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 void rcu_note_context_switch(int cpu);
  38 extern int rcu_needs_cpu(int cpu);
  39
  40 #ifdef CONFIG_TREE_PREEMPT_RCU
  41
  42 extern void __rcu_read_lock(void);
  43 extern void __rcu_read_unlock(void);
  44 extern void synchronize_rcu(void);
  45 extern void exit_rcu(void);
  46
  47 /*
  48  * Defined as macro as it is a very low level header
  49  * included from areas that don't even know about current
  50  */
  51 #define rcu_preempt_depth() (current->rcu_read_lock_nesting)
  52
  53 #else /* #ifdef CONFIG_TREE_PREEMPT_RCU */
  54
  55 static inline void __rcu_read_lock(void)
  56 {
  57         preempt_disable();
  58 }
  59
  60 static inline void __rcu_read_unlock(void)
  61 {
  62         preempt_enable();
  63 }
  64
  65 #define synchronize_rcu synchronize_sched
  66
  67 static inline void exit_rcu(void)
  68 {
  69 }
  70
  71 static inline int rcu_preempt_depth(void)
  72 {
  73         return 0;
  74 }
  75
  76 #endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */
  77
  78 static inline void __rcu_read_lock_bh(void)
  79 {
  80         local_bh_disable();
  81 }
  82 static inline void __rcu_read_unlock_bh(void)
  83 {
  84         local_bh_enable();
  85 }
  86
  87 extern void call_rcu_sched(struct rcu_head *head,
  88                            void (*func)(struct rcu_head *rcu));
  89 extern void synchronize_rcu_bh(void);
  90 extern void synchronize_sched(void);
  91 extern void synchronize_rcu_expedited(void);
  92
  93 static inline void synchronize_rcu_bh_expedited(void)
  94 {
  95         synchronize_sched_expedited();
  96 }
  97
  98 extern void rcu_check_callbacks(int cpu, int user);
  99
 100 extern long rcu_batches_completed(void);
 101 extern long rcu_batches_completed_bh(void);
 102 extern long rcu_batches_completed_sched(void);
 103 extern void rcu_force_quiescent_state(void);
 104 extern void rcu_bh_force_quiescent_state(void);
 105 extern void rcu_sched_force_quiescent_state(void);
 106
 107 #ifdef CONFIG_NO_HZ
 108 void rcu_enter_nohz(void);
 109 void rcu_exit_nohz(void);
 110 #else /* CONFIG_NO_HZ */
 111 static inline void rcu_enter_nohz(void)
 112 {
 113 }
 114 static inline void rcu_exit_nohz(void)
 115 {
 116 }
 117 #endif /* CONFIG_NO_HZ */
 118
 119 /* A context switch is a grace period for RCU-sched and RCU-bh. */
 120 static inline int rcu_blocking_is_gp(void)
 121 {
 122         return num_online_cpus() == 1;
 123 }
 124
 125 extern void rcu_scheduler_starting(void);
 126 extern int rcu_scheduler_active __read_mostly;
 127
 128 #endif /* __LINUX_RCUTREE_H */