/usr/include/urcu/static/urcu-bp.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 | #ifndef _URCU_BP_STATIC_H
#define _URCU_BP_STATIC_H
/*
* urcu-bp-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 <urcu/compiler.h>
#include <urcu/arch.h>
#include <urcu/system.h>
#include <urcu/uatomic.h>
#include <urcu/list.h>
/*
* 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 __cplusplus
extern "C" {
#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 without RCU_MB are much slower. Account this in
* the delay.
*/
/* maximum sleep delay, in us */
#define MAX_SLEEP 50
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) ^ 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
/*
* 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(long) << 2))
#define RCU_GP_CTR_NEST_MASK (RCU_GP_CTR_PHASE - 1)
/*
* Used internally by _rcu_read_lock.
*/
extern void rcu_bp_register(void);
/*
* 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 long rcu_gp_ctr;
struct rcu_reader {
/* Data used by both reader and synchronize_rcu() */
long ctr;
/* Data used for registry */
struct cds_list_head node __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
pthread_t tid;
int alloc; /* registry entry allocated */
};
/*
* Bulletproof version keeps a pointer to a registry not part of the TLS.
* Adds a pointer dereference on the read-side, but won't require to unregister
* the reader thread.
*/
extern struct rcu_reader __thread *rcu_reader;
static inline int rcu_old_gp_ongoing(long *value)
{
long v;
if (value == NULL)
return 0;
/*
* Make sure both tests below are done on the same version of *value
* to insure consistency.
*/
v = CMM_LOAD_SHARED(*value);
return (v & RCU_GP_CTR_NEST_MASK) &&
((v ^ rcu_gp_ctr) & RCU_GP_CTR_PHASE);
}
static inline void _rcu_read_lock(void)
{
long tmp;
/* Check if registered */
if (caa_unlikely(!rcu_reader))
rcu_bp_register();
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.
*/
cmm_smp_mb();
} else {
_CMM_STORE_SHARED(rcu_reader->ctr, tmp + RCU_GP_COUNT);
}
}
static inline void _rcu_read_unlock(void)
{
/*
* Finish using rcu before decrementing the pointer.
*/
cmm_smp_mb();
_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_BP_STATIC_H */
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