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