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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
33extern void rcu_sched_qs(int cpu);
34extern void rcu_bh_qs(int cpu);
35
36extern int rcu_needs_cpu(int cpu);
37
38#ifdef CONFIG_TREE_PREEMPT_RCU
39
40extern void __rcu_read_lock(void);
41extern void __rcu_read_unlock(void);
42extern void exit_rcu(void);
43
44#else /* #ifdef CONFIG_TREE_PREEMPT_RCU */
45
46static inline void __rcu_read_lock(void)
47{
48 preempt_disable();
49}
50
51static inline void __rcu_read_unlock(void)
52{
53 preempt_enable();
54}
55
56#define __synchronize_sched() synchronize_rcu()
57
58static inline void exit_rcu(void)
59{
60}
61
62#endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */
63
64static inline void __rcu_read_lock_bh(void)
65{
66 local_bh_disable();
67}
68static inline void __rcu_read_unlock_bh(void)
69{
70 local_bh_enable();
71}
72
73extern void call_rcu_sched(struct rcu_head *head,
74 void (*func)(struct rcu_head *rcu));
75
76static inline void synchronize_rcu_expedited(void)
77{
78 synchronize_sched_expedited();
79}
80
81static inline void synchronize_rcu_bh_expedited(void)
82{
83 synchronize_sched_expedited();
84}
85
86extern void __rcu_init(void);
87extern void rcu_check_callbacks(int cpu, int user);
88extern void rcu_restart_cpu(int cpu);
89
90extern long rcu_batches_completed(void);
91extern long rcu_batches_completed_bh(void);
92extern long rcu_batches_completed_sched(void);
93
94static inline void rcu_init_sched(void)
95{
96}
97
98#ifdef CONFIG_NO_HZ
99void rcu_enter_nohz(void);
100void rcu_exit_nohz(void);
101#else /* CONFIG_NO_HZ */
102static inline void rcu_enter_nohz(void)
103{
104}
105static inline void rcu_exit_nohz(void)
106{
107}
108#endif /* CONFIG_NO_HZ */
109
110/* A context switch is a grace period for rcutree. */
111static inline int rcu_blocking_is_gp(void)
112{
113 return num_online_cpus() == 1;
114}
115
116#endif /* __LINUX_RCUTREE_H */