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 struct notifier_block;
  34
  35 extern void rcu_sched_qs(int cpu);
  36 extern void rcu_bh_qs(int cpu);
  37 extern int rcu_needs_cpu(int cpu);
  38 extern void rcu_scheduler_starting(void);
  39 extern int rcu_expedited_torture_stats(char *page);
  40
  41 #ifdef CONFIG_TREE_PREEMPT_RCU
  42
  43 extern void __rcu_read_lock(void);
  44 extern void __rcu_read_unlock(void);
  45 extern void synchronize_rcu(void);
  46 extern void exit_rcu(void);
  47
  48 /*
  49  * Defined as macro as it is a very low level header
  50  * included from areas that don't even know about current
  51  */
  52 #define rcu_preempt_depth() (current->rcu_read_lock_nesting)
  53
  54 #else /* #ifdef CONFIG_TREE_PREEMPT_RCU */
  55
  56 static inline void __rcu_read_lock(void)
  57 {
  58         preempt_disable();
  59 }
  60
  61 static inline void __rcu_read_unlock(void)
  62 {
  63         preempt_enable();
  64 }
  65
  66 #define synchronize_rcu synchronize_sched
  67
  68 static inline void exit_rcu(void)
  69 {
  70 }
  71
  72 static inline int rcu_preempt_depth(void)
  73 {
  74         return 0;
  75 }
  76
  77 #endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */
  78
  79 static inline void __rcu_read_lock_bh(void)
  80 {
  81         local_bh_disable();
  82 }
  83 static inline void __rcu_read_unlock_bh(void)
  84 {
  85         local_bh_enable();
  86 }
  87
  88 extern void call_rcu_sched(struct rcu_head *head,
  89                            void (*func)(struct rcu_head *rcu));
  90 extern void synchronize_rcu_expedited(void);
  91
  92 static inline void synchronize_rcu_bh_expedited(void)
  93 {
  94         synchronize_sched_expedited();
  95 }
  96
  97 extern void rcu_check_callbacks(int cpu, int user);
  98
  99 extern long rcu_batches_completed(void);
 100 extern long rcu_batches_completed_bh(void);
 101 extern long rcu_batches_completed_sched(void);
 102
 103 #ifdef CONFIG_NO_HZ
 104 void rcu_enter_nohz(void);
 105 void rcu_exit_nohz(void);
 106 #else /* CONFIG_NO_HZ */
 107 static inline void rcu_enter_nohz(void)
 108 {
 109 }
 110 static inline void rcu_exit_nohz(void)
 111 {
 112 }
 113 #endif /* CONFIG_NO_HZ */
 114
 115 /* A context switch is a grace period for RCU-sched and RCU-bh. */
 116 static inline int rcu_blocking_is_gp(void)
 117 {
 118         return num_online_cpus() == 1;
 119 }
 120
 121 #endif /* __LINUX_RCUTREE_H */