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, 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
  30 struct rcu_dynticks;
  31 static inline int rcu_dynticks_snap(struct rcu_dynticks *rdtp)
  32 {
  33         return 0;
  34 }
  35
  36 static inline bool rcu_eqs_special_set(int cpu)
  37 {
  38         return false;  /* Never flag non-existent other CPUs! */
  39 }
  40
  41 static inline unsigned long get_state_synchronize_rcu(void)
  42 {
  43         return 0;
  44 }
  45
  46 static inline void cond_synchronize_rcu(unsigned long oldstate)
  47 {
  48         might_sleep();
  49 }
  50
  51 static inline unsigned long get_state_synchronize_sched(void)
  52 {
  53         return 0;
  54 }
  55
  56 static inline void cond_synchronize_sched(unsigned long oldstate)
  57 {
  58         might_sleep();
  59 }
  60
  61 extern void rcu_barrier_bh(void);
  62 extern void rcu_barrier_sched(void);
  63
  64 static inline void synchronize_rcu_expedited(void)
  65 {
  66         synchronize_sched();    /* Only one CPU, so pretty fast anyway!!! */
  67 }
  68
  69 static inline void rcu_barrier(void)
  70 {
  71         rcu_barrier_sched();  /* Only one CPU, so only one list of callbacks! */
  72 }
  73
  74 static inline void synchronize_rcu_bh(void)
  75 {
  76         synchronize_sched();
  77 }
  78
  79 static inline void synchronize_rcu_bh_expedited(void)
  80 {
  81         synchronize_sched();
  82 }
  83
  84 static inline void synchronize_sched_expedited(void)
  85 {
  86         synchronize_sched();
  87 }
  88
  89 static inline void kfree_call_rcu(struct rcu_head *head,
  90                                   rcu_callback_t func)
  91 {
  92         call_rcu(head, func);
  93 }
  94
  95 #define rcu_note_context_switch(preempt) \
  96         do { \
  97                 rcu_sched_qs(); \
  98                 rcu_note_voluntary_context_switch_lite(current); \
  99         } while (0)
 100
 101 /*
 102  * Take advantage of the fact that there is only one CPU, which
 103  * allows us to ignore virtualization-based context switches.
 104  */
 105 static inline void rcu_virt_note_context_switch(int cpu)
 106 {
 107 }
 108
 109 /*
 110  * Return the number of grace periods started.
 111  */
 112 static inline unsigned long rcu_batches_started(void)
 113 {
 114         return 0;
 115 }
 116
 117 /*
 118  * Return the number of bottom-half grace periods started.
 119  */
 120 static inline unsigned long rcu_batches_started_bh(void)
 121 {
 122         return 0;
 123 }
 124
 125 /*
 126  * Return the number of sched grace periods started.
 127  */
 128 static inline unsigned long rcu_batches_started_sched(void)
 129 {
 130         return 0;
 131 }
 132
 133 /*
 134  * Return the number of grace periods completed.
 135  */
 136 static inline unsigned long rcu_batches_completed(void)
 137 {
 138         return 0;
 139 }
 140
 141 /*
 142  * Return the number of bottom-half grace periods completed.
 143  */
 144 static inline unsigned long rcu_batches_completed_bh(void)
 145 {
 146         return 0;
 147 }
 148
 149 /*
 150  * Return the number of sched grace periods completed.
 151  */
 152 static inline unsigned long rcu_batches_completed_sched(void)
 153 {
 154         return 0;
 155 }
 156
 157 /*
 158  * Return the number of expedited grace periods completed.
 159  */
 160 static inline unsigned long rcu_exp_batches_completed(void)
 161 {
 162         return 0;
 163 }
 164
 165 /*
 166  * Return the number of expedited sched grace periods completed.
 167  */
 168 static inline unsigned long rcu_exp_batches_completed_sched(void)
 169 {
 170         return 0;
 171 }
 172
 173 static inline void rcu_force_quiescent_state(void)
 174 {
 175 }
 176
 177 static inline void rcu_bh_force_quiescent_state(void)
 178 {
 179 }
 180
 181 static inline void rcu_sched_force_quiescent_state(void)
 182 {
 183 }
 184
 185 static inline void show_rcu_gp_kthreads(void)
 186 {
 187 }
 188
 189 static inline void rcu_cpu_stall_reset(void)
 190 {
 191 }
 192
 193 static inline void rcu_idle_enter(void)
 194 {
 195 }
 196
 197 static inline void rcu_idle_exit(void)
 198 {
 199 }
 200
 201 static inline void rcu_irq_enter(void)
 202 {
 203 }
 204
 205 static inline void rcu_irq_exit_irqson(void)
 206 {
 207 }
 208
 209 static inline void rcu_irq_enter_irqson(void)
 210 {
 211 }
 212
 213 static inline void rcu_irq_exit(void)
 214 {
 215 }
 216
 217 static inline void exit_rcu(void)
 218 {
 219 }
 220
 221 #if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_SRCU)
 222 extern int rcu_scheduler_active __read_mostly;
 223 void rcu_scheduler_starting(void);
 224 #else /* #if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_SRCU) */
 225 static inline void rcu_scheduler_starting(void)
 226 {
 227 }
 228 #endif /* #else #if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_SRCU) */
 229
 230 #if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_RCU_TRACE)
 231
 232 static inline bool rcu_is_watching(void)
 233 {
 234         return __rcu_is_watching();
 235 }
 236
 237 #else /* defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_RCU_TRACE) */
 238
 239 static inline bool rcu_is_watching(void)
 240 {
 241         return true;
 242 }
 243
 244 #endif /* #else defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_RCU_TRACE) */
 245
 246 static inline void rcu_request_urgent_qs_task(struct task_struct *t)
 247 {
 248 }
 249
 250 static inline void rcu_all_qs(void)
 251 {
 252         barrier(); /* Avoid RCU read-side critical sections leaking across. */
 253 }
 254
 255 /* RCUtree hotplug events */
 256 #define rcutree_prepare_cpu      NULL
 257 #define rcutree_online_cpu       NULL
 258 #define rcutree_offline_cpu      NULL
 259 #define rcutree_dead_cpu         NULL
 260 #define rcutree_dying_cpu        NULL
 261
 262 #endif /* __LINUX_RCUTINY_H */