include/linux/rcutree.h

   1 /*
   2  * Read-Copy Update mechanism for mutual exclusion (tree-based version)
   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: Dipankar Sarma <dipankar@in.ibm.com>
  21  *         Paul E. McKenney <paulmck@linux.vnet.ibm.com> Hierarchical algorithm
  22  *
  23  * Based on the original work by Paul McKenney <paulmck@us.ibm.com>
  24  * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
  25  *
  26  * For detailed explanation of Read-Copy Update mechanism see -
  27  *      Documentation/RCU
  28  */
  29
  30 #ifndef __LINUX_RCUTREE_H
  31 #define __LINUX_RCUTREE_H
  32
  33 extern void rcu_sched_qs(int cpu);
  34 extern void rcu_bh_qs(int cpu);
  35
  36 extern int rcu_needs_cpu(int cpu);
  37
  38 #ifdef CONFIG_TREE_PREEMPT_RCU
  39
  40 extern void __rcu_read_lock(void);
  41 extern void __rcu_read_unlock(void);
  42 extern void exit_rcu(void);
  43
  44 #else /* #ifdef CONFIG_TREE_PREEMPT_RCU */
  45
  46 static inline void __rcu_read_lock(void)
  47 {
  48         preempt_disable();
  49 }
  50
  51 static inline void __rcu_read_unlock(void)
  52 {
  53         preempt_enable();
  54 }
  55
  56 #define __synchronize_sched() synchronize_rcu()
  57
  58 static inline void exit_rcu(void)
  59 {
  60 }
  61
  62 #endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */
  63
  64 static inline void __rcu_read_lock_bh(void)
  65 {
  66         local_bh_disable();
  67 }
  68 static inline void __rcu_read_unlock_bh(void)
  69 {
  70         local_bh_enable();
  71 }
  72
  73 extern void call_rcu_sched(struct rcu_head *head,
  74                            void (*func)(struct rcu_head *rcu));
  75
  76 static inline void synchronize_rcu_expedited(void)
  77 {
  78         synchronize_sched_expedited();
  79 }
  80
  81 static inline void synchronize_rcu_bh_expedited(void)
  82 {
  83         synchronize_sched_expedited();
  84 }
  85
  86 extern void __rcu_init(void);
  87 extern void rcu_check_callbacks(int cpu, int user);
  88 extern void rcu_restart_cpu(int cpu);
  89
  90 extern long rcu_batches_completed(void);
  91 extern long rcu_batches_completed_bh(void);
  92 extern long rcu_batches_completed_sched(void);
  93
  94 static inline void rcu_init_sched(void)
  95 {
  96 }
  97
  98 #ifdef CONFIG_NO_HZ
  99 void rcu_enter_nohz(void);
 100 void rcu_exit_nohz(void);
 101 #else /* CONFIG_NO_HZ */
 102 static inline void rcu_enter_nohz(void)
 103 {
 104 }
 105 static inline void rcu_exit_nohz(void)
 106 {
 107 }
 108 #endif /* CONFIG_NO_HZ */
 109
 110 /* A context switch is a grace period for rcutree. */
 111 static inline int rcu_blocking_is_gp(void)
 112 {
 113         return num_online_cpus() == 1;
 114 }
 115
 116 #endif /* __LINUX_RCUTREE_H */