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 #ifdef CONFIG_RCU_BOOST
  31 static inline void rcu_init(void)
  32 {
  33 }
  34 #else /* #ifdef CONFIG_RCU_BOOST */
  35 void rcu_init(void);
  36 #endif /* #else #ifdef CONFIG_RCU_BOOST */
  37
  38 static inline void rcu_barrier_bh(void)
  39 {
  40         wait_rcu_gp(call_rcu_bh);
  41 }
  42
  43 static inline void rcu_barrier_sched(void)
  44 {
  45         wait_rcu_gp(call_rcu_sched);
  46 }
  47
  48 #ifdef CONFIG_TINY_RCU
  49
  50 static inline void synchronize_rcu_expedited(void)
  51 {
  52         synchronize_sched();    /* Only one CPU, so pretty fast anyway!!! */
  53 }
  54
  55 static inline void rcu_barrier(void)
  56 {
  57         rcu_barrier_sched();  /* Only one CPU, so only one list of callbacks! */
  58 }
  59
  60 #else /* #ifdef CONFIG_TINY_RCU */
  61
  62 void synchronize_rcu_expedited(void);
  63
  64 static inline void rcu_barrier(void)
  65 {
  66         wait_rcu_gp(call_rcu);
  67 }
  68
  69 #endif /* #else #ifdef CONFIG_TINY_RCU */
  70
  71 static inline void synchronize_rcu_bh(void)
  72 {
  73         synchronize_sched();
  74 }
  75
  76 static inline void synchronize_rcu_bh_expedited(void)
  77 {
  78         synchronize_sched();
  79 }
  80
  81 static inline void synchronize_sched_expedited(void)
  82 {
  83         synchronize_sched();
  84 }
  85
  86 #ifdef CONFIG_TINY_RCU
  87
  88 static inline void rcu_preempt_note_context_switch(void)
  89 {
  90 }
  91
  92 static inline void exit_rcu(void)
  93 {
  94 }
  95
  96 static inline int rcu_needs_cpu(int cpu)
  97 {
  98         return 0;
  99 }
 100
 101 #else /* #ifdef CONFIG_TINY_RCU */
 102
 103 void rcu_preempt_note_context_switch(void);
 104 extern void exit_rcu(void);
 105 int rcu_preempt_needs_cpu(void);
 106
 107 static inline int rcu_needs_cpu(int cpu)
 108 {
 109         return rcu_preempt_needs_cpu();
 110 }
 111
 112 #endif /* #else #ifdef CONFIG_TINY_RCU */
 113
 114 static inline void rcu_note_context_switch(int cpu)
 115 {
 116         rcu_sched_qs(cpu);
 117         rcu_preempt_note_context_switch();
 118 }
 119
 120 /*
 121  * Take advantage of the fact that there is only one CPU, which
 122  * allows us to ignore virtualization-based context switches.
 123  */
 124 static inline void rcu_virt_note_context_switch(int cpu)
 125 {
 126 }
 127
 128 /*
 129  * Return the number of grace periods.
 130  */
 131 static inline long rcu_batches_completed(void)
 132 {
 133         return 0;
 134 }
 135
 136 /*
 137  * Return the number of bottom-half grace periods.
 138  */
 139 static inline long rcu_batches_completed_bh(void)
 140 {
 141         return 0;
 142 }
 143
 144 static inline void rcu_force_quiescent_state(void)
 145 {
 146 }
 147
 148 static inline void rcu_bh_force_quiescent_state(void)
 149 {
 150 }
 151
 152 static inline void rcu_sched_force_quiescent_state(void)
 153 {
 154 }
 155
 156 static inline void rcu_cpu_stall_reset(void)
 157 {
 158 }
 159
 160 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 161 extern int rcu_scheduler_active __read_mostly;
 162 extern void rcu_scheduler_starting(void);
 163 #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 164 static inline void rcu_scheduler_starting(void)
 165 {
 166 }
 167 #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 168
 169 #endif /* __LINUX_RCUTINY_H */