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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 | ||
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 | ||
46 | /* Global control variables for rcupdate callback mechanism. */ | |
47 | struct rcu_ctrlblk { | |
48 | long cur; /* Current batch number. */ | |
49 | long completed; /* Number of the last completed batch */ | |
50 | int next_pending; /* Is the next batch already waiting? */ | |
51 | ||
52 | int signaled; | |
53 | ||
54 | spinlock_t lock ____cacheline_internodealigned_in_smp; | |
55 | cpumask_t cpumask; /* CPUs that need to switch in order */ | |
56 | /* for current batch to proceed. */ | |
57 | } ____cacheline_internodealigned_in_smp; | |
58 | ||
59 | /* Is batch a before batch b ? */ | |
60 | static inline int rcu_batch_before(long a, long b) | |
61 | { | |
62 | return (a - b) < 0; | |
63 | } | |
64 | ||
65 | /* Is batch a after batch b ? */ | |
66 | static inline int rcu_batch_after(long a, long b) | |
67 | { | |
68 | return (a - b) > 0; | |
69 | } | |
70 | ||
71 | /* | |
72 | * Per-CPU data for Read-Copy UPdate. | |
73 | * nxtlist - new callbacks are added here | |
74 | * curlist - current batch for which quiescent cycle started if any | |
75 | */ | |
76 | struct rcu_data { | |
77 | /* 1) quiescent state handling : */ | |
78 | long quiescbatch; /* Batch # for grace period */ | |
79 | int passed_quiesc; /* User-mode/idle loop etc. */ | |
80 | int qs_pending; /* core waits for quiesc state */ | |
81 | ||
82 | /* 2) batch handling */ | |
83 | long batch; /* Batch # for current RCU batch */ | |
84 | struct rcu_head *nxtlist; | |
85 | struct rcu_head **nxttail; | |
86 | long qlen; /* # of queued callbacks */ | |
87 | struct rcu_head *curlist; | |
88 | struct rcu_head **curtail; | |
89 | struct rcu_head *donelist; | |
90 | struct rcu_head **donetail; | |
91 | long blimit; /* Upper limit on a processed batch */ | |
92 | int cpu; | |
93 | struct rcu_head barrier; | |
94 | }; | |
95 | ||
96 | DECLARE_PER_CPU(struct rcu_data, rcu_data); | |
97 | DECLARE_PER_CPU(struct rcu_data, rcu_bh_data); | |
98 | ||
99 | /* | |
100 | * Increment the quiescent state counter. | |
101 | * The counter is a bit degenerated: We do not need to know | |
102 | * how many quiescent states passed, just if there was at least | |
103 | * one since the start of the grace period. Thus just a flag. | |
104 | */ | |
105 | static inline void rcu_qsctr_inc(int cpu) | |
106 | { | |
107 | struct rcu_data *rdp = &per_cpu(rcu_data, cpu); | |
108 | rdp->passed_quiesc = 1; | |
109 | } | |
110 | static inline void rcu_bh_qsctr_inc(int cpu) | |
111 | { | |
112 | struct rcu_data *rdp = &per_cpu(rcu_bh_data, cpu); | |
113 | rdp->passed_quiesc = 1; | |
114 | } | |
115 | ||
116 | extern int rcu_pending(int cpu); | |
117 | extern int rcu_needs_cpu(int cpu); | |
118 | ||
119 | #ifdef CONFIG_DEBUG_LOCK_ALLOC | |
120 | extern struct lockdep_map rcu_lock_map; | |
121 | # define rcu_read_acquire() \ | |
122 | lock_acquire(&rcu_lock_map, 0, 0, 2, 1, _THIS_IP_) | |
123 | # define rcu_read_release() lock_release(&rcu_lock_map, 1, _THIS_IP_) | |
124 | #else | |
125 | # define rcu_read_acquire() do { } while (0) | |
126 | # define rcu_read_release() do { } while (0) | |
127 | #endif | |
128 | ||
129 | #define __rcu_read_lock() \ | |
130 | do { \ | |
131 | preempt_disable(); \ | |
132 | __acquire(RCU); \ | |
133 | rcu_read_acquire(); \ | |
134 | } while (0) | |
135 | #define __rcu_read_unlock() \ | |
136 | do { \ | |
137 | rcu_read_release(); \ | |
138 | __release(RCU); \ | |
139 | preempt_enable(); \ | |
140 | } while (0) | |
141 | #define __rcu_read_lock_bh() \ | |
142 | do { \ | |
143 | local_bh_disable(); \ | |
144 | __acquire(RCU_BH); \ | |
145 | rcu_read_acquire(); \ | |
146 | } while (0) | |
147 | #define __rcu_read_unlock_bh() \ | |
148 | do { \ | |
149 | rcu_read_release(); \ | |
150 | __release(RCU_BH); \ | |
151 | local_bh_enable(); \ | |
152 | } while (0) | |
153 | ||
154 | #define __synchronize_sched() synchronize_rcu() | |
155 | ||
156 | extern void __rcu_init(void); | |
157 | extern void rcu_check_callbacks(int cpu, int user); | |
158 | extern void rcu_restart_cpu(int cpu); | |
159 | ||
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160 | extern long rcu_batches_completed(void); |
161 | extern long rcu_batches_completed_bh(void); | |
162 | ||
01c1c660 PM |
163 | #endif /* __KERNEL__ */ |
164 | #endif /* __LINUX_RCUCLASSIC_H */ |