
  63 }
  64
  65 static inline void stop_one_cpu_nowait(unsigned int cpu,
  66                                        cpu_stop_fn_t fn, void *arg,
  67                                        struct cpu_stop_work *work_buf)
  68 {
  69         if (cpu == smp_processor_id()) {
  70                 INIT_WORK(&work_buf->work, stop_one_cpu_nowait_workfn);
  71                 work_buf->fn = fn;
  72                 work_buf->arg = arg;
  73                 schedule_work(&work_buf->work);
  74         }
  75 }
  76
  77 static inline int stop_cpus(const struct cpumask *cpumask,
  78                             cpu_stop_fn_t fn, void *arg)
  79 {
  80         if (cpumask_test_cpu(raw_smp_processor_id(), cpumask))
  81                 return stop_one_cpu(raw_smp_processor_id(), fn, arg);
  82         return -ENOENT;
  83 }
  84
  85 static inline int try_stop_cpus(const struct cpumask *cpumask,
  86                                 cpu_stop_fn_t fn, void *arg)
  87 {
  88         return stop_cpus(cpumask, fn, arg);
  89 }
  90
  91 #endif  /* CONFIG_SMP */
  92
  93 /*
  94  * stop_machine "Bogolock": stop the entire machine, disable
  95  * interrupts.  This is a very heavy lock, which is equivalent to
  96  * grabbing every spinlock (and more).  So the "read" side to such a
  97  * lock is anything which disables preeempt.
  98  */
  99 #if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP)
 100
 101 /**
 102  * stop_machine: freeze the machine on all CPUs and run this function
 103  * @fn: the function to run
 104  * @data: the data ptr for the @fn()
 105  * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
 106  *
 107  * Description: This causes a thread to be scheduled on every cpu,
 108  * each of which disables interrupts.  The result is that noone is
 109  * holding a spinlock or inside any other preempt-disabled region when
 110  * @fn() runs.
 111  *
 112  * This can be thought of as a very heavy write lock, equivalent to
 113  * grabbing every spinlock in the kernel. */
 114 int stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
 115
 116 /**
 117  * __stop_machine: freeze the machine on all CPUs and run this function
 118  * @fn: the function to run
 119  * @data: the data ptr for the @fn
 120  * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
 121  *
 122  * Description: This is a special version of the above, which assumes cpus
 123  * won't come or go while it's being called.  Used by hotplug cpu.
 124  */
 125 int __stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
 126
 127 #else    /* CONFIG_STOP_MACHINE && CONFIG_SMP */
 128
 129 static inline int stop_machine(int (*fn)(void *), void *data,
 130                                const struct cpumask *cpus)
 131 {
 132         int ret;
 133         local_irq_disable();
 134         ret = fn(data);
 135         local_irq_enable();
 136         return ret;
 137 }
 138
 139 #endif  /* CONFIG_STOP_MACHINE && CONFIG_SMP */
 140 #endif  /* _LINUX_STOP_MACHINE */