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 static inline void rcu_barrier_bh(void)
  35 {
  36         wait_rcu_gp(call_rcu_bh);
  37 }
  38
  39 static inline void rcu_barrier_sched(void)
  40 {
  41         wait_rcu_gp(call_rcu_sched);
  42 }
  43
  44 #ifdef CONFIG_TINY_RCU
  45
  46 static inline void synchronize_rcu_expedited(void)
  47 {
  48         synchronize_sched();    /* Only one CPU, so pretty fast anyway!!! */
  49 }
  50
  51 static inline void rcu_barrier(void)
  52 {
  53         rcu_barrier_sched();  /* Only one CPU, so only one list of callbacks! */
  54 }
  55
  56 #else /* #ifdef CONFIG_TINY_RCU */
  57
  58 void synchronize_rcu_expedited(void);
  59
  60 static inline void rcu_barrier(void)
  61 {
  62         wait_rcu_gp(call_rcu);
  63 }
  64
  65 #endif /* #else #ifdef CONFIG_TINY_RCU */
  66
  67 static inline void synchronize_rcu_bh(void)
  68 {
  69         synchronize_sched();
  70 }
  71
  72 static inline void synchronize_rcu_bh_expedited(void)
  73 {
  74         synchronize_sched();
  75 }
  76
  77 static inline void synchronize_sched_expedited(void)
  78 {
  79         synchronize_sched();
  80 }
  81
  82 static inline void kfree_call_rcu(struct rcu_head *head,
  83                                   void (*func)(struct rcu_head *rcu))
  84 {
  85         call_rcu(head, func);
  86 }
  87
  88 #ifdef CONFIG_TINY_RCU
  89
  90 static inline void rcu_preempt_note_context_switch(void)
  91 {
  92 }
  93
  94 static inline void exit_rcu(void)
  95 {
  96 }
  97
  98 static inline int rcu_needs_cpu(int cpu)
  99 {
 100         return 0;
 101 }
 102
 103 #else /* #ifdef CONFIG_TINY_RCU */
 104
 105 void rcu_preempt_note_context_switch(void);
 106 extern void exit_rcu(void);
 107 int rcu_preempt_needs_cpu(void);
 108
 109 static inline int rcu_needs_cpu(int cpu)
 110 {
 111         return rcu_preempt_needs_cpu();
 112 }
 113
 114 #endif /* #else #ifdef CONFIG_TINY_RCU */
 115
 116 static inline void rcu_note_context_switch(int cpu)
 117 {
 118         rcu_sched_qs(cpu);
 119         rcu_preempt_note_context_switch();
 120 }
 121
 122 /*
 123  * Take advantage of the fact that there is only one CPU, which
 124  * allows us to ignore virtualization-based context switches.
 125  */
 126 static inline void rcu_virt_note_context_switch(int cpu)
 127 {
 128 }
 129
 130 /*
 131  * Return the number of grace periods.
 132  */
 133 static inline long rcu_batches_completed(void)
 134 {
 135         return 0;
 136 }
 137
 138 /*
 139  * Return the number of bottom-half grace periods.
 140  */
 141 static inline long rcu_batches_completed_bh(void)
 142 {
 143         return 0;
 144 }
 145
 146 static inline void rcu_force_quiescent_state(void)
 147 {
 148 }
 149
 150 static inline void rcu_bh_force_quiescent_state(void)
 151 {
 152 }
 153
 154 static inline void rcu_sched_force_quiescent_state(void)
 155 {
 156 }
 157
 158 static inline void rcu_cpu_stall_reset(void)
 159 {
 160 }
 161
 162 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 163 extern int rcu_scheduler_active __read_mostly;
 164 extern void rcu_scheduler_starting(void);
 165 #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 166 static inline void rcu_scheduler_starting(void)
 167 {
 168 }
 169 #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 170
 171 #endif /* __LINUX_RCUTINY_H */