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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_init(void);
34extern void rcu_note_context_switch(int cpu);
35extern int rcu_needs_cpu(int cpu);
36extern void rcu_cpu_stall_reset(void);
37
38/*
39 * Note a virtualization-based context switch. This is simply a
40 * wrapper around rcu_note_context_switch(), which allows TINY_RCU
41 * to save a few bytes.
42 */
43static inline void rcu_virt_note_context_switch(int cpu)
44{
45 rcu_note_context_switch(cpu);
46}
47
48#ifdef CONFIG_TREE_PREEMPT_RCU
49
50extern void exit_rcu(void);
51
52#else /* #ifdef CONFIG_TREE_PREEMPT_RCU */
53
54static inline void exit_rcu(void)
55{
56}
57
58#endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */
59
60extern void synchronize_rcu_bh(void);
61extern void synchronize_sched_expedited(void);
62extern void synchronize_rcu_expedited(void);
63
64void kfree_call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
65
66/**
67 * synchronize_rcu_bh_expedited - Brute-force RCU-bh grace period
68 *
69 * Wait for an RCU-bh grace period to elapse, but use a "big hammer"
70 * approach to force the grace period to end quickly. This consumes
71 * significant time on all CPUs and is unfriendly to real-time workloads,
72 * so is thus not recommended for any sort of common-case code. In fact,
73 * if you are using synchronize_rcu_bh_expedited() in a loop, please
74 * restructure your code to batch your updates, and then use a single
75 * synchronize_rcu_bh() instead.
76 *
77 * Note that it is illegal to call this function while holding any lock
78 * that is acquired by a CPU-hotplug notifier. And yes, it is also illegal
79 * to call this function from a CPU-hotplug notifier. Failing to observe
80 * these restriction will result in deadlock.
81 */
82static inline void synchronize_rcu_bh_expedited(void)
83{
84 synchronize_sched_expedited();
85}
86
87extern void rcu_barrier(void);
88extern void rcu_barrier_bh(void);
89extern void rcu_barrier_sched(void);
90
91extern unsigned long rcutorture_testseq;
92extern unsigned long rcutorture_vernum;
93extern long rcu_batches_completed(void);
94extern long rcu_batches_completed_bh(void);
95extern long rcu_batches_completed_sched(void);
96
97extern void rcu_force_quiescent_state(void);
98extern void rcu_bh_force_quiescent_state(void);
99extern void rcu_sched_force_quiescent_state(void);
100
101/* A context switch is a grace period for RCU-sched and RCU-bh. */
102static inline int rcu_blocking_is_gp(void)
103{
104 might_sleep(); /* Check for RCU read-side critical section. */
105 return num_online_cpus() == 1;
106}
107
108extern void rcu_scheduler_starting(void);
109extern int rcu_scheduler_active __read_mostly;
110
111#endif /* __LINUX_RCUTREE_H */