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Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
1/*
2 * Read-Copy Update mechanism for mutual exclusion (RT implementation)
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 (C) IBM Corporation, 2006
19 *
20 * Author: Paul McKenney <paulmck@us.ibm.com>
21 *
22 * Based on the original work by Paul McKenney <paul.mckenney@us.ibm.com>
23 * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
24 * Papers:
25 * http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf
26 * http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001)
27 *
28 * For detailed explanation of Read-Copy Update mechanism see -
29 * Documentation/RCU
30 *
31 */
32
33#ifndef __LINUX_RCUPREEMPT_H
34#define __LINUX_RCUPREEMPT_H
35
36#include <linux/cache.h>
37#include <linux/spinlock.h>
38#include <linux/threads.h>
39#include <linux/percpu.h>
40#include <linux/cpumask.h>
41#include <linux/seqlock.h>
42
43struct rcu_dyntick_sched {
44 int dynticks;
45 int dynticks_snap;
46 int sched_qs;
47 int sched_qs_snap;
48 int sched_dynticks_snap;
49};
50
51DECLARE_PER_CPU(struct rcu_dyntick_sched, rcu_dyntick_sched);
52
53static inline void rcu_qsctr_inc(int cpu)
54{
55 struct rcu_dyntick_sched *rdssp = &per_cpu(rcu_dyntick_sched, cpu);
56
57 rdssp->sched_qs++;
58}
59#define rcu_bh_qsctr_inc(cpu)
60#define call_rcu_bh(head, rcu) call_rcu(head, rcu)
61
62/**
63 * call_rcu_sched - Queue RCU callback for invocation after sched grace period.
64 * @head: structure to be used for queueing the RCU updates.
65 * @func: actual update function to be invoked after the grace period
66 *
67 * The update function will be invoked some time after a full
68 * synchronize_sched()-style grace period elapses, in other words after
69 * all currently executing preempt-disabled sections of code (including
70 * hardirq handlers, NMI handlers, and local_irq_save() blocks) have
71 * completed.
72 */
73extern void call_rcu_sched(struct rcu_head *head,
74 void (*func)(struct rcu_head *head));
75
76extern void __rcu_read_lock(void) __acquires(RCU);
77extern void __rcu_read_unlock(void) __releases(RCU);
78extern int rcu_pending(int cpu);
79extern int rcu_needs_cpu(int cpu);
80
81#define __rcu_read_lock_bh() { rcu_read_lock(); local_bh_disable(); }
82#define __rcu_read_unlock_bh() { local_bh_enable(); rcu_read_unlock(); }
83
84extern void __synchronize_sched(void);
85
86extern void __rcu_init(void);
87extern void rcu_init_sched(void);
88extern void rcu_check_callbacks(int cpu, int user);
89extern void rcu_restart_cpu(int cpu);
90extern long rcu_batches_completed(void);
91
92/*
93 * Return the number of RCU batches processed thus far. Useful for debug
94 * and statistic. The _bh variant is identifcal to straight RCU
95 */
96static inline long rcu_batches_completed_bh(void)
97{
98 return rcu_batches_completed();
99}
100
101#ifdef CONFIG_RCU_TRACE
102struct rcupreempt_trace;
103extern long *rcupreempt_flipctr(int cpu);
104extern long rcupreempt_data_completed(void);
105extern int rcupreempt_flip_flag(int cpu);
106extern int rcupreempt_mb_flag(int cpu);
107extern char *rcupreempt_try_flip_state_name(void);
108extern struct rcupreempt_trace *rcupreempt_trace_cpu(int cpu);
109#endif
110
111struct softirq_action;
112
113#ifdef CONFIG_NO_HZ
114DECLARE_PER_CPU(struct rcu_dyntick_sched, rcu_dyntick_sched);
115
116static inline void rcu_enter_nohz(void)
117{
118 static DEFINE_RATELIMIT_STATE(rs, 10 * HZ, 1);
119
120 smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */
121 __get_cpu_var(rcu_dyntick_sched).dynticks++;
122 WARN_ON_RATELIMIT(__get_cpu_var(rcu_dyntick_sched).dynticks & 0x1, &rs);
123}
124
125static inline void rcu_exit_nohz(void)
126{
127 static DEFINE_RATELIMIT_STATE(rs, 10 * HZ, 1);
128
129 smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */
130 __get_cpu_var(rcu_dyntick_sched).dynticks++;
131 WARN_ON_RATELIMIT(!(__get_cpu_var(rcu_dyntick_sched).dynticks & 0x1),
132 &rs);
133}
134
135#else /* CONFIG_NO_HZ */
136#define rcu_enter_nohz() do { } while (0)
137#define rcu_exit_nohz() do { } while (0)
138#endif /* CONFIG_NO_HZ */
139
140#endif /* __LINUX_RCUPREEMPT_H */