LXR linux/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
  30static inline void rcu_init(void)
  31{
  32}
  33
  34static inline void rcu_barrier_bh(void)
  35{
  36        wait_rcu_gp(call_rcu_bh);
  37}
  38
  39static inline void rcu_barrier_sched(void)
  40{
  41        wait_rcu_gp(call_rcu_sched);
  42}
  43
  44#ifdef CONFIG_TINY_RCU
  45
  46static inline void synchronize_rcu_expedited(void)
  47{
  48        synchronize_sched();    /* Only one CPU, so pretty fast anyway!!! */
  49}
  50
  51static 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
  58void synchronize_rcu_expedited(void);
  59
  60static inline void rcu_barrier(void)
  61{
  62        wait_rcu_gp(call_rcu);
  63}
  64
  65#endif /* #else #ifdef CONFIG_TINY_RCU */
  66
  67static inline void synchronize_rcu_bh(void)
  68{
  69        synchronize_sched();
  70}
  71
  72static inline void synchronize_rcu_bh_expedited(void)
  73{
  74        synchronize_sched();
  75}
  76
  77static inline void synchronize_sched_expedited(void)
  78{
  79        synchronize_sched();
  80}
  81
  82static 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
  90static inline void rcu_preempt_note_context_switch(void)
  91{
  92}
  93
  94static 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
 102void rcu_preempt_note_context_switch(void);
 103int rcu_preempt_needs_cpu(void);
 104
 105static 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
 113static 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 */
 123static inline void rcu_virt_note_context_switch(int cpu)
 124{
 125}
 126
 127/*
 128 * Return the number of grace periods.
 129 */
 130static inline long rcu_batches_completed(void)
 131{
 132        return 0;
 133}
 134
 135/*
 136 * Return the number of bottom-half grace periods.
 137 */
 138static inline long rcu_batches_completed_bh(void)
 139{
 140        return 0;
 141}
 142
 143static inline void rcu_force_quiescent_state(void)
 144{
 145}
 146
 147static inline void rcu_bh_force_quiescent_state(void)
 148{
 149}
 150
 151static inline void rcu_sched_force_quiescent_state(void)
 152{
 153}
 154
 155static inline void rcu_cpu_stall_reset(void)
 156{
 157}
 158
 159#ifdef CONFIG_DEBUG_LOCK_ALLOC
 160extern int rcu_scheduler_active __read_mostly;
 161extern void rcu_scheduler_starting(void);
 162#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 163static inline void rcu_scheduler_starting(void)
 164{
 165}
 166#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 167
 168#endif /* __LINUX_RCUTINY_H */
 169