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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 | * |
a5a9f428 PM |
9 | * TO BE INCLUDED ONLY IN CODE THAT IS TO BE RECOMPILED ON EACH LIBURCU |
10 | * RELEASE. See urcu.h for linking 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> |
bd252a04 | 43 | #include <urcu/tls-compat.h> |
bc6c15bb | 44 | |
36bc70a8 MD |
45 | #ifdef __cplusplus |
46 | extern "C" { | |
47 | #endif | |
48 | ||
65f1e634 | 49 | /* Default is RCU_MEMBARRIER */ |
fdf01eed | 50 | #if !defined(RCU_MEMBARRIER) && !defined(RCU_MB) && !defined(RCU_SIGNAL) |
65f1e634 MD |
51 | #define RCU_MEMBARRIER |
52 | #endif | |
53 | ||
54 | /* | |
55 | * RCU_MEMBARRIER is only possibly available on Linux. Fallback to RCU_MB | |
56 | * otherwise. | |
57 | */ | |
58 | #if !defined(__linux__) && defined(RCU_MEMBARRIER) | |
59 | #undef RCU_MEMBARRIER | |
60 | #define RCU_MB | |
fdf01eed MD |
61 | #endif |
62 | ||
63 | #ifdef RCU_MEMBARRIER | |
4906d398 | 64 | #include <syscall.h> |
fdf01eed MD |
65 | |
66 | /* If the headers do not support SYS_membarrier, statically use RCU_MB */ | |
67 | #ifdef SYS_membarrier | |
cf5271ee MD |
68 | # define MEMBARRIER_EXPEDITED (1 << 0) |
69 | # define MEMBARRIER_DELAYED (1 << 1) | |
70 | # define MEMBARRIER_QUERY (1 << 16) | |
d4fc680a | 71 | # define membarrier(...) syscall(SYS_membarrier, __VA_ARGS__) |
fdf01eed | 72 | #else |
f0708810 MD |
73 | # undef RCU_MEMBARRIER |
74 | # define RCU_MB | |
fdf01eed MD |
75 | #endif |
76 | #endif | |
77 | ||
adcfce54 MD |
78 | /* |
79 | * This code section can only be included in LGPL 2.1 compatible source code. | |
80 | * See below for the function call wrappers which can be used in code meant to | |
81 | * be only linked with the Userspace RCU library. This comes with a small | |
82 | * performance degradation on the read-side due to the added function calls. | |
83 | * This is required to permit relinking with newer versions of the library. | |
84 | */ | |
85 | ||
86 | /* | |
87 | * The signal number used by the RCU library can be overridden with | |
02be5561 | 88 | * -DSIGRCU= when compiling the library. |
ddf7eefb | 89 | * Provide backward compatibility for liburcu 0.3.x SIGURCU. |
adcfce54 | 90 | */ |
ddf7eefb MD |
91 | #ifdef SIGURCU |
92 | #define SIGRCU SIGURCU | |
93 | #endif | |
94 | ||
02be5561 MD |
95 | #ifndef SIGRCU |
96 | #define SIGRCU SIGUSR1 | |
adcfce54 MD |
97 | #endif |
98 | ||
fd189fa5 MD |
99 | enum rcu_state { |
100 | RCU_READER_ACTIVE_CURRENT, | |
101 | RCU_READER_ACTIVE_OLD, | |
102 | RCU_READER_INACTIVE, | |
103 | }; | |
104 | ||
7ac06cef MD |
105 | #ifdef DEBUG_RCU |
106 | #define rcu_assert(args...) assert(args) | |
107 | #else | |
108 | #define rcu_assert(args...) | |
109 | #endif | |
110 | ||
adcfce54 MD |
111 | #ifdef DEBUG_YIELD |
112 | #include <sched.h> | |
113 | #include <time.h> | |
114 | #include <pthread.h> | |
115 | #include <unistd.h> | |
116 | ||
1de4df4b MD |
117 | #define RCU_YIELD_READ (1 << 0) |
118 | #define RCU_YIELD_WRITE (1 << 1) | |
adcfce54 | 119 | |
b4ce1526 | 120 | /* |
fdf01eed | 121 | * Updates with RCU_SIGNAL are much slower. Account this in the delay. |
b4ce1526 | 122 | */ |
fdf01eed | 123 | #ifdef RCU_SIGNAL |
adcfce54 | 124 | /* maximum sleep delay, in us */ |
adcfce54 | 125 | #define MAX_SLEEP 30000 |
fdf01eed MD |
126 | #else |
127 | #define MAX_SLEEP 50 | |
adcfce54 MD |
128 | #endif |
129 | ||
1de4df4b MD |
130 | extern unsigned int rcu_yield_active; |
131 | extern DECLARE_URCU_TLS(unsigned int, rcu_rand_yield); | |
adcfce54 | 132 | |
1de4df4b | 133 | static inline void rcu_debug_yield_read(void) |
adcfce54 | 134 | { |
1de4df4b MD |
135 | if (rcu_yield_active & RCU_YIELD_READ) |
136 | if (rand_r(&URCU_TLS(rcu_rand_yield)) & 0x1) | |
137 | usleep(rand_r(&URCU_TLS(rcu_rand_yield)) % MAX_SLEEP); | |
adcfce54 MD |
138 | } |
139 | ||
1de4df4b | 140 | static inline void rcu_debug_yield_write(void) |
adcfce54 | 141 | { |
1de4df4b MD |
142 | if (rcu_yield_active & RCU_YIELD_WRITE) |
143 | if (rand_r(&URCU_TLS(rcu_rand_yield)) & 0x1) | |
144 | usleep(rand_r(&URCU_TLS(rcu_rand_yield)) % MAX_SLEEP); | |
adcfce54 MD |
145 | } |
146 | ||
1de4df4b | 147 | static inline void rcu_debug_yield_init(void) |
adcfce54 | 148 | { |
1de4df4b | 149 | URCU_TLS(rcu_rand_yield) = time(NULL) ^ (unsigned long) pthread_self(); |
adcfce54 MD |
150 | } |
151 | #else | |
1de4df4b | 152 | static inline void rcu_debug_yield_read(void) |
adcfce54 MD |
153 | { |
154 | } | |
155 | ||
1de4df4b | 156 | static inline void rcu_debug_yield_write(void) |
adcfce54 MD |
157 | { |
158 | } | |
159 | ||
1de4df4b | 160 | static inline void rcu_debug_yield_init(void) |
adcfce54 MD |
161 | { |
162 | ||
163 | } | |
164 | #endif | |
165 | ||
25cc6d18 MD |
166 | /* |
167 | * RCU memory barrier broadcast group. Currently, only broadcast to all process | |
168 | * threads is supported (group 0). | |
169 | * | |
170 | * Slave barriers are only guaranteed to be ordered wrt master barriers. | |
171 | * | |
172 | * The pair ordering is detailed as (O: ordered, X: not ordered) : | |
173 | * slave master | |
174 | * slave X O | |
175 | * master O O | |
176 | */ | |
177 | ||
178 | #define MB_GROUP_ALL 0 | |
179 | #define RCU_MB_GROUP MB_GROUP_ALL | |
180 | ||
fdf01eed | 181 | #ifdef RCU_MEMBARRIER |
1de4df4b | 182 | extern int rcu_has_sys_membarrier; |
fdf01eed | 183 | |
25cc6d18 | 184 | static inline void smp_mb_slave(int group) |
fdf01eed | 185 | { |
1de4df4b | 186 | if (caa_likely(rcu_has_sys_membarrier)) |
5481ddb3 | 187 | cmm_barrier(); |
fdf01eed | 188 | else |
5481ddb3 | 189 | cmm_smp_mb(); |
fdf01eed MD |
190 | } |
191 | #endif | |
192 | ||
02be5561 | 193 | #ifdef RCU_MB |
25cc6d18 | 194 | static inline void smp_mb_slave(int group) |
adcfce54 | 195 | { |
5481ddb3 | 196 | cmm_smp_mb(); |
adcfce54 | 197 | } |
fdf01eed MD |
198 | #endif |
199 | ||
200 | #ifdef RCU_SIGNAL | |
25cc6d18 | 201 | static inline void smp_mb_slave(int group) |
adcfce54 | 202 | { |
5481ddb3 | 203 | cmm_barrier(); |
adcfce54 MD |
204 | } |
205 | #endif | |
206 | ||
207 | /* | |
02be5561 MD |
208 | * The trick here is that RCU_GP_CTR_PHASE must be a multiple of 8 so we can use |
209 | * a full 8-bits, 16-bits or 32-bits bitmask for the lower order bits. | |
adcfce54 MD |
210 | */ |
211 | #define RCU_GP_COUNT (1UL << 0) | |
212 | /* Use the amount of bits equal to half of the architecture long size */ | |
27d65bc5 | 213 | #define RCU_GP_CTR_PHASE (1UL << (sizeof(unsigned long) << 2)) |
02be5561 | 214 | #define RCU_GP_CTR_NEST_MASK (RCU_GP_CTR_PHASE - 1) |
adcfce54 MD |
215 | |
216 | /* | |
217 | * Global quiescent period counter with low-order bits unused. | |
218 | * Using a int rather than a char to eliminate false register dependencies | |
219 | * causing stalls on some architectures. | |
220 | */ | |
27d65bc5 | 221 | extern unsigned long rcu_gp_ctr; |
adcfce54 | 222 | |
02be5561 | 223 | struct rcu_reader { |
bd1a5e15 | 224 | /* Data used by both reader and synchronize_rcu() */ |
27d65bc5 | 225 | unsigned long ctr; |
e3b0cef0 | 226 | char need_mb; |
bd1a5e15 | 227 | /* Data used for registry */ |
16aa9ee8 | 228 | struct cds_list_head node __attribute__((aligned(CAA_CACHE_LINE_SIZE))); |
bd1a5e15 | 229 | pthread_t tid; |
e3b0cef0 MD |
230 | }; |
231 | ||
bd252a04 | 232 | extern DECLARE_URCU_TLS(struct rcu_reader, rcu_reader); |
adcfce54 | 233 | |
1de4df4b | 234 | extern int32_t rcu_gp_futex; |
bc6c15bb MD |
235 | |
236 | /* | |
237 | * Wake-up waiting synchronize_rcu(). Called from many concurrent threads. | |
238 | */ | |
239 | static inline void wake_up_gp(void) | |
240 | { | |
1de4df4b MD |
241 | if (caa_unlikely(uatomic_read(&rcu_gp_futex) == -1)) { |
242 | uatomic_set(&rcu_gp_futex, 0); | |
243 | futex_async(&rcu_gp_futex, FUTEX_WAKE, 1, | |
bc6c15bb MD |
244 | NULL, NULL, 0); |
245 | } | |
246 | } | |
247 | ||
fd189fa5 | 248 | static inline enum rcu_state rcu_reader_state(unsigned long *ctr) |
adcfce54 | 249 | { |
27d65bc5 | 250 | unsigned long v; |
adcfce54 | 251 | |
adcfce54 MD |
252 | /* |
253 | * Make sure both tests below are done on the same version of *value | |
254 | * to insure consistency. | |
255 | */ | |
6cf3827c | 256 | v = CMM_LOAD_SHARED(*ctr); |
fd189fa5 MD |
257 | if (!(v & RCU_GP_CTR_NEST_MASK)) |
258 | return RCU_READER_INACTIVE; | |
259 | if (!((v ^ rcu_gp_ctr) & RCU_GP_CTR_PHASE)) | |
260 | return RCU_READER_ACTIVE_CURRENT; | |
261 | return RCU_READER_ACTIVE_OLD; | |
adcfce54 MD |
262 | } |
263 | ||
a5a9f428 PM |
264 | /* |
265 | * Helper for _rcu_read_lock(). The format of rcu_gp_ctr (as well as | |
266 | * the per-thread rcu_reader.ctr) has the upper bits containing a count of | |
267 | * _rcu_read_lock() nesting, and a lower-order bit that contains either zero | |
268 | * or RCU_GP_CTR_PHASE. The smp_mb_slave() ensures that the accesses in | |
269 | * _rcu_read_lock() happen before the subsequent read-side critical section. | |
270 | */ | |
271 | static inline void _rcu_read_lock_update(unsigned long tmp) | |
adcfce54 | 272 | { |
a0b7f7ea | 273 | if (caa_likely(!(tmp & RCU_GP_CTR_NEST_MASK))) { |
bd252a04 | 274 | _CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, _CMM_LOAD_SHARED(rcu_gp_ctr)); |
25cc6d18 | 275 | smp_mb_slave(RCU_MB_GROUP); |
a5a9f428 | 276 | } else |
bd252a04 | 277 | _CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, tmp + RCU_GP_COUNT); |
adcfce54 MD |
278 | } |
279 | ||
a5a9f428 PM |
280 | /* |
281 | * Enter an RCU read-side critical section. | |
282 | * | |
283 | * The first cmm_barrier() call ensures that the compiler does not reorder | |
284 | * the body of _rcu_read_lock() with a mutex. | |
285 | * | |
286 | * This function and its helper are both less than 10 lines long. The | |
287 | * intent is that this function meets the 10-line criterion in LGPL, | |
288 | * allowing this function to be invoked directly from non-LGPL code. | |
289 | */ | |
290 | static inline void _rcu_read_lock(void) | |
adcfce54 | 291 | { |
27d65bc5 | 292 | unsigned long tmp; |
bc6c15bb | 293 | |
a5a9f428 | 294 | cmm_barrier(); |
bd252a04 | 295 | tmp = URCU_TLS(rcu_reader).ctr; |
a5a9f428 PM |
296 | _rcu_read_lock_update(tmp); |
297 | } | |
298 | ||
299 | /* | |
300 | * This is a helper function for _rcu_read_unlock(). | |
301 | * | |
302 | * The first smp_mb_slave() call ensures that the critical section is | |
303 | * seen to precede the store to rcu_reader.ctr. | |
304 | * The second smp_mb_slave() call ensures that we write to rcu_reader.ctr | |
305 | * before reading the update-side futex. | |
306 | */ | |
307 | static inline void _rcu_read_unlock_update_and_wakeup(unsigned long tmp) | |
308 | { | |
a0b7f7ea | 309 | if (caa_likely((tmp & RCU_GP_CTR_NEST_MASK) == RCU_GP_COUNT)) { |
25cc6d18 | 310 | smp_mb_slave(RCU_MB_GROUP); |
bd252a04 | 311 | _CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, URCU_TLS(rcu_reader).ctr - RCU_GP_COUNT); |
25cc6d18 | 312 | smp_mb_slave(RCU_MB_GROUP); |
bc6c15bb | 313 | wake_up_gp(); |
a5a9f428 | 314 | } else |
bd252a04 | 315 | _CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, URCU_TLS(rcu_reader).ctr - RCU_GP_COUNT); |
a5a9f428 PM |
316 | } |
317 | ||
318 | /* | |
319 | * Exit an RCU read-side crtical section. Both this function and its | |
320 | * helper are smaller than 10 lines of code, and are intended to be | |
321 | * usable by non-LGPL code, as called out in LGPL. | |
322 | */ | |
323 | static inline void _rcu_read_unlock(void) | |
324 | { | |
325 | unsigned long tmp; | |
326 | ||
327 | tmp = URCU_TLS(rcu_reader).ctr; | |
328 | _rcu_read_unlock_update_and_wakeup(tmp); | |
5481ddb3 | 329 | cmm_barrier(); /* Ensure the compiler does not reorder us with mutex */ |
adcfce54 MD |
330 | } |
331 | ||
ad918eeb | 332 | #ifdef __cplusplus |
36bc70a8 MD |
333 | } |
334 | #endif | |
335 | ||
adcfce54 | 336 | #endif /* _URCU_STATIC_H */ |