ACPI: simplify acpi_pci_irq_add_prt() API
[linux-2.6/linux-acpi-2.6.git] / include / linux / rcuclassic.h
blobbfd92e1e5d2c3ae6d8b8966acf1390e1776828d2
1 /*
2 * Read-Copy Update mechanism for mutual exclusion (classic version)
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.
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.
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.
18 * Copyright IBM Corporation, 2001
20 * Author: Dipankar Sarma <dipankar@in.ibm.com>
22 * Based on the original work by Paul McKenney <paulmck@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)
28 * For detailed explanation of Read-Copy Update mechanism see -
29 * Documentation/RCU
33 #ifndef __LINUX_RCUCLASSIC_H
34 #define __LINUX_RCUCLASSIC_H
36 #include <linux/cache.h>
37 #include <linux/spinlock.h>
38 #include <linux/threads.h>
39 #include <linux/cpumask.h>
40 #include <linux/seqlock.h>
42 #ifdef CONFIG_RCU_CPU_STALL_DETECTOR
43 #define RCU_SECONDS_TILL_STALL_CHECK (10 * HZ) /* for rcp->jiffies_stall */
44 #define RCU_SECONDS_TILL_STALL_RECHECK (30 * HZ) /* for rcp->jiffies_stall */
45 #endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
47 /* Global control variables for rcupdate callback mechanism. */
48 struct rcu_ctrlblk {
49 long cur; /* Current batch number. */
50 long completed; /* Number of the last completed batch */
51 long pending; /* Number of the last pending batch */
52 #ifdef CONFIG_RCU_CPU_STALL_DETECTOR
53 unsigned long gp_start; /* Time at which GP started in jiffies. */
54 unsigned long jiffies_stall;
55 /* Time at which to check for CPU stalls. */
56 #endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
58 int signaled;
60 spinlock_t lock ____cacheline_internodealigned_in_smp;
61 DECLARE_BITMAP(cpumask, NR_CPUS); /* CPUs that need to switch for */
62 /* current batch to proceed. */
63 } ____cacheline_internodealigned_in_smp;
65 /* Is batch a before batch b ? */
66 static inline int rcu_batch_before(long a, long b)
68 return (a - b) < 0;
71 /* Is batch a after batch b ? */
72 static inline int rcu_batch_after(long a, long b)
74 return (a - b) > 0;
77 /* Per-CPU data for Read-Copy UPdate. */
78 struct rcu_data {
79 /* 1) quiescent state handling : */
80 long quiescbatch; /* Batch # for grace period */
81 int passed_quiesc; /* User-mode/idle loop etc. */
82 int qs_pending; /* core waits for quiesc state */
84 /* 2) batch handling */
86 * if nxtlist is not NULL, then:
87 * batch:
88 * The batch # for the last entry of nxtlist
89 * [*nxttail[1], NULL = *nxttail[2]):
90 * Entries that batch # <= batch
91 * [*nxttail[0], *nxttail[1]):
92 * Entries that batch # <= batch - 1
93 * [nxtlist, *nxttail[0]):
94 * Entries that batch # <= batch - 2
95 * The grace period for these entries has completed, and
96 * the other grace-period-completed entries may be moved
97 * here temporarily in rcu_process_callbacks().
99 long batch;
100 struct rcu_head *nxtlist;
101 struct rcu_head **nxttail[3];
102 long qlen; /* # of queued callbacks */
103 struct rcu_head *donelist;
104 struct rcu_head **donetail;
105 long blimit; /* Upper limit on a processed batch */
106 int cpu;
107 struct rcu_head barrier;
111 * Increment the quiescent state counter.
112 * The counter is a bit degenerated: We do not need to know
113 * how many quiescent states passed, just if there was at least
114 * one since the start of the grace period. Thus just a flag.
116 extern void rcu_qsctr_inc(int cpu);
117 extern void rcu_bh_qsctr_inc(int cpu);
119 extern int rcu_pending(int cpu);
120 extern int rcu_needs_cpu(int cpu);
122 #ifdef CONFIG_DEBUG_LOCK_ALLOC
123 extern struct lockdep_map rcu_lock_map;
124 # define rcu_read_acquire() \
125 lock_acquire(&rcu_lock_map, 0, 0, 2, 1, NULL, _THIS_IP_)
126 # define rcu_read_release() lock_release(&rcu_lock_map, 1, _THIS_IP_)
127 #else
128 # define rcu_read_acquire() do { } while (0)
129 # define rcu_read_release() do { } while (0)
130 #endif
132 #define __rcu_read_lock() \
133 do { \
134 preempt_disable(); \
135 __acquire(RCU); \
136 rcu_read_acquire(); \
137 } while (0)
138 #define __rcu_read_unlock() \
139 do { \
140 rcu_read_release(); \
141 __release(RCU); \
142 preempt_enable(); \
143 } while (0)
144 #define __rcu_read_lock_bh() \
145 do { \
146 local_bh_disable(); \
147 __acquire(RCU_BH); \
148 rcu_read_acquire(); \
149 } while (0)
150 #define __rcu_read_unlock_bh() \
151 do { \
152 rcu_read_release(); \
153 __release(RCU_BH); \
154 local_bh_enable(); \
155 } while (0)
157 #define __synchronize_sched() synchronize_rcu()
159 #define call_rcu_sched(head, func) call_rcu(head, func)
161 extern void __rcu_init(void);
162 #define rcu_init_sched() do { } while (0)
163 extern void rcu_check_callbacks(int cpu, int user);
164 extern void rcu_restart_cpu(int cpu);
166 extern long rcu_batches_completed(void);
167 extern long rcu_batches_completed_bh(void);
169 #define rcu_enter_nohz() do { } while (0)
170 #define rcu_exit_nohz() do { } while (0)
172 /* A context switch is a grace period for rcuclassic. */
173 static inline int rcu_blocking_is_gp(void)
175 return num_online_cpus() == 1;
178 #endif /* __LINUX_RCUCLASSIC_H */