/usr/include/urcu/static/urcu-qsbr.h is in liburcu-dev 0.7.12-0ubuntu2.
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 | #ifndef _URCU_QSBR_STATIC_H
#define _URCU_QSBR_STATIC_H
/*
* urcu-qsbr-static.h
*
* Userspace RCU QSBR header.
*
* TO BE INCLUDED ONLY IN CODE THAT IS TO BE RECOMPILED ON EACH LIBURCU
* RELEASE. 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 <assert.h>
#include <limits.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>
#include <urcu/tls-compat.h>
#ifdef __cplusplus
extern "C" {
#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.
*/
#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)
/* maximum sleep delay, in us */
#define MAX_SLEEP 50
extern unsigned int yield_active;
extern DECLARE_URCU_TLS(unsigned int, rand_yield);
static inline void debug_yield_read(void)
{
if (yield_active & YIELD_READ)
if (rand_r(&URCU_TLS(rand_yield)) & 0x1)
usleep(rand_r(&URCU_TLS(rand_yield)) % MAX_SLEEP);
}
static inline void debug_yield_write(void)
{
if (yield_active & YIELD_WRITE)
if (rand_r(&URCU_TLS(rand_yield)) & 0x1)
usleep(rand_r(&URCU_TLS(rand_yield)) % MAX_SLEEP);
}
static inline void debug_yield_init(void)
{
URCU_TLS(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
#define RCU_GP_ONLINE (1UL << 0)
#define RCU_GP_CTR (1UL << 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;
/* Data used for registry */
struct cds_list_head node __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
int waiting;
pthread_t tid;
};
extern DECLARE_URCU_TLS(struct rcu_reader, 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(_CMM_LOAD_SHARED(URCU_TLS(rcu_reader).waiting))) {
_CMM_STORE_SHARED(URCU_TLS(rcu_reader).waiting, 0);
cmm_smp_mb();
if (uatomic_read(&gp_futex) != -1)
return;
uatomic_set(&gp_futex, 0);
futex_noasync(&gp_futex, FUTEX_WAKE, 1,
NULL, NULL, 0);
}
}
static inline int rcu_gp_ongoing(unsigned long *ctr)
{
unsigned long v;
v = CMM_LOAD_SHARED(*ctr);
return v && (v != rcu_gp_ctr);
}
/*
* Enter an RCU read-side critical section.
*
* This function is less than 10 lines long. The intent is that this
* function meets the 10-line criterion for LGPL, allowing this function
* to be invoked directly from non-LGPL code.
*/
static inline void _rcu_read_lock(void)
{
rcu_assert(URCU_TLS(rcu_reader).ctr);
}
/*
* Exit an RCU read-side critical section.
*
* This function is less than 10 lines long. The intent is that this
* function meets the 10-line criterion for LGPL, allowing this function
* to be invoked directly from non-LGPL code.
*/
static inline void _rcu_read_unlock(void)
{
}
/*
* Inform RCU of a quiescent state.
*
* This function is less than 10 lines long. The intent is that this
* function meets the 10-line criterion for LGPL, allowing this function
* to be invoked directly from non-LGPL code.
*/
static inline void _rcu_quiescent_state(void)
{
cmm_smp_mb();
_CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, _CMM_LOAD_SHARED(rcu_gp_ctr));
cmm_smp_mb(); /* write URCU_TLS(rcu_reader).ctr before read futex */
wake_up_gp();
cmm_smp_mb();
}
/*
* Take a thread offline, prohibiting it from entering further RCU
* read-side critical sections.
*
* This function is less than 10 lines long. The intent is that this
* function meets the 10-line criterion for LGPL, allowing this function
* to be invoked directly from non-LGPL code.
*/
static inline void _rcu_thread_offline(void)
{
cmm_smp_mb();
CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, 0);
cmm_smp_mb(); /* write URCU_TLS(rcu_reader).ctr before read futex */
wake_up_gp();
cmm_barrier(); /* Ensure the compiler does not reorder us with mutex */
}
/*
* Bring a thread online, allowing it to once again enter RCU
* read-side critical sections.
*
* This function is less than 10 lines long. The intent is that this
* function meets the 10-line criterion for LGPL, allowing this function
* to be invoked directly from non-LGPL code.
*/
static inline void _rcu_thread_online(void)
{
cmm_barrier(); /* Ensure the compiler does not reorder us with mutex */
_CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, CMM_LOAD_SHARED(rcu_gp_ctr));
cmm_smp_mb();
}
#ifdef __cplusplus
}
#endif
#endif /* _URCU_QSBR_STATIC_H */
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