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01c1c660 PM |
1 | /* |
2 | * Read-Copy Update mechanism for mutual exclusion (classic 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, 2001 | |
19 | * | |
20 | * Author: Dipankar Sarma <dipankar@in.ibm.com> | |
21 | * | |
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) | |
27 | * | |
28 | * For detailed explanation of Read-Copy Update mechanism see - | |
29 | * Documentation/RCU | |
30 | * | |
31 | */ | |
32 | ||
33 | #ifndef __LINUX_RCUCLASSIC_H | |
34 | #define __LINUX_RCUCLASSIC_H | |
35 | ||
01c1c660 PM |
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 | ||
2133b5d7 | 43 | #ifdef CONFIG_RCU_CPU_STALL_DETECTOR |
29cbda77 | 44 | #define RCU_SECONDS_TILL_STALL_CHECK (10 * HZ) /* for rcp->jiffies_stall */ |
2133b5d7 PM |
45 | #define RCU_SECONDS_TILL_STALL_RECHECK (30 * HZ) /* for rcp->jiffies_stall */ |
46 | #endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ | |
01c1c660 PM |
47 | |
48 | /* Global control variables for rcupdate callback mechanism. */ | |
49 | struct rcu_ctrlblk { | |
50 | long cur; /* Current batch number. */ | |
51 | long completed; /* Number of the last completed batch */ | |
3cac97cb | 52 | long pending; /* Number of the last pending batch */ |
2133b5d7 PM |
53 | #ifdef CONFIG_RCU_CPU_STALL_DETECTOR |
54 | unsigned long gp_start; /* Time at which GP started in jiffies. */ | |
55 | unsigned long jiffies_stall; | |
56 | /* Time at which to check for CPU stalls. */ | |
57 | #endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ | |
01c1c660 PM |
58 | |
59 | int signaled; | |
60 | ||
61 | spinlock_t lock ____cacheline_internodealigned_in_smp; | |
bd232f97 RR |
62 | DECLARE_BITMAP(cpumask, NR_CPUS); /* CPUs that need to switch for */ |
63 | /* current batch to proceed. */ | |
01c1c660 PM |
64 | } ____cacheline_internodealigned_in_smp; |
65 | ||
66 | /* Is batch a before batch b ? */ | |
67 | static inline int rcu_batch_before(long a, long b) | |
68 | { | |
69 | return (a - b) < 0; | |
70 | } | |
71 | ||
72 | /* Is batch a after batch b ? */ | |
73 | static inline int rcu_batch_after(long a, long b) | |
74 | { | |
75 | return (a - b) > 0; | |
76 | } | |
77 | ||
5127bed5 | 78 | /* Per-CPU data for Read-Copy UPdate. */ |
01c1c660 PM |
79 | struct rcu_data { |
80 | /* 1) quiescent state handling : */ | |
81 | long quiescbatch; /* Batch # for grace period */ | |
82 | int passed_quiesc; /* User-mode/idle loop etc. */ | |
83 | int qs_pending; /* core waits for quiesc state */ | |
84 | ||
85 | /* 2) batch handling */ | |
5127bed5 LJ |
86 | /* |
87 | * if nxtlist is not NULL, then: | |
88 | * batch: | |
89 | * The batch # for the last entry of nxtlist | |
90 | * [*nxttail[1], NULL = *nxttail[2]): | |
91 | * Entries that batch # <= batch | |
92 | * [*nxttail[0], *nxttail[1]): | |
93 | * Entries that batch # <= batch - 1 | |
94 | * [nxtlist, *nxttail[0]): | |
95 | * Entries that batch # <= batch - 2 | |
96 | * The grace period for these entries has completed, and | |
97 | * the other grace-period-completed entries may be moved | |
98 | * here temporarily in rcu_process_callbacks(). | |
99 | */ | |
100 | long batch; | |
01c1c660 | 101 | struct rcu_head *nxtlist; |
5127bed5 | 102 | struct rcu_head **nxttail[3]; |
01c1c660 | 103 | long qlen; /* # of queued callbacks */ |
01c1c660 PM |
104 | struct rcu_head *donelist; |
105 | struct rcu_head **donetail; | |
106 | long blimit; /* Upper limit on a processed batch */ | |
107 | int cpu; | |
108 | struct rcu_head barrier; | |
109 | }; | |
110 | ||
111 | DECLARE_PER_CPU(struct rcu_data, rcu_data); | |
112 | DECLARE_PER_CPU(struct rcu_data, rcu_bh_data); | |
113 | ||
114 | /* | |
115 | * Increment the quiescent state counter. | |
116 | * The counter is a bit degenerated: We do not need to know | |
117 | * how many quiescent states passed, just if there was at least | |
118 | * one since the start of the grace period. Thus just a flag. | |
119 | */ | |
120 | static inline void rcu_qsctr_inc(int cpu) | |
121 | { | |
122 | struct rcu_data *rdp = &per_cpu(rcu_data, cpu); | |
123 | rdp->passed_quiesc = 1; | |
124 | } | |
125 | static inline void rcu_bh_qsctr_inc(int cpu) | |
126 | { | |
127 | struct rcu_data *rdp = &per_cpu(rcu_bh_data, cpu); | |
128 | rdp->passed_quiesc = 1; | |
129 | } | |
130 | ||
131 | extern int rcu_pending(int cpu); | |
132 | extern int rcu_needs_cpu(int cpu); | |
133 | ||
134 | #ifdef CONFIG_DEBUG_LOCK_ALLOC | |
135 | extern struct lockdep_map rcu_lock_map; | |
136 | # define rcu_read_acquire() \ | |
7531e2f3 | 137 | lock_acquire(&rcu_lock_map, 0, 0, 2, 1, NULL, _THIS_IP_) |
01c1c660 PM |
138 | # define rcu_read_release() lock_release(&rcu_lock_map, 1, _THIS_IP_) |
139 | #else | |
140 | # define rcu_read_acquire() do { } while (0) | |
141 | # define rcu_read_release() do { } while (0) | |
142 | #endif | |
143 | ||
144 | #define __rcu_read_lock() \ | |
145 | do { \ | |
146 | preempt_disable(); \ | |
147 | __acquire(RCU); \ | |
148 | rcu_read_acquire(); \ | |
149 | } while (0) | |
150 | #define __rcu_read_unlock() \ | |
151 | do { \ | |
152 | rcu_read_release(); \ | |
153 | __release(RCU); \ | |
154 | preempt_enable(); \ | |
155 | } while (0) | |
156 | #define __rcu_read_lock_bh() \ | |
157 | do { \ | |
158 | local_bh_disable(); \ | |
159 | __acquire(RCU_BH); \ | |
160 | rcu_read_acquire(); \ | |
161 | } while (0) | |
162 | #define __rcu_read_unlock_bh() \ | |
163 | do { \ | |
164 | rcu_read_release(); \ | |
165 | __release(RCU_BH); \ | |
166 | local_bh_enable(); \ | |
167 | } while (0) | |
168 | ||
169 | #define __synchronize_sched() synchronize_rcu() | |
170 | ||
4446a36f PM |
171 | #define call_rcu_sched(head, func) call_rcu(head, func) |
172 | ||
01c1c660 | 173 | extern void __rcu_init(void); |
4446a36f | 174 | #define rcu_init_sched() do { } while (0) |
01c1c660 PM |
175 | extern void rcu_check_callbacks(int cpu, int user); |
176 | extern void rcu_restart_cpu(int cpu); | |
177 | ||
e260be67 PM |
178 | extern long rcu_batches_completed(void); |
179 | extern long rcu_batches_completed_bh(void); | |
180 | ||
2232c2d8 SR |
181 | #define rcu_enter_nohz() do { } while (0) |
182 | #define rcu_exit_nohz() do { } while (0) | |
183 | ||
01c1c660 | 184 | #endif /* __LINUX_RCUCLASSIC_H */ |