blob: d038aa6e5ee1b4dd64cba0e8e193439c16f010f7 [file] [log] [blame]
Paul E. McKenneye260be62008-01-25 21:08:24 +01001/*
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#ifdef __KERNEL__
37
38#include <linux/cache.h>
39#include <linux/spinlock.h>
40#include <linux/threads.h>
41#include <linux/percpu.h>
42#include <linux/cpumask.h>
43#include <linux/seqlock.h>
44
45#define rcu_qsctr_inc(cpu)
46#define rcu_bh_qsctr_inc(cpu)
47#define call_rcu_bh(head, rcu) call_rcu(head, rcu)
48
Patrick McHardyb55ab612008-02-08 04:21:59 -080049extern void __rcu_read_lock(void) __acquires(RCU);
50extern void __rcu_read_unlock(void) __releases(RCU);
Paul E. McKenneye260be62008-01-25 21:08:24 +010051extern int rcu_pending(int cpu);
52extern int rcu_needs_cpu(int cpu);
53
54#define __rcu_read_lock_bh() { rcu_read_lock(); local_bh_disable(); }
55#define __rcu_read_unlock_bh() { local_bh_enable(); rcu_read_unlock(); }
56
57extern void __synchronize_sched(void);
58
59extern void __rcu_init(void);
60extern void rcu_check_callbacks(int cpu, int user);
61extern void rcu_restart_cpu(int cpu);
62extern long rcu_batches_completed(void);
63
64/*
65 * Return the number of RCU batches processed thus far. Useful for debug
66 * and statistic. The _bh variant is identifcal to straight RCU
67 */
68static inline long rcu_batches_completed_bh(void)
69{
70 return rcu_batches_completed();
71}
72
73#ifdef CONFIG_RCU_TRACE
74struct rcupreempt_trace;
75extern long *rcupreempt_flipctr(int cpu);
76extern long rcupreempt_data_completed(void);
77extern int rcupreempt_flip_flag(int cpu);
78extern int rcupreempt_mb_flag(int cpu);
79extern char *rcupreempt_try_flip_state_name(void);
80extern struct rcupreempt_trace *rcupreempt_trace_cpu(int cpu);
81#endif
82
83struct softirq_action;
84
Steven Rostedt2232c2d2008-02-29 18:46:50 +010085#ifdef CONFIG_NO_HZ
86DECLARE_PER_CPU(long, dynticks_progress_counter);
87
88static inline void rcu_enter_nohz(void)
89{
Paul E. McKenneyae66be92008-03-19 17:00:57 -070090 smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */
Steven Rostedt2232c2d2008-02-29 18:46:50 +010091 __get_cpu_var(dynticks_progress_counter)++;
92 WARN_ON(__get_cpu_var(dynticks_progress_counter) & 0x1);
Steven Rostedt2232c2d2008-02-29 18:46:50 +010093}
94
95static inline void rcu_exit_nohz(void)
96{
Steven Rostedt2232c2d2008-02-29 18:46:50 +010097 __get_cpu_var(dynticks_progress_counter)++;
Paul E. McKenneyae66be92008-03-19 17:00:57 -070098 smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */
Steven Rostedt2232c2d2008-02-29 18:46:50 +010099 WARN_ON(!(__get_cpu_var(dynticks_progress_counter) & 0x1));
100}
101
102#else /* CONFIG_NO_HZ */
103#define rcu_enter_nohz() do { } while (0)
104#define rcu_exit_nohz() do { } while (0)
105#endif /* CONFIG_NO_HZ */
106
Paul E. McKenneye260be62008-01-25 21:08:24 +0100107#endif /* __KERNEL__ */
108#endif /* __LINUX_RCUPREEMPT_H */