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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 | ||
7ac06cef MD |
99 | #ifdef DEBUG_RCU |
100 | #define rcu_assert(args...) assert(args) | |
101 | #else | |
102 | #define rcu_assert(args...) | |
103 | #endif | |
104 | ||
adcfce54 MD |
105 | #ifdef DEBUG_YIELD |
106 | #include <sched.h> | |
107 | #include <time.h> | |
108 | #include <pthread.h> | |
109 | #include <unistd.h> | |
110 | ||
111 | #define YIELD_READ (1 << 0) | |
112 | #define YIELD_WRITE (1 << 1) | |
113 | ||
b4ce1526 | 114 | /* |
fdf01eed | 115 | * Updates with RCU_SIGNAL are much slower. Account this in the delay. |
b4ce1526 | 116 | */ |
fdf01eed | 117 | #ifdef RCU_SIGNAL |
adcfce54 | 118 | /* maximum sleep delay, in us */ |
adcfce54 | 119 | #define MAX_SLEEP 30000 |
fdf01eed MD |
120 | #else |
121 | #define MAX_SLEEP 50 | |
adcfce54 MD |
122 | #endif |
123 | ||
124 | extern unsigned int yield_active; | |
bd252a04 | 125 | extern DECLARE_URCU_TLS(unsigned int, rand_yield); |
adcfce54 MD |
126 | |
127 | static inline void debug_yield_read(void) | |
128 | { | |
129 | if (yield_active & YIELD_READ) | |
bd252a04 MD |
130 | if (rand_r(&URCU_TLS(rand_yield)) & 0x1) |
131 | usleep(rand_r(&URCU_TLS(rand_yield)) % MAX_SLEEP); | |
adcfce54 MD |
132 | } |
133 | ||
134 | static inline void debug_yield_write(void) | |
135 | { | |
136 | if (yield_active & YIELD_WRITE) | |
bd252a04 MD |
137 | if (rand_r(&URCU_TLS(rand_yield)) & 0x1) |
138 | usleep(rand_r(&URCU_TLS(rand_yield)) % MAX_SLEEP); | |
adcfce54 MD |
139 | } |
140 | ||
141 | static inline void debug_yield_init(void) | |
142 | { | |
bd252a04 | 143 | URCU_TLS(rand_yield) = time(NULL) ^ (unsigned long) pthread_self(); |
adcfce54 MD |
144 | } |
145 | #else | |
146 | static inline void debug_yield_read(void) | |
147 | { | |
148 | } | |
149 | ||
150 | static inline void debug_yield_write(void) | |
151 | { | |
152 | } | |
153 | ||
154 | static inline void debug_yield_init(void) | |
155 | { | |
156 | ||
157 | } | |
158 | #endif | |
159 | ||
25cc6d18 MD |
160 | /* |
161 | * RCU memory barrier broadcast group. Currently, only broadcast to all process | |
162 | * threads is supported (group 0). | |
163 | * | |
164 | * Slave barriers are only guaranteed to be ordered wrt master barriers. | |
165 | * | |
166 | * The pair ordering is detailed as (O: ordered, X: not ordered) : | |
167 | * slave master | |
168 | * slave X O | |
169 | * master O O | |
170 | */ | |
171 | ||
172 | #define MB_GROUP_ALL 0 | |
173 | #define RCU_MB_GROUP MB_GROUP_ALL | |
174 | ||
fdf01eed MD |
175 | #ifdef RCU_MEMBARRIER |
176 | extern int has_sys_membarrier; | |
177 | ||
25cc6d18 | 178 | static inline void smp_mb_slave(int group) |
fdf01eed | 179 | { |
a0b7f7ea | 180 | if (caa_likely(has_sys_membarrier)) |
5481ddb3 | 181 | cmm_barrier(); |
fdf01eed | 182 | else |
5481ddb3 | 183 | cmm_smp_mb(); |
fdf01eed MD |
184 | } |
185 | #endif | |
186 | ||
02be5561 | 187 | #ifdef RCU_MB |
25cc6d18 | 188 | static inline void smp_mb_slave(int group) |
adcfce54 | 189 | { |
5481ddb3 | 190 | cmm_smp_mb(); |
adcfce54 | 191 | } |
fdf01eed MD |
192 | #endif |
193 | ||
194 | #ifdef RCU_SIGNAL | |
25cc6d18 | 195 | static inline void smp_mb_slave(int group) |
adcfce54 | 196 | { |
5481ddb3 | 197 | cmm_barrier(); |
adcfce54 MD |
198 | } |
199 | #endif | |
200 | ||
201 | /* | |
02be5561 MD |
202 | * The trick here is that RCU_GP_CTR_PHASE must be a multiple of 8 so we can use |
203 | * a full 8-bits, 16-bits or 32-bits bitmask for the lower order bits. | |
adcfce54 MD |
204 | */ |
205 | #define RCU_GP_COUNT (1UL << 0) | |
206 | /* Use the amount of bits equal to half of the architecture long size */ | |
27d65bc5 | 207 | #define RCU_GP_CTR_PHASE (1UL << (sizeof(unsigned long) << 2)) |
02be5561 | 208 | #define RCU_GP_CTR_NEST_MASK (RCU_GP_CTR_PHASE - 1) |
adcfce54 MD |
209 | |
210 | /* | |
211 | * Global quiescent period counter with low-order bits unused. | |
212 | * Using a int rather than a char to eliminate false register dependencies | |
213 | * causing stalls on some architectures. | |
214 | */ | |
27d65bc5 | 215 | extern unsigned long rcu_gp_ctr; |
adcfce54 | 216 | |
02be5561 | 217 | struct rcu_reader { |
bd1a5e15 | 218 | /* Data used by both reader and synchronize_rcu() */ |
27d65bc5 | 219 | unsigned long ctr; |
e3b0cef0 | 220 | char need_mb; |
bd1a5e15 | 221 | /* Data used for registry */ |
16aa9ee8 | 222 | struct cds_list_head node __attribute__((aligned(CAA_CACHE_LINE_SIZE))); |
bd1a5e15 | 223 | pthread_t tid; |
e3b0cef0 MD |
224 | }; |
225 | ||
bd252a04 | 226 | extern DECLARE_URCU_TLS(struct rcu_reader, rcu_reader); |
adcfce54 | 227 | |
6d841bc2 | 228 | extern int32_t gp_futex; |
bc6c15bb MD |
229 | |
230 | /* | |
231 | * Wake-up waiting synchronize_rcu(). Called from many concurrent threads. | |
232 | */ | |
233 | static inline void wake_up_gp(void) | |
234 | { | |
a0b7f7ea | 235 | if (caa_unlikely(uatomic_read(&gp_futex) == -1)) { |
ec4e58a3 | 236 | uatomic_set(&gp_futex, 0); |
0854ccff | 237 | futex_async(&gp_futex, FUTEX_WAKE, 1, |
bc6c15bb MD |
238 | NULL, NULL, 0); |
239 | } | |
240 | } | |
241 | ||
e26fa029 | 242 | static inline int rcu_gp_ongoing(unsigned long *ctr) |
adcfce54 | 243 | { |
27d65bc5 | 244 | unsigned long v; |
adcfce54 | 245 | |
adcfce54 MD |
246 | /* |
247 | * Make sure both tests below are done on the same version of *value | |
248 | * to insure consistency. | |
249 | */ | |
6cf3827c | 250 | v = CMM_LOAD_SHARED(*ctr); |
adcfce54 | 251 | return (v & RCU_GP_CTR_NEST_MASK) && |
02be5561 | 252 | ((v ^ rcu_gp_ctr) & RCU_GP_CTR_PHASE); |
adcfce54 MD |
253 | } |
254 | ||
a5a9f428 PM |
255 | /* |
256 | * Helper for _rcu_read_lock(). The format of rcu_gp_ctr (as well as | |
257 | * the per-thread rcu_reader.ctr) has the upper bits containing a count of | |
258 | * _rcu_read_lock() nesting, and a lower-order bit that contains either zero | |
259 | * or RCU_GP_CTR_PHASE. The smp_mb_slave() ensures that the accesses in | |
260 | * _rcu_read_lock() happen before the subsequent read-side critical section. | |
261 | */ | |
262 | static inline void _rcu_read_lock_update(unsigned long tmp) | |
adcfce54 | 263 | { |
a0b7f7ea | 264 | if (caa_likely(!(tmp & RCU_GP_CTR_NEST_MASK))) { |
bd252a04 | 265 | _CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, _CMM_LOAD_SHARED(rcu_gp_ctr)); |
25cc6d18 | 266 | smp_mb_slave(RCU_MB_GROUP); |
a5a9f428 | 267 | } else |
bd252a04 | 268 | _CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, tmp + RCU_GP_COUNT); |
adcfce54 MD |
269 | } |
270 | ||
a5a9f428 PM |
271 | /* |
272 | * Enter an RCU read-side critical section. | |
273 | * | |
274 | * The first cmm_barrier() call ensures that the compiler does not reorder | |
275 | * the body of _rcu_read_lock() with a mutex. | |
276 | * | |
277 | * This function and its helper are both less than 10 lines long. The | |
278 | * intent is that this function meets the 10-line criterion in LGPL, | |
279 | * allowing this function to be invoked directly from non-LGPL code. | |
280 | */ | |
281 | static inline void _rcu_read_lock(void) | |
adcfce54 | 282 | { |
27d65bc5 | 283 | unsigned long tmp; |
bc6c15bb | 284 | |
a5a9f428 | 285 | cmm_barrier(); |
bd252a04 | 286 | tmp = URCU_TLS(rcu_reader).ctr; |
a5a9f428 PM |
287 | _rcu_read_lock_update(tmp); |
288 | } | |
289 | ||
290 | /* | |
291 | * This is a helper function for _rcu_read_unlock(). | |
292 | * | |
293 | * The first smp_mb_slave() call ensures that the critical section is | |
294 | * seen to precede the store to rcu_reader.ctr. | |
295 | * The second smp_mb_slave() call ensures that we write to rcu_reader.ctr | |
296 | * before reading the update-side futex. | |
297 | */ | |
298 | static inline void _rcu_read_unlock_update_and_wakeup(unsigned long tmp) | |
299 | { | |
a0b7f7ea | 300 | if (caa_likely((tmp & RCU_GP_CTR_NEST_MASK) == RCU_GP_COUNT)) { |
25cc6d18 | 301 | smp_mb_slave(RCU_MB_GROUP); |
bd252a04 | 302 | _CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, URCU_TLS(rcu_reader).ctr - RCU_GP_COUNT); |
25cc6d18 | 303 | smp_mb_slave(RCU_MB_GROUP); |
bc6c15bb | 304 | wake_up_gp(); |
a5a9f428 | 305 | } else |
bd252a04 | 306 | _CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, URCU_TLS(rcu_reader).ctr - RCU_GP_COUNT); |
a5a9f428 PM |
307 | } |
308 | ||
309 | /* | |
310 | * Exit an RCU read-side crtical section. Both this function and its | |
311 | * helper are smaller than 10 lines of code, and are intended to be | |
312 | * usable by non-LGPL code, as called out in LGPL. | |
313 | */ | |
314 | static inline void _rcu_read_unlock(void) | |
315 | { | |
316 | unsigned long tmp; | |
317 | ||
318 | tmp = URCU_TLS(rcu_reader).ctr; | |
319 | _rcu_read_unlock_update_and_wakeup(tmp); | |
5481ddb3 | 320 | cmm_barrier(); /* Ensure the compiler does not reorder us with mutex */ |
adcfce54 MD |
321 | } |
322 | ||
ad918eeb | 323 | #ifdef __cplusplus |
36bc70a8 MD |
324 | } |
325 | #endif | |
326 | ||
adcfce54 | 327 | #endif /* _URCU_STATIC_H */ |