/usr/include/urcu/static/urcu.h is in liburcu-dev 0.6.7-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 | #ifndef _URCU_STATIC_H
#define _URCU_STATIC_H
/*
* urcu-static.h
*
* Userspace RCU header.
*
* TO BE INCLUDED ONLY IN LGPL-COMPATIBLE CODE. See urcu.h for linking
* dynamically with the userspace rcu library.
*
* Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
* Copyright (c) 2009 Paul E. McKenney, IBM Corporation.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* IBM's contributions to this file may be relicensed under LGPLv2 or later.
*/
#include <stdlib.h>
#include <pthread.h>
#include <unistd.h>
#include <stdint.h>
#include <urcu/compiler.h>
#include <urcu/arch.h>
#include <urcu/system.h>
#include <urcu/uatomic.h>
#include <urcu/list.h>
#include <urcu/futex.h>
#ifdef __cplusplus
extern "C" {
#endif
/* Default is RCU_MEMBARRIER */
#if !defined(RCU_MEMBARRIER) && !defined(RCU_MB) && !defined(RCU_SIGNAL)
#define RCU_MEMBARRIER
#endif
/*
* RCU_MEMBARRIER is only possibly available on Linux. Fallback to RCU_MB
* otherwise.
*/
#if !defined(__linux__) && defined(RCU_MEMBARRIER)
#undef RCU_MEMBARRIER
#define RCU_MB
#endif
#ifdef RCU_MEMBARRIER
#include <syscall.h>
/* If the headers do not support SYS_membarrier, statically use RCU_MB */
#ifdef SYS_membarrier
# define MEMBARRIER_EXPEDITED (1 << 0)
# define MEMBARRIER_DELAYED (1 << 1)
# define MEMBARRIER_QUERY (1 << 16)
# define membarrier(...) syscall(SYS_membarrier, __VA_ARGS__)
#else
# undef RCU_MEMBARRIER
# define RCU_MB
#endif
#endif
/*
* This code section can only be included in LGPL 2.1 compatible source code.
* See below for the function call wrappers which can be used in code meant to
* be only linked with the Userspace RCU library. This comes with a small
* performance degradation on the read-side due to the added function calls.
* This is required to permit relinking with newer versions of the library.
*/
/*
* The signal number used by the RCU library can be overridden with
* -DSIGRCU= when compiling the library.
* Provide backward compatibility for liburcu 0.3.x SIGURCU.
*/
#ifdef SIGURCU
#define SIGRCU SIGURCU
#endif
#ifndef SIGRCU
#define SIGRCU SIGUSR1
#endif
#ifdef DEBUG_RCU
#define rcu_assert(args...) assert(args)
#else
#define rcu_assert(args...)
#endif
#ifdef DEBUG_YIELD
#include <sched.h>
#include <time.h>
#include <pthread.h>
#include <unistd.h>
#define YIELD_READ (1 << 0)
#define YIELD_WRITE (1 << 1)
/*
* Updates with RCU_SIGNAL are much slower. Account this in the delay.
*/
#ifdef RCU_SIGNAL
/* maximum sleep delay, in us */
#define MAX_SLEEP 30000
#else
#define MAX_SLEEP 50
#endif
extern unsigned int yield_active;
extern unsigned int __thread rand_yield;
static inline void debug_yield_read(void)
{
if (yield_active & YIELD_READ)
if (rand_r(&rand_yield) & 0x1)
usleep(rand_r(&rand_yield) % MAX_SLEEP);
}
static inline void debug_yield_write(void)
{
if (yield_active & YIELD_WRITE)
if (rand_r(&rand_yield) & 0x1)
usleep(rand_r(&rand_yield) % MAX_SLEEP);
}
static inline void debug_yield_init(void)
{
rand_yield = time(NULL) ^ (unsigned long) pthread_self();
}
#else
static inline void debug_yield_read(void)
{
}
static inline void debug_yield_write(void)
{
}
static inline void debug_yield_init(void)
{
}
#endif
/*
* RCU memory barrier broadcast group. Currently, only broadcast to all process
* threads is supported (group 0).
*
* Slave barriers are only guaranteed to be ordered wrt master barriers.
*
* The pair ordering is detailed as (O: ordered, X: not ordered) :
* slave master
* slave X O
* master O O
*/
#define MB_GROUP_ALL 0
#define RCU_MB_GROUP MB_GROUP_ALL
#ifdef RCU_MEMBARRIER
extern int has_sys_membarrier;
static inline void smp_mb_slave(int group)
{
if (caa_likely(has_sys_membarrier))
cmm_barrier();
else
cmm_smp_mb();
}
#endif
#ifdef RCU_MB
static inline void smp_mb_slave(int group)
{
cmm_smp_mb();
}
#endif
#ifdef RCU_SIGNAL
static inline void smp_mb_slave(int group)
{
cmm_barrier();
}
#endif
/*
* The trick here is that RCU_GP_CTR_PHASE must be a multiple of 8 so we can use
* a full 8-bits, 16-bits or 32-bits bitmask for the lower order bits.
*/
#define RCU_GP_COUNT (1UL << 0)
/* Use the amount of bits equal to half of the architecture long size */
#define RCU_GP_CTR_PHASE (1UL << (sizeof(unsigned long) << 2))
#define RCU_GP_CTR_NEST_MASK (RCU_GP_CTR_PHASE - 1)
/*
* Global quiescent period counter with low-order bits unused.
* Using a int rather than a char to eliminate false register dependencies
* causing stalls on some architectures.
*/
extern unsigned long rcu_gp_ctr;
struct rcu_reader {
/* Data used by both reader and synchronize_rcu() */
unsigned long ctr;
char need_mb;
/* Data used for registry */
struct cds_list_head node __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
pthread_t tid;
};
extern struct rcu_reader __thread rcu_reader;
extern int32_t gp_futex;
/*
* Wake-up waiting synchronize_rcu(). Called from many concurrent threads.
*/
static inline void wake_up_gp(void)
{
if (caa_unlikely(uatomic_read(&gp_futex) == -1)) {
uatomic_set(&gp_futex, 0);
futex_async(&gp_futex, FUTEX_WAKE, 1,
NULL, NULL, 0);
}
}
static inline int rcu_gp_ongoing(unsigned long *ctr)
{
unsigned long v;
/*
* Make sure both tests below are done on the same version of *value
* to insure consistency.
*/
v = CMM_LOAD_SHARED(*ctr);
return (v & RCU_GP_CTR_NEST_MASK) &&
((v ^ rcu_gp_ctr) & RCU_GP_CTR_PHASE);
}
static inline void _rcu_read_lock(void)
{
unsigned long tmp;
cmm_barrier(); /* Ensure the compiler does not reorder us with mutex */
tmp = rcu_reader.ctr;
/*
* rcu_gp_ctr is
* RCU_GP_COUNT | (~RCU_GP_CTR_PHASE or RCU_GP_CTR_PHASE)
*/
if (caa_likely(!(tmp & RCU_GP_CTR_NEST_MASK))) {
_CMM_STORE_SHARED(rcu_reader.ctr, _CMM_LOAD_SHARED(rcu_gp_ctr));
/*
* Set active readers count for outermost nesting level before
* accessing the pointer. See smp_mb_master().
*/
smp_mb_slave(RCU_MB_GROUP);
} else {
_CMM_STORE_SHARED(rcu_reader.ctr, tmp + RCU_GP_COUNT);
}
}
static inline void _rcu_read_unlock(void)
{
unsigned long tmp;
tmp = rcu_reader.ctr;
/*
* Finish using rcu before decrementing the pointer.
* See smp_mb_master().
*/
if (caa_likely((tmp & RCU_GP_CTR_NEST_MASK) == RCU_GP_COUNT)) {
smp_mb_slave(RCU_MB_GROUP);
_CMM_STORE_SHARED(rcu_reader.ctr, rcu_reader.ctr - RCU_GP_COUNT);
/* write rcu_reader.ctr before read futex */
smp_mb_slave(RCU_MB_GROUP);
wake_up_gp();
} else {
_CMM_STORE_SHARED(rcu_reader.ctr, rcu_reader.ctr - RCU_GP_COUNT);
}
cmm_barrier(); /* Ensure the compiler does not reorder us with mutex */
}
#ifdef __cplusplus
}
#endif
#endif /* _URCU_STATIC_H */
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