linux/include/linux/rcutiny.h
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   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, you can access it online at
  16 * http://www.gnu.org/licenses/gpl-2.0.html.
  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
  30struct rcu_dynticks;
  31static inline int rcu_dynticks_snap(struct rcu_dynticks *rdtp)
  32{
  33        return 0;
  34}
  35
  36static inline unsigned long get_state_synchronize_rcu(void)
  37{
  38        return 0;
  39}
  40
  41static inline void cond_synchronize_rcu(unsigned long oldstate)
  42{
  43        might_sleep();
  44}
  45
  46static inline unsigned long get_state_synchronize_sched(void)
  47{
  48        return 0;
  49}
  50
  51static inline void cond_synchronize_sched(unsigned long oldstate)
  52{
  53        might_sleep();
  54}
  55
  56extern void rcu_barrier_bh(void);
  57extern void rcu_barrier_sched(void);
  58
  59static inline void synchronize_rcu_expedited(void)
  60{
  61        synchronize_sched();    /* Only one CPU, so pretty fast anyway!!! */
  62}
  63
  64static inline void rcu_barrier(void)
  65{
  66        rcu_barrier_sched();  /* Only one CPU, so only one list of callbacks! */
  67}
  68
  69static inline void synchronize_rcu_bh(void)
  70{
  71        synchronize_sched();
  72}
  73
  74static inline void synchronize_rcu_bh_expedited(void)
  75{
  76        synchronize_sched();
  77}
  78
  79static inline void synchronize_sched_expedited(void)
  80{
  81        synchronize_sched();
  82}
  83
  84static inline void kfree_call_rcu(struct rcu_head *head,
  85                                  rcu_callback_t func)
  86{
  87        call_rcu(head, func);
  88}
  89
  90static inline void rcu_note_context_switch(void)
  91{
  92        rcu_sched_qs();
  93}
  94
  95/*
  96 * Take advantage of the fact that there is only one CPU, which
  97 * allows us to ignore virtualization-based context switches.
  98 */
  99static inline void rcu_virt_note_context_switch(int cpu)
 100{
 101}
 102
 103/*
 104 * Return the number of grace periods started.
 105 */
 106static inline unsigned long rcu_batches_started(void)
 107{
 108        return 0;
 109}
 110
 111/*
 112 * Return the number of bottom-half grace periods started.
 113 */
 114static inline unsigned long rcu_batches_started_bh(void)
 115{
 116        return 0;
 117}
 118
 119/*
 120 * Return the number of sched grace periods started.
 121 */
 122static inline unsigned long rcu_batches_started_sched(void)
 123{
 124        return 0;
 125}
 126
 127/*
 128 * Return the number of grace periods completed.
 129 */
 130static inline unsigned long rcu_batches_completed(void)
 131{
 132        return 0;
 133}
 134
 135/*
 136 * Return the number of bottom-half grace periods completed.
 137 */
 138static inline unsigned long rcu_batches_completed_bh(void)
 139{
 140        return 0;
 141}
 142
 143/*
 144 * Return the number of sched grace periods completed.
 145 */
 146static inline unsigned long rcu_batches_completed_sched(void)
 147{
 148        return 0;
 149}
 150
 151/*
 152 * Return the number of expedited grace periods completed.
 153 */
 154static inline unsigned long rcu_exp_batches_completed(void)
 155{
 156        return 0;
 157}
 158
 159/*
 160 * Return the number of expedited sched grace periods completed.
 161 */
 162static inline unsigned long rcu_exp_batches_completed_sched(void)
 163{
 164        return 0;
 165}
 166
 167static inline void rcu_force_quiescent_state(void)
 168{
 169}
 170
 171static inline void rcu_bh_force_quiescent_state(void)
 172{
 173}
 174
 175static inline void rcu_sched_force_quiescent_state(void)
 176{
 177}
 178
 179static inline void show_rcu_gp_kthreads(void)
 180{
 181}
 182
 183static inline void rcu_cpu_stall_reset(void)
 184{
 185}
 186
 187static inline void rcu_idle_enter(void)
 188{
 189}
 190
 191static inline void rcu_idle_exit(void)
 192{
 193}
 194
 195static inline void rcu_irq_enter(void)
 196{
 197}
 198
 199static inline void rcu_irq_exit_irqson(void)
 200{
 201}
 202
 203static inline void rcu_irq_enter_irqson(void)
 204{
 205}
 206
 207static inline void rcu_irq_exit(void)
 208{
 209}
 210
 211static inline void exit_rcu(void)
 212{
 213}
 214
 215#ifdef CONFIG_DEBUG_LOCK_ALLOC
 216extern int rcu_scheduler_active __read_mostly;
 217void rcu_scheduler_starting(void);
 218#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 219static inline void rcu_scheduler_starting(void)
 220{
 221}
 222#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 223
 224#if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_RCU_TRACE)
 225
 226static inline bool rcu_is_watching(void)
 227{
 228        return __rcu_is_watching();
 229}
 230
 231#else /* defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_RCU_TRACE) */
 232
 233static inline bool rcu_is_watching(void)
 234{
 235        return true;
 236}
 237
 238#endif /* #else defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_RCU_TRACE) */
 239
 240static inline void rcu_all_qs(void)
 241{
 242        barrier(); /* Avoid RCU read-side critical sections leaking across. */
 243}
 244
 245/* RCUtree hotplug events */
 246#define rcutree_prepare_cpu      NULL
 247#define rcutree_online_cpu       NULL
 248#define rcutree_offline_cpu      NULL
 249#define rcutree_dead_cpu         NULL
 250#define rcutree_dying_cpu        NULL
 251
 252#endif /* __LINUX_RCUTINY_H */
 253