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 static inline void kfree_call_rcu(struct rcu_head *head,
  87                                   void (*func)(struct rcu_head *rcu))
  88 {
  89         call_rcu(head, func);
  90 }
  91
  92 #ifdef CONFIG_TINY_RCU
  93
  94 static inline void rcu_preempt_note_context_switch(void)
  95 {
  96 }
  97
  98 static inline void exit_rcu(void)
  99 {
 100 }
 101
 102 static inline int rcu_needs_cpu(int cpu)
 103 {
 104         return 0;
 105 }
 106
 107 #else /* #ifdef CONFIG_TINY_RCU */
 108
 109 void rcu_preempt_note_context_switch(void);
 110 extern void exit_rcu(void);
 111 int rcu_preempt_needs_cpu(void);
 112
 113 static inline int rcu_needs_cpu(int cpu)
 114 {
 115         return rcu_preempt_needs_cpu();
 116 }
 117
 118 #endif /* #else #ifdef CONFIG_TINY_RCU */
 119
 120 static inline void rcu_note_context_switch(int cpu)
 121 {
 122         rcu_sched_qs(cpu);
 123         rcu_preempt_note_context_switch();
 124 }
 125
 126 /*
 127  * Take advantage of the fact that there is only one CPU, which
 128  * allows us to ignore virtualization-based context switches.
 129  */
 130 static inline void rcu_virt_note_context_switch(int cpu)
 131 {
 132 }
 133
 134 /*
 135  * Return the number of grace periods.
 136  */
 137 static inline long rcu_batches_completed(void)
 138 {
 139         return 0;
 140 }
 141
 142 /*
 143  * Return the number of bottom-half grace periods.
 144  */
 145 static inline long rcu_batches_completed_bh(void)
 146 {
 147         return 0;
 148 }
 149
 150 static inline void rcu_force_quiescent_state(void)
 151 {
 152 }
 153
 154 static inline void rcu_bh_force_quiescent_state(void)
 155 {
 156 }
 157
 158 static inline void rcu_sched_force_quiescent_state(void)
 159 {
 160 }
 161
 162 static inline void rcu_cpu_stall_reset(void)
 163 {
 164 }
 165
 166 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 167 extern int rcu_scheduler_active __read_mostly;
 168 extern void rcu_scheduler_starting(void);
 169 #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 170 static inline void rcu_scheduler_starting(void)
 171 {
 172 }
 173 #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 174
 175 #endif /* __LINUX_RCUTINY_H */