rcutree.h revision bbad937983147c017c25406860287cb94da9af7c 
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
33struct notifier_block;
34
35extern void rcu_sched_qs(int cpu);
36extern void rcu_bh_qs(int cpu);
37extern void rcu_note_context_switch(int cpu);
38extern int rcu_needs_cpu(int cpu);
39extern int rcu_expedited_torture_stats(char *page);
40
41#ifdef CONFIG_TREE_PREEMPT_RCU
42
43extern void __rcu_read_lock(void);
44extern void __rcu_read_unlock(void);
45extern void synchronize_rcu(void);
46extern 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
56static inline void __rcu_read_lock(void)
57{
58	preempt_disable();
59}
60
61static inline void __rcu_read_unlock(void)
62{
63	preempt_enable();
64}
65
66#define synchronize_rcu synchronize_sched
67
68static inline void exit_rcu(void)
69{
70}
71
72static inline int rcu_preempt_depth(void)
73{
74	return 0;
75}
76
77#endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */
78
79static inline void __rcu_read_lock_bh(void)
80{
81	local_bh_disable();
82}
83static inline void __rcu_read_unlock_bh(void)
84{
85	local_bh_enable();
86}
87
88extern void call_rcu_sched(struct rcu_head *head,
89			   void (*func)(struct rcu_head *rcu));
90extern void synchronize_rcu_bh(void);
91extern void synchronize_sched(void);
92extern void synchronize_rcu_expedited(void);
93
94static inline void synchronize_rcu_bh_expedited(void)
95{
96	synchronize_sched_expedited();
97}
98
99extern void rcu_check_callbacks(int cpu, int user);
100
101extern long rcu_batches_completed(void);
102extern long rcu_batches_completed_bh(void);
103extern long rcu_batches_completed_sched(void);
104extern void rcu_force_quiescent_state(void);
105extern void rcu_bh_force_quiescent_state(void);
106extern void rcu_sched_force_quiescent_state(void);
107
108#ifdef CONFIG_NO_HZ
109void rcu_enter_nohz(void);
110void rcu_exit_nohz(void);
111#else /* CONFIG_NO_HZ */
112static inline void rcu_enter_nohz(void)
113{
114}
115static inline void rcu_exit_nohz(void)
116{
117}
118#endif /* CONFIG_NO_HZ */
119
120/* A context switch is a grace period for RCU-sched and RCU-bh. */
121static inline int rcu_blocking_is_gp(void)
122{
123	return num_online_cpus() == 1;
124}
125
126extern void rcu_scheduler_starting(void);
127extern int rcu_scheduler_active __read_mostly;
128
129#endif /* __LINUX_RCUTREE_H */
130