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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 | |
d8d9a340 | 37 | #include <urcu/config.h> |
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> |
bd252a04 | 44 | #include <urcu/tls-compat.h> |
a77f7d82 | 45 | #include <urcu/debug.h> |
22e3a77f | 46 | #include <urcu/static/urcu-signal.h> |
bc6c15bb | 47 | |
36bc70a8 MD |
48 | #ifdef __cplusplus |
49 | extern "C" { | |
67ecffc0 | 50 | #endif |
36bc70a8 | 51 | |
65f1e634 | 52 | /* Default is RCU_MEMBARRIER */ |
fdf01eed | 53 | #if !defined(RCU_MEMBARRIER) && !defined(RCU_MB) && !defined(RCU_SIGNAL) |
65f1e634 MD |
54 | #define RCU_MEMBARRIER |
55 | #endif | |
56 | ||
adcfce54 MD |
57 | /* |
58 | * This code section can only be included in LGPL 2.1 compatible source code. | |
59 | * See below for the function call wrappers which can be used in code meant to | |
60 | * be only linked with the Userspace RCU library. This comes with a small | |
61 | * performance degradation on the read-side due to the added function calls. | |
62 | * This is required to permit relinking with newer versions of the library. | |
63 | */ | |
64 | ||
fd189fa5 MD |
65 | enum rcu_state { |
66 | RCU_READER_ACTIVE_CURRENT, | |
67 | RCU_READER_ACTIVE_OLD, | |
68 | RCU_READER_INACTIVE, | |
69 | }; | |
70 | ||
25cc6d18 | 71 | /* |
25cc6d18 MD |
72 | * Slave barriers are only guaranteed to be ordered wrt master barriers. |
73 | * | |
74 | * The pair ordering is detailed as (O: ordered, X: not ordered) : | |
75 | * slave master | |
76 | * slave X O | |
77 | * master O O | |
78 | */ | |
79 | ||
fdf01eed | 80 | #ifdef RCU_MEMBARRIER |
d8d9a340 MD |
81 | #ifdef CONFIG_RCU_FORCE_SYS_MEMBARRIER |
82 | #define rcu_has_sys_membarrier_memb 1 | |
83 | #else | |
84 | extern int rcu_has_sys_membarrier_memb; | |
85 | #endif | |
fdf01eed | 86 | |
a4922ed9 | 87 | static inline void smp_mb_slave(void) |
fdf01eed | 88 | { |
d8d9a340 | 89 | if (caa_likely(rcu_has_sys_membarrier_memb)) |
5481ddb3 | 90 | cmm_barrier(); |
fdf01eed | 91 | else |
5481ddb3 | 92 | cmm_smp_mb(); |
fdf01eed MD |
93 | } |
94 | #endif | |
95 | ||
02be5561 | 96 | #ifdef RCU_MB |
a4922ed9 | 97 | static inline void smp_mb_slave(void) |
adcfce54 | 98 | { |
5481ddb3 | 99 | cmm_smp_mb(); |
adcfce54 | 100 | } |
fdf01eed MD |
101 | #endif |
102 | ||
103 | #ifdef RCU_SIGNAL | |
a4922ed9 | 104 | static inline void smp_mb_slave(void) |
adcfce54 | 105 | { |
5481ddb3 | 106 | cmm_barrier(); |
adcfce54 MD |
107 | } |
108 | #endif | |
109 | ||
110 | /* | |
02be5561 MD |
111 | * The trick here is that RCU_GP_CTR_PHASE must be a multiple of 8 so we can use |
112 | * a full 8-bits, 16-bits or 32-bits bitmask for the lower order bits. | |
adcfce54 MD |
113 | */ |
114 | #define RCU_GP_COUNT (1UL << 0) | |
115 | /* Use the amount of bits equal to half of the architecture long size */ | |
27d65bc5 | 116 | #define RCU_GP_CTR_PHASE (1UL << (sizeof(unsigned long) << 2)) |
02be5561 | 117 | #define RCU_GP_CTR_NEST_MASK (RCU_GP_CTR_PHASE - 1) |
adcfce54 | 118 | |
4de0cd31 | 119 | struct rcu_gp { |
ed1b099e LJ |
120 | /* |
121 | * Global grace period counter. | |
122 | * Contains the current RCU_GP_CTR_PHASE. | |
123 | * Also has a RCU_GP_COUNT of 1, to accelerate the reader fast path. | |
124 | * Written to only by writer with mutex taken. | |
125 | * Read by both writer and readers. | |
126 | */ | |
127 | unsigned long ctr; | |
128 | ||
129 | int32_t futex; | |
130 | } __attribute__((aligned(CAA_CACHE_LINE_SIZE))); | |
131 | ||
4de0cd31 | 132 | extern struct rcu_gp rcu_gp; |
adcfce54 | 133 | |
02be5561 | 134 | struct rcu_reader { |
bd1a5e15 | 135 | /* Data used by both reader and synchronize_rcu() */ |
27d65bc5 | 136 | unsigned long ctr; |
e3b0cef0 | 137 | char need_mb; |
bd1a5e15 | 138 | /* Data used for registry */ |
16aa9ee8 | 139 | struct cds_list_head node __attribute__((aligned(CAA_CACHE_LINE_SIZE))); |
bd1a5e15 | 140 | pthread_t tid; |
a77f7d82 MD |
141 | /* Reader registered flag, for internal checks. */ |
142 | unsigned int registered:1; | |
e3b0cef0 MD |
143 | }; |
144 | ||
bd252a04 | 145 | extern DECLARE_URCU_TLS(struct rcu_reader, rcu_reader); |
adcfce54 | 146 | |
bc6c15bb MD |
147 | /* |
148 | * Wake-up waiting synchronize_rcu(). Called from many concurrent threads. | |
149 | */ | |
150 | static inline void wake_up_gp(void) | |
151 | { | |
ed1b099e LJ |
152 | if (caa_unlikely(uatomic_read(&rcu_gp.futex) == -1)) { |
153 | uatomic_set(&rcu_gp.futex, 0); | |
b0a841b4 MD |
154 | /* |
155 | * Ignoring return value until we can make this function | |
156 | * return something (because urcu_die() is not publicly | |
157 | * exposed). | |
158 | */ | |
159 | (void) futex_async(&rcu_gp.futex, FUTEX_WAKE, 1, | |
160 | NULL, NULL, 0); | |
bc6c15bb MD |
161 | } |
162 | } | |
163 | ||
fd189fa5 | 164 | static inline enum rcu_state rcu_reader_state(unsigned long *ctr) |
adcfce54 | 165 | { |
27d65bc5 | 166 | unsigned long v; |
adcfce54 | 167 | |
adcfce54 MD |
168 | /* |
169 | * Make sure both tests below are done on the same version of *value | |
170 | * to insure consistency. | |
171 | */ | |
6cf3827c | 172 | v = CMM_LOAD_SHARED(*ctr); |
fd189fa5 MD |
173 | if (!(v & RCU_GP_CTR_NEST_MASK)) |
174 | return RCU_READER_INACTIVE; | |
ed1b099e | 175 | if (!((v ^ rcu_gp.ctr) & RCU_GP_CTR_PHASE)) |
fd189fa5 MD |
176 | return RCU_READER_ACTIVE_CURRENT; |
177 | return RCU_READER_ACTIVE_OLD; | |
adcfce54 MD |
178 | } |
179 | ||
a5a9f428 | 180 | /* |
ed1b099e | 181 | * Helper for _rcu_read_lock(). The format of rcu_gp.ctr (as well as |
a5a9f428 PM |
182 | * the per-thread rcu_reader.ctr) has the upper bits containing a count of |
183 | * _rcu_read_lock() nesting, and a lower-order bit that contains either zero | |
184 | * or RCU_GP_CTR_PHASE. The smp_mb_slave() ensures that the accesses in | |
185 | * _rcu_read_lock() happen before the subsequent read-side critical section. | |
186 | */ | |
187 | static inline void _rcu_read_lock_update(unsigned long tmp) | |
adcfce54 | 188 | { |
a0b7f7ea | 189 | if (caa_likely(!(tmp & RCU_GP_CTR_NEST_MASK))) { |
ed1b099e | 190 | _CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, _CMM_LOAD_SHARED(rcu_gp.ctr)); |
a4922ed9 | 191 | smp_mb_slave(); |
a5a9f428 | 192 | } else |
bd252a04 | 193 | _CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, tmp + RCU_GP_COUNT); |
adcfce54 MD |
194 | } |
195 | ||
a5a9f428 PM |
196 | /* |
197 | * Enter an RCU read-side critical section. | |
198 | * | |
199 | * The first cmm_barrier() call ensures that the compiler does not reorder | |
200 | * the body of _rcu_read_lock() with a mutex. | |
201 | * | |
202 | * This function and its helper are both less than 10 lines long. The | |
203 | * intent is that this function meets the 10-line criterion in LGPL, | |
204 | * allowing this function to be invoked directly from non-LGPL code. | |
205 | */ | |
206 | static inline void _rcu_read_lock(void) | |
adcfce54 | 207 | { |
27d65bc5 | 208 | unsigned long tmp; |
bc6c15bb | 209 | |
a77f7d82 | 210 | urcu_assert(URCU_TLS(rcu_reader).registered); |
a5a9f428 | 211 | cmm_barrier(); |
bd252a04 | 212 | tmp = URCU_TLS(rcu_reader).ctr; |
6ef5ddc9 | 213 | urcu_assert((tmp & RCU_GP_CTR_NEST_MASK) != RCU_GP_CTR_NEST_MASK); |
a5a9f428 PM |
214 | _rcu_read_lock_update(tmp); |
215 | } | |
216 | ||
217 | /* | |
218 | * This is a helper function for _rcu_read_unlock(). | |
219 | * | |
220 | * The first smp_mb_slave() call ensures that the critical section is | |
221 | * seen to precede the store to rcu_reader.ctr. | |
222 | * The second smp_mb_slave() call ensures that we write to rcu_reader.ctr | |
223 | * before reading the update-side futex. | |
224 | */ | |
225 | static inline void _rcu_read_unlock_update_and_wakeup(unsigned long tmp) | |
226 | { | |
a0b7f7ea | 227 | if (caa_likely((tmp & RCU_GP_CTR_NEST_MASK) == RCU_GP_COUNT)) { |
a4922ed9 | 228 | smp_mb_slave(); |
343c8b13 | 229 | _CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, tmp - RCU_GP_COUNT); |
a4922ed9 | 230 | smp_mb_slave(); |
bc6c15bb | 231 | wake_up_gp(); |
a5a9f428 | 232 | } else |
343c8b13 | 233 | _CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, tmp - RCU_GP_COUNT); |
a5a9f428 PM |
234 | } |
235 | ||
236 | /* | |
237 | * Exit an RCU read-side crtical section. Both this function and its | |
238 | * helper are smaller than 10 lines of code, and are intended to be | |
239 | * usable by non-LGPL code, as called out in LGPL. | |
240 | */ | |
241 | static inline void _rcu_read_unlock(void) | |
242 | { | |
243 | unsigned long tmp; | |
244 | ||
a77f7d82 | 245 | urcu_assert(URCU_TLS(rcu_reader).registered); |
a5a9f428 | 246 | tmp = URCU_TLS(rcu_reader).ctr; |
343c8b13 | 247 | urcu_assert(tmp & RCU_GP_CTR_NEST_MASK); |
a5a9f428 | 248 | _rcu_read_unlock_update_and_wakeup(tmp); |
5481ddb3 | 249 | cmm_barrier(); /* Ensure the compiler does not reorder us with mutex */ |
adcfce54 MD |
250 | } |
251 | ||
882f3357 MD |
252 | /* |
253 | * Returns whether within a RCU read-side critical section. | |
254 | * | |
255 | * This function is less than 10 lines long. The intent is that this | |
256 | * function meets the 10-line criterion for LGPL, allowing this function | |
257 | * to be invoked directly from non-LGPL code. | |
258 | */ | |
259 | static inline int _rcu_read_ongoing(void) | |
260 | { | |
261 | return URCU_TLS(rcu_reader).ctr & RCU_GP_CTR_NEST_MASK; | |
262 | } | |
263 | ||
ad918eeb | 264 | #ifdef __cplusplus |
36bc70a8 MD |
265 | } |
266 | #endif | |
267 | ||
adcfce54 | 268 | #endif /* _URCU_STATIC_H */ |