LXR linux/include/linux/preempt.h

   1#ifndef __LINUX_PREEMPT_H
   2#define __LINUX_PREEMPT_H
   3
   4/*
   5 * include/linux/preempt.h - macros for accessing and manipulating
   6 * preempt_count (used for kernel preemption, interrupt count, etc.)
   7 */
   8
   9#include <linux/thread_info.h>
  10#include <linux/linkage.h>
  11#include <linux/list.h>
  12
  13#if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_PREEMPT_TRACER)
  14  extern void add_preempt_count(int val);
  15  extern void sub_preempt_count(int val);
  16#else
  17# define add_preempt_count(val) do { preempt_count() += (val); } while (0)
  18# define sub_preempt_count(val) do { preempt_count() -= (val); } while (0)
  19#endif
  20
  21#define inc_preempt_count() add_preempt_count(1)
  22#define dec_preempt_count() sub_preempt_count(1)
  23
  24#define preempt_count() (current_thread_info()->preempt_count)
  25
  26#ifdef CONFIG_PREEMPT
  27
  28asmlinkage void preempt_schedule(void);
  29
  30#define preempt_disable() \
  31do { \
  32        inc_preempt_count(); \
  33        barrier(); \
  34} while (0)
  35
  36#define preempt_enable_no_resched() \
  37do { \
  38        barrier(); \
  39        dec_preempt_count(); \
  40} while (0)
  41
  42#define preempt_check_resched() \
  43do { \
  44        if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) \
  45                preempt_schedule(); \
  46} while (0)
  47
  48#define preempt_enable() \
  49do { \
  50        preempt_enable_no_resched(); \
  51        barrier(); \
  52        preempt_check_resched(); \
  53} while (0)
  54
  55/* For debugging and tracer internals only! */
  56#define add_preempt_count_notrace(val)                  \
  57        do { preempt_count() += (val); } while (0)
  58#define sub_preempt_count_notrace(val)                  \
  59        do { preempt_count() -= (val); } while (0)
  60#define inc_preempt_count_notrace() add_preempt_count_notrace(1)
  61#define dec_preempt_count_notrace() sub_preempt_count_notrace(1)
  62
  63#define preempt_disable_notrace() \
  64do { \
  65        inc_preempt_count_notrace(); \
  66        barrier(); \
  67} while (0)
  68
  69#define preempt_enable_no_resched_notrace() \
  70do { \
  71        barrier(); \
  72        dec_preempt_count_notrace(); \
  73} while (0)
  74
  75/* preempt_check_resched is OK to trace */
  76#define preempt_enable_notrace() \
  77do { \
  78        preempt_enable_no_resched_notrace(); \
  79        barrier(); \
  80        preempt_check_resched(); \
  81} while (0)
  82
  83#else
  84
  85#define preempt_disable()               do { } while (0)
  86#define preempt_enable_no_resched()     do { } while (0)
  87#define preempt_enable()                do { } while (0)
  88#define preempt_check_resched()         do { } while (0)
  89
  90#define preempt_disable_notrace()               do { } while (0)
  91#define preempt_enable_no_resched_notrace()     do { } while (0)
  92#define preempt_enable_notrace()                do { } while (0)
  93
  94#endif
  95
  96#ifdef CONFIG_PREEMPT_NOTIFIERS
  97
  98struct preempt_notifier;
  99
 100/**
 101 * preempt_ops - notifiers called when a task is preempted and rescheduled
 102 * @sched_in: we're about to be rescheduled:
 103 *    notifier: struct preempt_notifier for the task being scheduled
 104 *    cpu:  cpu we're scheduled on
 105 * @sched_out: we've just been preempted
 106 *    notifier: struct preempt_notifier for the task being preempted
 107 *    next: the task that's kicking us out
 108 */
 109struct preempt_ops {
 110        void (*sched_in)(struct preempt_notifier *notifier, int cpu);
 111        void (*sched_out)(struct preempt_notifier *notifier,
 112                          struct task_struct *next);
 113};
 114
 115/**
 116 * preempt_notifier - key for installing preemption notifiers
 117 * @link: internal use
 118 * @ops: defines the notifier functions to be called
 119 *
 120 * Usually used in conjunction with container_of().
 121 */
 122struct preempt_notifier {
 123        struct hlist_node link;
 124        struct preempt_ops *ops;
 125};
 126
 127void preempt_notifier_register(struct preempt_notifier *notifier);
 128void preempt_notifier_unregister(struct preempt_notifier *notifier);
 129
 130static inline void preempt_notifier_init(struct preempt_notifier *notifier,
 131                                     struct preempt_ops *ops)
 132{
 133        INIT_HLIST_NODE(&notifier->link);
 134        notifier->ops = ops;
 135}
 136
 137#endif
 138
 139#endif /* __LINUX_PREEMPT_H */
 140