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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 int rcu_needs_cpu(int cpu);
38extern int rcu_expedited_torture_stats(char *page);
39
40#ifdef CONFIG_TREE_PREEMPT_RCU
41
42extern void __rcu_read_lock(void);
43extern void __rcu_read_unlock(void);
44extern void synchronize_rcu(void);
45extern 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
55static inline void __rcu_read_lock(void)
56{
57 preempt_disable();
58}
59
60static inline void __rcu_read_unlock(void)
61{
62 preempt_enable();
63}
64
65#define synchronize_rcu synchronize_sched
66
67static inline void exit_rcu(void)
68{
69}
70
71static inline int rcu_preempt_depth(void)
72{
73 return 0;
74}
75
76#endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */
77
78static inline void __rcu_read_lock_bh(void)
79{
80 local_bh_disable();
81}
82static inline void __rcu_read_unlock_bh(void)
83{
84 local_bh_enable();
85}
86
87extern void call_rcu_sched(struct rcu_head *head,
88 void (*func)(struct rcu_head *rcu));
89extern void synchronize_rcu_expedited(void);
90
91static inline void synchronize_rcu_bh_expedited(void)
92{
93 synchronize_sched_expedited();
94}
95
96extern void rcu_check_callbacks(int cpu, int user);
97
98extern long rcu_batches_completed(void);
99extern long rcu_batches_completed_bh(void);
100extern long rcu_batches_completed_sched(void);
101extern void rcu_force_quiescent_state(void);
102extern void rcu_bh_force_quiescent_state(void);
103extern void rcu_sched_force_quiescent_state(void);
104
105#ifdef CONFIG_NO_HZ
106void rcu_enter_nohz(void);
107void rcu_exit_nohz(void);
108#else /* CONFIG_NO_HZ */
109static inline void rcu_enter_nohz(void)
110{
111}
112static inline void rcu_exit_nohz(void)
113{
114}
115#endif /* CONFIG_NO_HZ */
116
117/* A context switch is a grace period for RCU-sched and RCU-bh. */
118static inline int rcu_blocking_is_gp(void)
119{
120 return num_online_cpus() == 1;
121}
122
123#endif /* __LINUX_RCUTREE_H */