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adcfce54 MD |
1 | #ifndef _URCU_STATIC_H |
2 | #define _URCU_STATIC_H | |
3 | ||
4 | /* | |
5 | * urcu-static.h | |
6 | * | |
d2d23035 | 7 | * Userspace RCU header. |
adcfce54 | 8 | * |
d2d23035 MD |
9 | * TO BE INCLUDED ONLY IN LGPL-COMPATIBLE CODE. See urcu.h for linking |
10 | * dynamically with the userspace rcu library. | |
adcfce54 | 11 | * |
6982d6d7 | 12 | * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
d2d23035 | 13 | * Copyright (c) 2009 Paul E. McKenney, IBM Corporation. |
adcfce54 | 14 | * |
d2d23035 MD |
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 | |
adcfce54 MD |
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> | |
bc6c15bb MD |
34 | #include <syscall.h> |
35 | #include <unistd.h> | |
6d841bc2 | 36 | #include <stdint.h> |
adcfce54 | 37 | |
ec4e58a3 MD |
38 | #include <urcu/compiler.h> |
39 | #include <urcu/arch.h> | |
7e30abe3 | 40 | #include <urcu/system.h> |
a2e7bf9c | 41 | #include <urcu/uatomic.h> |
e3b0cef0 | 42 | #include <urcu/list.h> |
41849996 | 43 | #include <urcu/futex.h> |
bc6c15bb | 44 | |
36bc70a8 MD |
45 | #ifdef __cplusplus |
46 | extern "C" { | |
47 | #endif | |
48 | ||
fdf01eed MD |
49 | /* Default is RCU_MEMBARRIER */ |
50 | #if !defined(RCU_MEMBARRIER) && !defined(RCU_MB) && !defined(RCU_SIGNAL) | |
51 | #define RCU_MEMBARRIER | |
52 | #endif | |
53 | ||
54 | #ifdef RCU_MEMBARRIER | |
55 | #include <unistd.h> | |
56 | #include <sys/syscall.h> | |
57 | ||
58 | /* If the headers do not support SYS_membarrier, statically use RCU_MB */ | |
59 | #ifdef SYS_membarrier | |
cf5271ee MD |
60 | # define MEMBARRIER_EXPEDITED (1 << 0) |
61 | # define MEMBARRIER_DELAYED (1 << 1) | |
62 | # define MEMBARRIER_QUERY (1 << 16) | |
d4fc680a | 63 | # define membarrier(...) syscall(SYS_membarrier, __VA_ARGS__) |
fdf01eed | 64 | #else |
f0708810 MD |
65 | # undef RCU_MEMBARRIER |
66 | # define RCU_MB | |
fdf01eed MD |
67 | #endif |
68 | #endif | |
69 | ||
adcfce54 MD |
70 | /* |
71 | * This code section can only be included in LGPL 2.1 compatible source code. | |
72 | * See below for the function call wrappers which can be used in code meant to | |
73 | * be only linked with the Userspace RCU library. This comes with a small | |
74 | * performance degradation on the read-side due to the added function calls. | |
75 | * This is required to permit relinking with newer versions of the library. | |
76 | */ | |
77 | ||
78 | /* | |
79 | * The signal number used by the RCU library can be overridden with | |
02be5561 | 80 | * -DSIGRCU= when compiling the library. |
ddf7eefb | 81 | * Provide backward compatibility for liburcu 0.3.x SIGURCU. |
adcfce54 | 82 | */ |
ddf7eefb MD |
83 | #ifdef SIGURCU |
84 | #define SIGRCU SIGURCU | |
85 | #endif | |
86 | ||
02be5561 MD |
87 | #ifndef SIGRCU |
88 | #define SIGRCU SIGUSR1 | |
adcfce54 MD |
89 | #endif |
90 | ||
91 | /* | |
92 | * If a reader is really non-cooperative and refuses to commit its | |
02be5561 | 93 | * rcu_active_readers count to memory (there is no barrier in the reader |
adcfce54 MD |
94 | * per-se), kick it after a few loops waiting for it. |
95 | */ | |
96 | #define KICK_READER_LOOPS 10000 | |
97 | ||
bc6c15bb MD |
98 | /* |
99 | * Active attempts to check for reader Q.S. before calling futex(). | |
100 | */ | |
101 | #define RCU_QS_ACTIVE_ATTEMPTS 100 | |
102 | ||
7ac06cef MD |
103 | #ifdef DEBUG_RCU |
104 | #define rcu_assert(args...) assert(args) | |
105 | #else | |
106 | #define rcu_assert(args...) | |
107 | #endif | |
108 | ||
adcfce54 MD |
109 | #ifdef DEBUG_YIELD |
110 | #include <sched.h> | |
111 | #include <time.h> | |
112 | #include <pthread.h> | |
113 | #include <unistd.h> | |
114 | ||
115 | #define YIELD_READ (1 << 0) | |
116 | #define YIELD_WRITE (1 << 1) | |
117 | ||
b4ce1526 | 118 | /* |
fdf01eed | 119 | * Updates with RCU_SIGNAL are much slower. Account this in the delay. |
b4ce1526 | 120 | */ |
fdf01eed | 121 | #ifdef RCU_SIGNAL |
adcfce54 | 122 | /* maximum sleep delay, in us */ |
adcfce54 | 123 | #define MAX_SLEEP 30000 |
fdf01eed MD |
124 | #else |
125 | #define MAX_SLEEP 50 | |
adcfce54 MD |
126 | #endif |
127 | ||
128 | extern unsigned int yield_active; | |
129 | extern unsigned int __thread rand_yield; | |
130 | ||
131 | static inline void debug_yield_read(void) | |
132 | { | |
133 | if (yield_active & YIELD_READ) | |
134 | if (rand_r(&rand_yield) & 0x1) | |
135 | usleep(rand_r(&rand_yield) % MAX_SLEEP); | |
136 | } | |
137 | ||
138 | static inline void debug_yield_write(void) | |
139 | { | |
140 | if (yield_active & YIELD_WRITE) | |
141 | if (rand_r(&rand_yield) & 0x1) | |
142 | usleep(rand_r(&rand_yield) % MAX_SLEEP); | |
143 | } | |
144 | ||
145 | static inline void debug_yield_init(void) | |
146 | { | |
147 | rand_yield = time(NULL) ^ pthread_self(); | |
148 | } | |
149 | #else | |
150 | static inline void debug_yield_read(void) | |
151 | { | |
152 | } | |
153 | ||
154 | static inline void debug_yield_write(void) | |
155 | { | |
156 | } | |
157 | ||
158 | static inline void debug_yield_init(void) | |
159 | { | |
160 | ||
161 | } | |
162 | #endif | |
163 | ||
25cc6d18 MD |
164 | /* |
165 | * RCU memory barrier broadcast group. Currently, only broadcast to all process | |
166 | * threads is supported (group 0). | |
167 | * | |
168 | * Slave barriers are only guaranteed to be ordered wrt master barriers. | |
169 | * | |
170 | * The pair ordering is detailed as (O: ordered, X: not ordered) : | |
171 | * slave master | |
172 | * slave X O | |
173 | * master O O | |
174 | */ | |
175 | ||
176 | #define MB_GROUP_ALL 0 | |
177 | #define RCU_MB_GROUP MB_GROUP_ALL | |
178 | ||
fdf01eed MD |
179 | #ifdef RCU_MEMBARRIER |
180 | extern int has_sys_membarrier; | |
181 | ||
25cc6d18 | 182 | static inline void smp_mb_slave(int group) |
fdf01eed MD |
183 | { |
184 | if (likely(has_sys_membarrier)) | |
5481ddb3 | 185 | cmm_barrier(); |
fdf01eed | 186 | else |
5481ddb3 | 187 | cmm_smp_mb(); |
fdf01eed MD |
188 | } |
189 | #endif | |
190 | ||
02be5561 | 191 | #ifdef RCU_MB |
25cc6d18 | 192 | static inline void smp_mb_slave(int group) |
adcfce54 | 193 | { |
5481ddb3 | 194 | cmm_smp_mb(); |
adcfce54 | 195 | } |
fdf01eed MD |
196 | #endif |
197 | ||
198 | #ifdef RCU_SIGNAL | |
25cc6d18 | 199 | static inline void smp_mb_slave(int group) |
adcfce54 | 200 | { |
5481ddb3 | 201 | cmm_barrier(); |
adcfce54 MD |
202 | } |
203 | #endif | |
204 | ||
205 | /* | |
02be5561 MD |
206 | * The trick here is that RCU_GP_CTR_PHASE must be a multiple of 8 so we can use |
207 | * a full 8-bits, 16-bits or 32-bits bitmask for the lower order bits. | |
adcfce54 MD |
208 | */ |
209 | #define RCU_GP_COUNT (1UL << 0) | |
210 | /* Use the amount of bits equal to half of the architecture long size */ | |
27d65bc5 | 211 | #define RCU_GP_CTR_PHASE (1UL << (sizeof(unsigned long) << 2)) |
02be5561 | 212 | #define RCU_GP_CTR_NEST_MASK (RCU_GP_CTR_PHASE - 1) |
adcfce54 MD |
213 | |
214 | /* | |
215 | * Global quiescent period counter with low-order bits unused. | |
216 | * Using a int rather than a char to eliminate false register dependencies | |
217 | * causing stalls on some architectures. | |
218 | */ | |
27d65bc5 | 219 | extern unsigned long rcu_gp_ctr; |
adcfce54 | 220 | |
02be5561 | 221 | struct rcu_reader { |
bd1a5e15 | 222 | /* Data used by both reader and synchronize_rcu() */ |
27d65bc5 | 223 | unsigned long ctr; |
e3b0cef0 | 224 | char need_mb; |
bd1a5e15 | 225 | /* Data used for registry */ |
16aa9ee8 | 226 | struct cds_list_head node __attribute__((aligned(CAA_CACHE_LINE_SIZE))); |
bd1a5e15 | 227 | pthread_t tid; |
e3b0cef0 MD |
228 | }; |
229 | ||
02be5561 | 230 | extern struct rcu_reader __thread rcu_reader; |
adcfce54 | 231 | |
6d841bc2 | 232 | extern int32_t gp_futex; |
bc6c15bb MD |
233 | |
234 | /* | |
235 | * Wake-up waiting synchronize_rcu(). Called from many concurrent threads. | |
236 | */ | |
237 | static inline void wake_up_gp(void) | |
238 | { | |
ec4e58a3 MD |
239 | if (unlikely(uatomic_read(&gp_futex) == -1)) { |
240 | uatomic_set(&gp_futex, 0); | |
0854ccff | 241 | futex_async(&gp_futex, FUTEX_WAKE, 1, |
bc6c15bb MD |
242 | NULL, NULL, 0); |
243 | } | |
244 | } | |
245 | ||
e26fa029 | 246 | static inline int rcu_gp_ongoing(unsigned long *ctr) |
adcfce54 | 247 | { |
27d65bc5 | 248 | unsigned long v; |
adcfce54 | 249 | |
adcfce54 MD |
250 | /* |
251 | * Make sure both tests below are done on the same version of *value | |
252 | * to insure consistency. | |
253 | */ | |
6cf3827c | 254 | v = CMM_LOAD_SHARED(*ctr); |
adcfce54 | 255 | return (v & RCU_GP_CTR_NEST_MASK) && |
02be5561 | 256 | ((v ^ rcu_gp_ctr) & RCU_GP_CTR_PHASE); |
adcfce54 MD |
257 | } |
258 | ||
259 | static inline void _rcu_read_lock(void) | |
260 | { | |
27d65bc5 | 261 | unsigned long tmp; |
adcfce54 | 262 | |
5481ddb3 | 263 | cmm_barrier(); /* Ensure the compiler does not reorder us with mutex */ |
02be5561 MD |
264 | tmp = rcu_reader.ctr; |
265 | /* | |
266 | * rcu_gp_ctr is | |
267 | * RCU_GP_COUNT | (~RCU_GP_CTR_PHASE or RCU_GP_CTR_PHASE) | |
268 | */ | |
67ef1a2c | 269 | if (likely(!(tmp & RCU_GP_CTR_NEST_MASK))) { |
6cf3827c | 270 | _CMM_STORE_SHARED(rcu_reader.ctr, _CMM_LOAD_SHARED(rcu_gp_ctr)); |
67ef1a2c MD |
271 | /* |
272 | * Set active readers count for outermost nesting level before | |
25cc6d18 | 273 | * accessing the pointer. See smp_mb_master(). |
67ef1a2c | 274 | */ |
25cc6d18 | 275 | smp_mb_slave(RCU_MB_GROUP); |
67ef1a2c | 276 | } else { |
6cf3827c | 277 | _CMM_STORE_SHARED(rcu_reader.ctr, tmp + RCU_GP_COUNT); |
67ef1a2c | 278 | } |
adcfce54 MD |
279 | } |
280 | ||
281 | static inline void _rcu_read_unlock(void) | |
282 | { | |
27d65bc5 | 283 | unsigned long tmp; |
bc6c15bb | 284 | |
02be5561 | 285 | tmp = rcu_reader.ctr; |
adcfce54 MD |
286 | /* |
287 | * Finish using rcu before decrementing the pointer. | |
25cc6d18 | 288 | * See smp_mb_master(). |
adcfce54 | 289 | */ |
bc6c15bb | 290 | if (likely((tmp & RCU_GP_CTR_NEST_MASK) == RCU_GP_COUNT)) { |
25cc6d18 | 291 | smp_mb_slave(RCU_MB_GROUP); |
6cf3827c | 292 | _CMM_STORE_SHARED(rcu_reader.ctr, rcu_reader.ctr - RCU_GP_COUNT); |
02be5561 | 293 | /* write rcu_reader.ctr before read futex */ |
25cc6d18 | 294 | smp_mb_slave(RCU_MB_GROUP); |
bc6c15bb MD |
295 | wake_up_gp(); |
296 | } else { | |
6cf3827c | 297 | _CMM_STORE_SHARED(rcu_reader.ctr, rcu_reader.ctr - RCU_GP_COUNT); |
bc6c15bb | 298 | } |
5481ddb3 | 299 | cmm_barrier(); /* Ensure the compiler does not reorder us with mutex */ |
adcfce54 MD |
300 | } |
301 | ||
ad918eeb | 302 | #ifdef __cplusplus |
36bc70a8 MD |
303 | } |
304 | #endif | |
305 | ||
adcfce54 | 306 | #endif /* _URCU_STATIC_H */ |