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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 | ||
de07ab96 MD |
63 | /* |
64 | * The ABI of sys_membarrier changed after its original implementation. | |
65 | * Disable it for now. Use RCU_MB flavor instead. | |
66 | */ | |
fdf01eed | 67 | #ifdef RCU_MEMBARRIER |
de07ab96 MD |
68 | #undef RCU_MEMBARRIER |
69 | #define RCU_MB | |
fdf01eed MD |
70 | #endif |
71 | ||
adcfce54 MD |
72 | /* |
73 | * This code section can only be included in LGPL 2.1 compatible source code. | |
74 | * See below for the function call wrappers which can be used in code meant to | |
75 | * be only linked with the Userspace RCU library. This comes with a small | |
76 | * performance degradation on the read-side due to the added function calls. | |
77 | * This is required to permit relinking with newer versions of the library. | |
78 | */ | |
79 | ||
80 | /* | |
81 | * The signal number used by the RCU library can be overridden with | |
02be5561 | 82 | * -DSIGRCU= when compiling the library. |
ddf7eefb | 83 | * Provide backward compatibility for liburcu 0.3.x SIGURCU. |
adcfce54 | 84 | */ |
ddf7eefb MD |
85 | #ifdef SIGURCU |
86 | #define SIGRCU SIGURCU | |
87 | #endif | |
88 | ||
02be5561 MD |
89 | #ifndef SIGRCU |
90 | #define SIGRCU SIGUSR1 | |
adcfce54 MD |
91 | #endif |
92 | ||
7ac06cef MD |
93 | #ifdef DEBUG_RCU |
94 | #define rcu_assert(args...) assert(args) | |
95 | #else | |
96 | #define rcu_assert(args...) | |
97 | #endif | |
98 | ||
adcfce54 MD |
99 | #ifdef DEBUG_YIELD |
100 | #include <sched.h> | |
101 | #include <time.h> | |
102 | #include <pthread.h> | |
103 | #include <unistd.h> | |
104 | ||
105 | #define YIELD_READ (1 << 0) | |
106 | #define YIELD_WRITE (1 << 1) | |
107 | ||
b4ce1526 | 108 | /* |
fdf01eed | 109 | * Updates with RCU_SIGNAL are much slower. Account this in the delay. |
b4ce1526 | 110 | */ |
fdf01eed | 111 | #ifdef RCU_SIGNAL |
adcfce54 | 112 | /* maximum sleep delay, in us */ |
adcfce54 | 113 | #define MAX_SLEEP 30000 |
fdf01eed MD |
114 | #else |
115 | #define MAX_SLEEP 50 | |
adcfce54 MD |
116 | #endif |
117 | ||
118 | extern unsigned int yield_active; | |
bd252a04 | 119 | extern DECLARE_URCU_TLS(unsigned int, rand_yield); |
adcfce54 MD |
120 | |
121 | static inline void debug_yield_read(void) | |
122 | { | |
123 | if (yield_active & YIELD_READ) | |
bd252a04 MD |
124 | if (rand_r(&URCU_TLS(rand_yield)) & 0x1) |
125 | usleep(rand_r(&URCU_TLS(rand_yield)) % MAX_SLEEP); | |
adcfce54 MD |
126 | } |
127 | ||
128 | static inline void debug_yield_write(void) | |
129 | { | |
130 | if (yield_active & YIELD_WRITE) | |
bd252a04 MD |
131 | if (rand_r(&URCU_TLS(rand_yield)) & 0x1) |
132 | usleep(rand_r(&URCU_TLS(rand_yield)) % MAX_SLEEP); | |
adcfce54 MD |
133 | } |
134 | ||
135 | static inline void debug_yield_init(void) | |
136 | { | |
bd252a04 | 137 | URCU_TLS(rand_yield) = time(NULL) ^ (unsigned long) pthread_self(); |
adcfce54 MD |
138 | } |
139 | #else | |
140 | static inline void debug_yield_read(void) | |
141 | { | |
142 | } | |
143 | ||
144 | static inline void debug_yield_write(void) | |
145 | { | |
146 | } | |
147 | ||
148 | static inline void debug_yield_init(void) | |
149 | { | |
150 | ||
151 | } | |
152 | #endif | |
153 | ||
25cc6d18 MD |
154 | /* |
155 | * RCU memory barrier broadcast group. Currently, only broadcast to all process | |
156 | * threads is supported (group 0). | |
157 | * | |
158 | * Slave barriers are only guaranteed to be ordered wrt master barriers. | |
159 | * | |
160 | * The pair ordering is detailed as (O: ordered, X: not ordered) : | |
161 | * slave master | |
162 | * slave X O | |
163 | * master O O | |
164 | */ | |
165 | ||
166 | #define MB_GROUP_ALL 0 | |
167 | #define RCU_MB_GROUP MB_GROUP_ALL | |
168 | ||
fdf01eed MD |
169 | #ifdef RCU_MEMBARRIER |
170 | extern int has_sys_membarrier; | |
171 | ||
25cc6d18 | 172 | static inline void smp_mb_slave(int group) |
fdf01eed | 173 | { |
a0b7f7ea | 174 | if (caa_likely(has_sys_membarrier)) |
5481ddb3 | 175 | cmm_barrier(); |
fdf01eed | 176 | else |
5481ddb3 | 177 | cmm_smp_mb(); |
fdf01eed MD |
178 | } |
179 | #endif | |
180 | ||
02be5561 | 181 | #ifdef RCU_MB |
25cc6d18 | 182 | static inline void smp_mb_slave(int group) |
adcfce54 | 183 | { |
5481ddb3 | 184 | cmm_smp_mb(); |
adcfce54 | 185 | } |
fdf01eed MD |
186 | #endif |
187 | ||
188 | #ifdef RCU_SIGNAL | |
25cc6d18 | 189 | static inline void smp_mb_slave(int group) |
adcfce54 | 190 | { |
5481ddb3 | 191 | cmm_barrier(); |
adcfce54 MD |
192 | } |
193 | #endif | |
194 | ||
195 | /* | |
02be5561 MD |
196 | * The trick here is that RCU_GP_CTR_PHASE must be a multiple of 8 so we can use |
197 | * a full 8-bits, 16-bits or 32-bits bitmask for the lower order bits. | |
adcfce54 MD |
198 | */ |
199 | #define RCU_GP_COUNT (1UL << 0) | |
200 | /* Use the amount of bits equal to half of the architecture long size */ | |
27d65bc5 | 201 | #define RCU_GP_CTR_PHASE (1UL << (sizeof(unsigned long) << 2)) |
02be5561 | 202 | #define RCU_GP_CTR_NEST_MASK (RCU_GP_CTR_PHASE - 1) |
adcfce54 MD |
203 | |
204 | /* | |
205 | * Global quiescent period counter with low-order bits unused. | |
206 | * Using a int rather than a char to eliminate false register dependencies | |
207 | * causing stalls on some architectures. | |
208 | */ | |
27d65bc5 | 209 | extern unsigned long rcu_gp_ctr; |
adcfce54 | 210 | |
02be5561 | 211 | struct rcu_reader { |
bd1a5e15 | 212 | /* Data used by both reader and synchronize_rcu() */ |
27d65bc5 | 213 | unsigned long ctr; |
e3b0cef0 | 214 | char need_mb; |
bd1a5e15 | 215 | /* Data used for registry */ |
16aa9ee8 | 216 | struct cds_list_head node __attribute__((aligned(CAA_CACHE_LINE_SIZE))); |
bd1a5e15 | 217 | pthread_t tid; |
e3b0cef0 MD |
218 | }; |
219 | ||
bd252a04 | 220 | extern DECLARE_URCU_TLS(struct rcu_reader, rcu_reader); |
adcfce54 | 221 | |
6d841bc2 | 222 | extern int32_t gp_futex; |
bc6c15bb MD |
223 | |
224 | /* | |
225 | * Wake-up waiting synchronize_rcu(). Called from many concurrent threads. | |
226 | */ | |
227 | static inline void wake_up_gp(void) | |
228 | { | |
a0b7f7ea | 229 | if (caa_unlikely(uatomic_read(&gp_futex) == -1)) { |
ec4e58a3 | 230 | uatomic_set(&gp_futex, 0); |
11eb040f MD |
231 | /* |
232 | * Ignoring return value until we can make this function | |
233 | * return something (because urcu_die() is not publicly | |
234 | * exposed). | |
235 | */ | |
236 | (void) futex_async(&gp_futex, FUTEX_WAKE, 1, | |
237 | NULL, NULL, 0); | |
bc6c15bb MD |
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 | ||
a5a9f428 PM |
254 | /* |
255 | * Helper for _rcu_read_lock(). The format of rcu_gp_ctr (as well as | |
256 | * the per-thread rcu_reader.ctr) has the upper bits containing a count of | |
257 | * _rcu_read_lock() nesting, and a lower-order bit that contains either zero | |
258 | * or RCU_GP_CTR_PHASE. The smp_mb_slave() ensures that the accesses in | |
259 | * _rcu_read_lock() happen before the subsequent read-side critical section. | |
260 | */ | |
261 | static inline void _rcu_read_lock_update(unsigned long tmp) | |
adcfce54 | 262 | { |
a0b7f7ea | 263 | if (caa_likely(!(tmp & RCU_GP_CTR_NEST_MASK))) { |
bd252a04 | 264 | _CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, _CMM_LOAD_SHARED(rcu_gp_ctr)); |
25cc6d18 | 265 | smp_mb_slave(RCU_MB_GROUP); |
a5a9f428 | 266 | } else |
bd252a04 | 267 | _CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, tmp + RCU_GP_COUNT); |
adcfce54 MD |
268 | } |
269 | ||
a5a9f428 PM |
270 | /* |
271 | * Enter an RCU read-side critical section. | |
272 | * | |
273 | * The first cmm_barrier() call ensures that the compiler does not reorder | |
274 | * the body of _rcu_read_lock() with a mutex. | |
275 | * | |
276 | * This function and its helper are both less than 10 lines long. The | |
277 | * intent is that this function meets the 10-line criterion in LGPL, | |
278 | * allowing this function to be invoked directly from non-LGPL code. | |
279 | */ | |
280 | static inline void _rcu_read_lock(void) | |
adcfce54 | 281 | { |
27d65bc5 | 282 | unsigned long tmp; |
bc6c15bb | 283 | |
a5a9f428 | 284 | cmm_barrier(); |
bd252a04 | 285 | tmp = URCU_TLS(rcu_reader).ctr; |
a5a9f428 PM |
286 | _rcu_read_lock_update(tmp); |
287 | } | |
288 | ||
289 | /* | |
290 | * This is a helper function for _rcu_read_unlock(). | |
291 | * | |
292 | * The first smp_mb_slave() call ensures that the critical section is | |
293 | * seen to precede the store to rcu_reader.ctr. | |
294 | * The second smp_mb_slave() call ensures that we write to rcu_reader.ctr | |
295 | * before reading the update-side futex. | |
296 | */ | |
297 | static inline void _rcu_read_unlock_update_and_wakeup(unsigned long tmp) | |
298 | { | |
a0b7f7ea | 299 | if (caa_likely((tmp & RCU_GP_CTR_NEST_MASK) == RCU_GP_COUNT)) { |
25cc6d18 | 300 | smp_mb_slave(RCU_MB_GROUP); |
bd252a04 | 301 | _CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, URCU_TLS(rcu_reader).ctr - RCU_GP_COUNT); |
25cc6d18 | 302 | smp_mb_slave(RCU_MB_GROUP); |
bc6c15bb | 303 | wake_up_gp(); |
a5a9f428 | 304 | } else |
bd252a04 | 305 | _CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, URCU_TLS(rcu_reader).ctr - RCU_GP_COUNT); |
a5a9f428 PM |
306 | } |
307 | ||
308 | /* | |
309 | * Exit an RCU read-side crtical section. Both this function and its | |
310 | * helper are smaller than 10 lines of code, and are intended to be | |
311 | * usable by non-LGPL code, as called out in LGPL. | |
312 | */ | |
313 | static inline void _rcu_read_unlock(void) | |
314 | { | |
315 | unsigned long tmp; | |
316 | ||
317 | tmp = URCU_TLS(rcu_reader).ctr; | |
318 | _rcu_read_unlock_update_and_wakeup(tmp); | |
5481ddb3 | 319 | cmm_barrier(); /* Ensure the compiler does not reorder us with mutex */ |
adcfce54 MD |
320 | } |
321 | ||
ad918eeb | 322 | #ifdef __cplusplus |
36bc70a8 MD |
323 | } |
324 | #endif | |
325 | ||
adcfce54 | 326 | #endif /* _URCU_STATIC_H */ |