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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
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 int rcu_expedited_torture_stats(char *page);
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_expedited(void);
90
91 static inline void synchronize_rcu_bh_expedited(void)
92 {
93 synchronize_sched_expedited();
94 }
95
96 extern void rcu_check_callbacks(int cpu, int user);
97
98 extern long rcu_batches_completed(void);
99 extern long rcu_batches_completed_bh(void);
100 extern long rcu_batches_completed_sched(void);
101 extern void rcu_force_quiescent_state(void);
102 extern void rcu_bh_force_quiescent_state(void);
103 extern void rcu_sched_force_quiescent_state(void);
104
105 #ifdef CONFIG_NO_HZ
106 void rcu_enter_nohz(void);
107 void rcu_exit_nohz(void);
108 #else /* CONFIG_NO_HZ */
109 static inline void rcu_enter_nohz(void)
110 {
111 }
112 static 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. */
118 static inline int rcu_blocking_is_gp(void)
119 {
120 return num_online_cpus() == 1;
121 }
122
123 #endif /* __LINUX_RCUTREE_H */