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