Commit | Line | Data |
---|---|---|
7ac06cef MD |
1 | #ifndef _URCU_QSBR_STATIC_H |
2 | #define _URCU_QSBR_STATIC_H | |
3 | ||
4 | /* | |
5 | * urcu-qsbr-static.h | |
6 | * | |
7 | * Userspace RCU QSBR header. | |
8 | * | |
9 | * TO BE INCLUDED ONLY IN LGPL-COMPATIBLE CODE. See urcu-qsbr.h for linking | |
10 | * dynamically with the userspace rcu QSBR library. | |
11 | * | |
12 | * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> | |
13 | * Copyright (c) 2009 Paul E. McKenney, IBM Corporation. | |
14 | * | |
15 | * This library is free software; you can redistribute it and/or | |
16 | * modify it under the terms of the GNU Lesser General Public | |
17 | * License as published by the Free Software Foundation; either | |
18 | * version 2.1 of the License, or (at your option) any later version. | |
19 | * | |
20 | * This library is distributed in the hope that it will be useful, | |
21 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
22 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
23 | * Lesser General Public License for more details. | |
24 | * | |
25 | * You should have received a copy of the GNU Lesser General Public | |
26 | * License along with this library; if not, write to the Free Software | |
27 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
28 | * | |
29 | * IBM's contributions to this file may be relicensed under LGPLv2 or later. | |
30 | */ | |
31 | ||
32 | #include <stdlib.h> | |
33 | #include <pthread.h> | |
34 | #include <assert.h> | |
f0f7dbdd | 35 | #include <limits.h> |
bc6c15bb MD |
36 | #include <syscall.h> |
37 | #include <unistd.h> | |
7ac06cef | 38 | |
ec4e58a3 MD |
39 | #include <urcu/compiler.h> |
40 | #include <urcu/arch.h> | |
7e30abe3 | 41 | #include <urcu/system.h> |
48d848c7 | 42 | #include <urcu/uatomic_arch.h> |
4f8e3380 | 43 | #include <urcu/list.h> |
0854ccff | 44 | #include <urcu/urcu-futex.h> |
bc6c15bb | 45 | |
36bc70a8 MD |
46 | #ifdef __cplusplus |
47 | extern "C" { | |
48 | #endif | |
49 | ||
7ac06cef MD |
50 | /* |
51 | * This code section can only be included in LGPL 2.1 compatible source code. | |
52 | * See below for the function call wrappers which can be used in code meant to | |
53 | * be only linked with the Userspace RCU library. This comes with a small | |
54 | * performance degradation on the read-side due to the added function calls. | |
55 | * This is required to permit relinking with newer versions of the library. | |
56 | */ | |
57 | ||
58 | /* | |
59 | * If a reader is really non-cooperative and refuses to commit its | |
02be5561 | 60 | * rcu_reader.ctr count to memory (there is no barrier in the reader |
7ac06cef MD |
61 | * per-se), kick it after a few loops waiting for it. |
62 | */ | |
63 | #define KICK_READER_LOOPS 10000 | |
64 | ||
bc6c15bb MD |
65 | /* |
66 | * Active attempts to check for reader Q.S. before calling futex(). | |
67 | */ | |
68 | #define RCU_QS_ACTIVE_ATTEMPTS 100 | |
69 | ||
7ac06cef MD |
70 | #ifdef DEBUG_RCU |
71 | #define rcu_assert(args...) assert(args) | |
72 | #else | |
73 | #define rcu_assert(args...) | |
74 | #endif | |
75 | ||
76 | #ifdef DEBUG_YIELD | |
77 | #include <sched.h> | |
78 | #include <time.h> | |
79 | #include <pthread.h> | |
80 | #include <unistd.h> | |
81 | ||
82 | #define YIELD_READ (1 << 0) | |
83 | #define YIELD_WRITE (1 << 1) | |
84 | ||
85 | /* maximum sleep delay, in us */ | |
86 | #define MAX_SLEEP 50 | |
87 | ||
88 | extern unsigned int yield_active; | |
89 | extern unsigned int __thread rand_yield; | |
90 | ||
91 | static inline void debug_yield_read(void) | |
92 | { | |
93 | if (yield_active & YIELD_READ) | |
94 | if (rand_r(&rand_yield) & 0x1) | |
95 | usleep(rand_r(&rand_yield) % MAX_SLEEP); | |
96 | } | |
97 | ||
98 | static inline void debug_yield_write(void) | |
99 | { | |
100 | if (yield_active & YIELD_WRITE) | |
101 | if (rand_r(&rand_yield) & 0x1) | |
102 | usleep(rand_r(&rand_yield) % MAX_SLEEP); | |
103 | } | |
104 | ||
105 | static inline void debug_yield_init(void) | |
106 | { | |
107 | rand_yield = time(NULL) ^ pthread_self(); | |
108 | } | |
109 | #else | |
110 | static inline void debug_yield_read(void) | |
111 | { | |
112 | } | |
113 | ||
114 | static inline void debug_yield_write(void) | |
115 | { | |
116 | } | |
117 | ||
118 | static inline void debug_yield_init(void) | |
119 | { | |
120 | ||
121 | } | |
122 | #endif | |
123 | ||
ac258107 | 124 | #define RCU_GP_ONLINE (1UL << 0) |
55570466 | 125 | #define RCU_GP_CTR (1UL << 1) |
ac258107 | 126 | |
7ac06cef MD |
127 | /* |
128 | * Global quiescent period counter with low-order bits unused. | |
129 | * Using a int rather than a char to eliminate false register dependencies | |
130 | * causing stalls on some architectures. | |
131 | */ | |
02be5561 | 132 | extern unsigned long rcu_gp_ctr; |
7ac06cef | 133 | |
02be5561 | 134 | struct rcu_reader { |
bd1a5e15 | 135 | /* Data used by both reader and synchronize_rcu() */ |
4f8e3380 | 136 | unsigned long ctr; |
bd1a5e15 | 137 | /* Data used for registry */ |
18c3778a | 138 | struct list_head node __attribute__((aligned(CACHE_LINE_SIZE))); |
4f8e3380 MD |
139 | pthread_t tid; |
140 | }; | |
141 | ||
02be5561 | 142 | extern struct rcu_reader __thread rcu_reader; |
7ac06cef | 143 | |
bc6c15bb MD |
144 | extern int gp_futex; |
145 | ||
146 | /* | |
147 | * Wake-up waiting synchronize_rcu(). Called from many concurrent threads. | |
148 | */ | |
149 | static inline void wake_up_gp(void) | |
150 | { | |
ec4e58a3 MD |
151 | if (unlikely(uatomic_read(&gp_futex) == -1)) { |
152 | uatomic_set(&gp_futex, 0); | |
0854ccff | 153 | futex_noasync(&gp_futex, FUTEX_WAKE, 1, |
bc6c15bb MD |
154 | NULL, NULL, 0); |
155 | } | |
156 | } | |
157 | ||
e26fa029 | 158 | static inline int rcu_gp_ongoing(unsigned long *ctr) |
7ac06cef | 159 | { |
e26fa029 | 160 | unsigned long v; |
4e560c17 | 161 | |
e26fa029 | 162 | v = LOAD_SHARED(*ctr); |
92cb20a8 | 163 | return v && (v != rcu_gp_ctr); |
7ac06cef MD |
164 | } |
165 | ||
166 | static inline void _rcu_read_lock(void) | |
167 | { | |
02be5561 | 168 | rcu_assert(rcu_reader.ctr); |
7ac06cef MD |
169 | } |
170 | ||
171 | static inline void _rcu_read_unlock(void) | |
172 | { | |
173 | } | |
174 | ||
175 | static inline void _rcu_quiescent_state(void) | |
176 | { | |
177 | smp_mb(); | |
02be5561 MD |
178 | _STORE_SHARED(rcu_reader.ctr, _LOAD_SHARED(rcu_gp_ctr)); |
179 | smp_mb(); /* write rcu_reader.ctr before read futex */ | |
bc6c15bb | 180 | wake_up_gp(); |
7ac06cef MD |
181 | smp_mb(); |
182 | } | |
183 | ||
184 | static inline void _rcu_thread_offline(void) | |
185 | { | |
186 | smp_mb(); | |
02be5561 MD |
187 | STORE_SHARED(rcu_reader.ctr, 0); |
188 | smp_mb(); /* write rcu_reader.ctr before read futex */ | |
bc6c15bb | 189 | wake_up_gp(); |
7ac06cef MD |
190 | } |
191 | ||
192 | static inline void _rcu_thread_online(void) | |
193 | { | |
02be5561 | 194 | _STORE_SHARED(rcu_reader.ctr, LOAD_SHARED(rcu_gp_ctr)); |
7ac06cef MD |
195 | smp_mb(); |
196 | } | |
197 | ||
36bc70a8 MD |
198 | #ifdef __cplusplus |
199 | } | |
200 | #endif | |
201 | ||
7ac06cef | 202 | #endif /* _URCU_QSBR_STATIC_H */ |