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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 | 34 | #include <unistd.h> |
6d841bc2 | 35 | #include <stdint.h> |
adcfce54 | 36 | |
ec4e58a3 MD |
37 | #include <urcu/compiler.h> |
38 | #include <urcu/arch.h> | |
7e30abe3 | 39 | #include <urcu/system.h> |
a2e7bf9c | 40 | #include <urcu/uatomic.h> |
e3b0cef0 | 41 | #include <urcu/list.h> |
41849996 | 42 | #include <urcu/futex.h> |
bc6c15bb | 43 | |
36bc70a8 MD |
44 | #ifdef __cplusplus |
45 | extern "C" { | |
46 | #endif | |
47 | ||
65f1e634 | 48 | /* Default is RCU_MEMBARRIER */ |
fdf01eed | 49 | #if !defined(RCU_MEMBARRIER) && !defined(RCU_MB) && !defined(RCU_SIGNAL) |
65f1e634 MD |
50 | #define RCU_MEMBARRIER |
51 | #endif | |
52 | ||
53 | /* | |
54 | * RCU_MEMBARRIER is only possibly available on Linux. Fallback to RCU_MB | |
55 | * otherwise. | |
56 | */ | |
57 | #if !defined(__linux__) && defined(RCU_MEMBARRIER) | |
58 | #undef RCU_MEMBARRIER | |
59 | #define RCU_MB | |
fdf01eed MD |
60 | #endif |
61 | ||
62 | #ifdef RCU_MEMBARRIER | |
4906d398 | 63 | #include <syscall.h> |
fdf01eed MD |
64 | |
65 | /* If the headers do not support SYS_membarrier, statically use RCU_MB */ | |
66 | #ifdef SYS_membarrier | |
cf5271ee MD |
67 | # define MEMBARRIER_EXPEDITED (1 << 0) |
68 | # define MEMBARRIER_DELAYED (1 << 1) | |
69 | # define MEMBARRIER_QUERY (1 << 16) | |
d4fc680a | 70 | # define membarrier(...) syscall(SYS_membarrier, __VA_ARGS__) |
fdf01eed | 71 | #else |
f0708810 MD |
72 | # undef RCU_MEMBARRIER |
73 | # define RCU_MB | |
fdf01eed MD |
74 | #endif |
75 | #endif | |
76 | ||
adcfce54 MD |
77 | /* |
78 | * This code section can only be included in LGPL 2.1 compatible source code. | |
79 | * See below for the function call wrappers which can be used in code meant to | |
80 | * be only linked with the Userspace RCU library. This comes with a small | |
81 | * performance degradation on the read-side due to the added function calls. | |
82 | * This is required to permit relinking with newer versions of the library. | |
83 | */ | |
84 | ||
85 | /* | |
86 | * The signal number used by the RCU library can be overridden with | |
02be5561 | 87 | * -DSIGRCU= when compiling the library. |
ddf7eefb | 88 | * Provide backward compatibility for liburcu 0.3.x SIGURCU. |
adcfce54 | 89 | */ |
ddf7eefb MD |
90 | #ifdef SIGURCU |
91 | #define SIGRCU SIGURCU | |
92 | #endif | |
93 | ||
02be5561 MD |
94 | #ifndef SIGRCU |
95 | #define SIGRCU SIGUSR1 | |
adcfce54 MD |
96 | #endif |
97 | ||
7ac06cef MD |
98 | #ifdef DEBUG_RCU |
99 | #define rcu_assert(args...) assert(args) | |
100 | #else | |
101 | #define rcu_assert(args...) | |
102 | #endif | |
103 | ||
adcfce54 MD |
104 | #ifdef DEBUG_YIELD |
105 | #include <sched.h> | |
106 | #include <time.h> | |
107 | #include <pthread.h> | |
108 | #include <unistd.h> | |
109 | ||
110 | #define YIELD_READ (1 << 0) | |
111 | #define YIELD_WRITE (1 << 1) | |
112 | ||
b4ce1526 | 113 | /* |
fdf01eed | 114 | * Updates with RCU_SIGNAL are much slower. Account this in the delay. |
b4ce1526 | 115 | */ |
fdf01eed | 116 | #ifdef RCU_SIGNAL |
adcfce54 | 117 | /* maximum sleep delay, in us */ |
adcfce54 | 118 | #define MAX_SLEEP 30000 |
fdf01eed MD |
119 | #else |
120 | #define MAX_SLEEP 50 | |
adcfce54 MD |
121 | #endif |
122 | ||
123 | extern unsigned int yield_active; | |
124 | extern unsigned int __thread rand_yield; | |
125 | ||
126 | static inline void debug_yield_read(void) | |
127 | { | |
128 | if (yield_active & YIELD_READ) | |
129 | if (rand_r(&rand_yield) & 0x1) | |
130 | usleep(rand_r(&rand_yield) % MAX_SLEEP); | |
131 | } | |
132 | ||
133 | static inline void debug_yield_write(void) | |
134 | { | |
135 | if (yield_active & YIELD_WRITE) | |
136 | if (rand_r(&rand_yield) & 0x1) | |
137 | usleep(rand_r(&rand_yield) % MAX_SLEEP); | |
138 | } | |
139 | ||
140 | static inline void debug_yield_init(void) | |
141 | { | |
8ddd7970 | 142 | rand_yield = time(NULL) ^ (unsigned long) pthread_self(); |
adcfce54 MD |
143 | } |
144 | #else | |
145 | static inline void debug_yield_read(void) | |
146 | { | |
147 | } | |
148 | ||
149 | static inline void debug_yield_write(void) | |
150 | { | |
151 | } | |
152 | ||
153 | static inline void debug_yield_init(void) | |
154 | { | |
155 | ||
156 | } | |
157 | #endif | |
158 | ||
25cc6d18 MD |
159 | /* |
160 | * RCU memory barrier broadcast group. Currently, only broadcast to all process | |
161 | * threads is supported (group 0). | |
162 | * | |
163 | * Slave barriers are only guaranteed to be ordered wrt master barriers. | |
164 | * | |
165 | * The pair ordering is detailed as (O: ordered, X: not ordered) : | |
166 | * slave master | |
167 | * slave X O | |
168 | * master O O | |
169 | */ | |
170 | ||
171 | #define MB_GROUP_ALL 0 | |
172 | #define RCU_MB_GROUP MB_GROUP_ALL | |
173 | ||
fdf01eed MD |
174 | #ifdef RCU_MEMBARRIER |
175 | extern int has_sys_membarrier; | |
176 | ||
25cc6d18 | 177 | static inline void smp_mb_slave(int group) |
fdf01eed | 178 | { |
a0b7f7ea | 179 | if (caa_likely(has_sys_membarrier)) |
5481ddb3 | 180 | cmm_barrier(); |
fdf01eed | 181 | else |
5481ddb3 | 182 | cmm_smp_mb(); |
fdf01eed MD |
183 | } |
184 | #endif | |
185 | ||
02be5561 | 186 | #ifdef RCU_MB |
25cc6d18 | 187 | static inline void smp_mb_slave(int group) |
adcfce54 | 188 | { |
5481ddb3 | 189 | cmm_smp_mb(); |
adcfce54 | 190 | } |
fdf01eed MD |
191 | #endif |
192 | ||
193 | #ifdef RCU_SIGNAL | |
25cc6d18 | 194 | static inline void smp_mb_slave(int group) |
adcfce54 | 195 | { |
5481ddb3 | 196 | cmm_barrier(); |
adcfce54 MD |
197 | } |
198 | #endif | |
199 | ||
200 | /* | |
02be5561 MD |
201 | * The trick here is that RCU_GP_CTR_PHASE must be a multiple of 8 so we can use |
202 | * a full 8-bits, 16-bits or 32-bits bitmask for the lower order bits. | |
adcfce54 MD |
203 | */ |
204 | #define RCU_GP_COUNT (1UL << 0) | |
205 | /* Use the amount of bits equal to half of the architecture long size */ | |
27d65bc5 | 206 | #define RCU_GP_CTR_PHASE (1UL << (sizeof(unsigned long) << 2)) |
02be5561 | 207 | #define RCU_GP_CTR_NEST_MASK (RCU_GP_CTR_PHASE - 1) |
adcfce54 MD |
208 | |
209 | /* | |
210 | * Global quiescent period counter with low-order bits unused. | |
211 | * Using a int rather than a char to eliminate false register dependencies | |
212 | * causing stalls on some architectures. | |
213 | */ | |
27d65bc5 | 214 | extern unsigned long rcu_gp_ctr; |
adcfce54 | 215 | |
02be5561 | 216 | struct rcu_reader { |
bd1a5e15 | 217 | /* Data used by both reader and synchronize_rcu() */ |
27d65bc5 | 218 | unsigned long ctr; |
e3b0cef0 | 219 | char need_mb; |
bd1a5e15 | 220 | /* Data used for registry */ |
16aa9ee8 | 221 | struct cds_list_head node __attribute__((aligned(CAA_CACHE_LINE_SIZE))); |
bd1a5e15 | 222 | pthread_t tid; |
e3b0cef0 MD |
223 | }; |
224 | ||
02be5561 | 225 | extern struct rcu_reader __thread rcu_reader; |
adcfce54 | 226 | |
6d841bc2 | 227 | extern int32_t gp_futex; |
bc6c15bb MD |
228 | |
229 | /* | |
230 | * Wake-up waiting synchronize_rcu(). Called from many concurrent threads. | |
231 | */ | |
232 | static inline void wake_up_gp(void) | |
233 | { | |
a0b7f7ea | 234 | if (caa_unlikely(uatomic_read(&gp_futex) == -1)) { |
ec4e58a3 | 235 | uatomic_set(&gp_futex, 0); |
0854ccff | 236 | futex_async(&gp_futex, FUTEX_WAKE, 1, |
bc6c15bb MD |
237 | NULL, NULL, 0); |
238 | } | |
239 | } | |
240 | ||
e26fa029 | 241 | static inline int rcu_gp_ongoing(unsigned long *ctr) |
adcfce54 | 242 | { |
27d65bc5 | 243 | unsigned long v; |
adcfce54 | 244 | |
adcfce54 MD |
245 | /* |
246 | * Make sure both tests below are done on the same version of *value | |
247 | * to insure consistency. | |
248 | */ | |
6cf3827c | 249 | v = CMM_LOAD_SHARED(*ctr); |
adcfce54 | 250 | return (v & RCU_GP_CTR_NEST_MASK) && |
02be5561 | 251 | ((v ^ rcu_gp_ctr) & RCU_GP_CTR_PHASE); |
adcfce54 MD |
252 | } |
253 | ||
254 | static inline void _rcu_read_lock(void) | |
255 | { | |
27d65bc5 | 256 | unsigned long tmp; |
adcfce54 | 257 | |
5481ddb3 | 258 | cmm_barrier(); /* Ensure the compiler does not reorder us with mutex */ |
02be5561 MD |
259 | tmp = rcu_reader.ctr; |
260 | /* | |
261 | * rcu_gp_ctr is | |
262 | * RCU_GP_COUNT | (~RCU_GP_CTR_PHASE or RCU_GP_CTR_PHASE) | |
263 | */ | |
a0b7f7ea | 264 | if (caa_likely(!(tmp & RCU_GP_CTR_NEST_MASK))) { |
6cf3827c | 265 | _CMM_STORE_SHARED(rcu_reader.ctr, _CMM_LOAD_SHARED(rcu_gp_ctr)); |
67ef1a2c MD |
266 | /* |
267 | * Set active readers count for outermost nesting level before | |
25cc6d18 | 268 | * accessing the pointer. See smp_mb_master(). |
67ef1a2c | 269 | */ |
25cc6d18 | 270 | smp_mb_slave(RCU_MB_GROUP); |
67ef1a2c | 271 | } else { |
6cf3827c | 272 | _CMM_STORE_SHARED(rcu_reader.ctr, tmp + RCU_GP_COUNT); |
67ef1a2c | 273 | } |
adcfce54 MD |
274 | } |
275 | ||
276 | static inline void _rcu_read_unlock(void) | |
277 | { | |
27d65bc5 | 278 | unsigned long tmp; |
bc6c15bb | 279 | |
02be5561 | 280 | tmp = rcu_reader.ctr; |
adcfce54 MD |
281 | /* |
282 | * Finish using rcu before decrementing the pointer. | |
25cc6d18 | 283 | * See smp_mb_master(). |
adcfce54 | 284 | */ |
a0b7f7ea | 285 | if (caa_likely((tmp & RCU_GP_CTR_NEST_MASK) == RCU_GP_COUNT)) { |
25cc6d18 | 286 | smp_mb_slave(RCU_MB_GROUP); |
6cf3827c | 287 | _CMM_STORE_SHARED(rcu_reader.ctr, rcu_reader.ctr - RCU_GP_COUNT); |
02be5561 | 288 | /* write rcu_reader.ctr before read futex */ |
25cc6d18 | 289 | smp_mb_slave(RCU_MB_GROUP); |
bc6c15bb MD |
290 | wake_up_gp(); |
291 | } else { | |
6cf3827c | 292 | _CMM_STORE_SHARED(rcu_reader.ctr, rcu_reader.ctr - RCU_GP_COUNT); |
bc6c15bb | 293 | } |
5481ddb3 | 294 | cmm_barrier(); /* Ensure the compiler does not reorder us with mutex */ |
adcfce54 MD |
295 | } |
296 | ||
ad918eeb | 297 | #ifdef __cplusplus |
36bc70a8 MD |
298 | } |
299 | #endif | |
300 | ||
adcfce54 | 301 | #endif /* _URCU_STATIC_H */ |