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