include/linux/rcutiny.h

   1 /*
   2  * Read-Copy Update mechanism for mutual exclusion, the Bloatwatch edition.
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  17  *
  18  * Copyright IBM Corporation, 2008
  19  *
  20  * Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
  21  *
  22  * For detailed explanation of Read-Copy Update mechanism see -
  23  *              Documentation/RCU
  24  */
  25 #ifndef __LINUX_TINY_H
  26 #define __LINUX_TINY_H
  27
  28 #include <linux/cache.h>
  29
  30 void rcu_sched_qs(int cpu);
  31 void rcu_bh_qs(int cpu);
  32
  33 #ifdef CONFIG_TINY_RCU
  34 #define __rcu_read_lock()       preempt_disable()
  35 #define __rcu_read_unlock()     preempt_enable()
  36 #else /* #ifdef CONFIG_TINY_RCU */
  37 void __rcu_read_lock(void);
  38 void __rcu_read_unlock(void);
  39 #endif /* #else #ifdef CONFIG_TINY_RCU */
  40 #define __rcu_read_lock_bh()    local_bh_disable()
  41 #define __rcu_read_unlock_bh()  local_bh_enable()
  42 extern void call_rcu_sched(struct rcu_head *head,
  43                            void (*func)(struct rcu_head *rcu));
  44
  45 #define rcu_init_sched()        do { } while (0)
  46
  47 extern void synchronize_sched(void);
  48
  49 #ifdef CONFIG_TINY_RCU
  50
  51 #define call_rcu                call_rcu_sched
  52
  53 static inline void synchronize_rcu(void)
  54 {
  55         synchronize_sched();
  56 }
  57
  58 static inline void synchronize_rcu_expedited(void)
  59 {
  60         synchronize_sched();    /* Only one CPU, so pretty fast anyway!!! */
  61 }
  62
  63 static inline void rcu_barrier(void)
  64 {
  65         rcu_barrier_sched();  /* Only one CPU, so only one list of callbacks! */
  66 }
  67
  68 #else /* #ifdef CONFIG_TINY_RCU */
  69
  70 void synchronize_rcu(void);
  71 void rcu_barrier(void);
  72 void synchronize_rcu_expedited(void);
  73
  74 #endif /* #else #ifdef CONFIG_TINY_RCU */
  75
  76 static inline void synchronize_rcu_bh(void)
  77 {
  78         synchronize_sched();
  79 }
  80
  81 static inline void synchronize_rcu_bh_expedited(void)
  82 {
  83         synchronize_sched();
  84 }
  85
  86 struct notifier_block;
  87
  88 #ifdef CONFIG_NO_HZ
  89
  90 extern void rcu_enter_nohz(void);
  91 extern void rcu_exit_nohz(void);
  92
  93 #else /* #ifdef CONFIG_NO_HZ */
  94
  95 static inline void rcu_enter_nohz(void)
  96 {
  97 }
  98
  99 static inline void rcu_exit_nohz(void)
 100 {
 101 }
 102
 103 #endif /* #else #ifdef CONFIG_NO_HZ */
 104
 105 #ifdef CONFIG_TINY_RCU
 106
 107 static inline void rcu_preempt_note_context_switch(void)
 108 {
 109 }
 110
 111 static inline void exit_rcu(void)
 112 {
 113 }
 114
 115 static inline int rcu_needs_cpu(int cpu)
 116 {
 117         return 0;
 118 }
 119
 120 static inline int rcu_preempt_depth(void)
 121 {
 122         return 0;
 123 }
 124
 125 #else /* #ifdef CONFIG_TINY_RCU */
 126
 127 void rcu_preempt_note_context_switch(void);
 128 extern void exit_rcu(void);
 129 int rcu_preempt_needs_cpu(void);
 130
 131 static inline int rcu_needs_cpu(int cpu)
 132 {
 133         return rcu_preempt_needs_cpu();
 134 }
 135
 136 #endif /* #else #ifdef CONFIG_TINY_RCU */
 137
 138 static inline void rcu_note_context_switch(int cpu)
 139 {
 140         rcu_sched_qs(cpu);
 141         rcu_preempt_note_context_switch();
 142 }
 143
 144 extern void rcu_check_callbacks(int cpu, int user);
 145
 146 /*
 147  * Return the number of grace periods.
 148  */
 149 static inline long rcu_batches_completed(void)
 150 {
 151         return 0;
 152 }
 153
 154 /*
 155  * Return the number of bottom-half grace periods.
 156  */
 157 static inline long rcu_batches_completed_bh(void)
 158 {
 159         return 0;
 160 }
 161
 162 static inline void rcu_force_quiescent_state(void)
 163 {
 164 }
 165
 166 static inline void rcu_bh_force_quiescent_state(void)
 167 {
 168 }
 169
 170 static inline void rcu_sched_force_quiescent_state(void)
 171 {
 172 }
 173
 174 static inline void rcu_cpu_stall_reset(void)
 175 {
 176 }
 177
 178 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 179
 180 extern int rcu_scheduler_active __read_mostly;
 181 extern void rcu_scheduler_starting(void);
 182
 183 #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 184
 185 static inline void rcu_scheduler_starting(void)
 186 {
 187 }
 188
 189 #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 190
 191 #endif /* __LINUX_RCUTINY_H */