/usr/include/asterisk/spinlock.h is in asterisk-dev 1:13.1.0~dfsg-1.1ubuntu4.
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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 | /*
* Asterisk -- An open source telephony toolkit.
*
* Copyright (C) 2014, Fairview 5 Engineering, LLC
*
* George Joseph <george.joseph@fairview5.com>
*
* See http://www.asterisk.org for more information about
* the Asterisk project. Please do not directly contact
* any of the maintainers of this project for assistance;
* the project provides a web site, mailing lists and IRC
* channels for your use.
*
* This program is free software, distributed under the terms of
* the GNU General Public License Version 2. See the LICENSE file
* at the top of the source tree.
*/
/*! \file
* \brief Spin Locks.
*
* In some atomic operation circumstances the __atomic calls are not quite
* flexible enough but a full fledged mutex or rwlock is too expensive.
*
* Spin locks should be used only for protecting short blocks of critical
* code such as simple compares and assignments. Operations that may block,
* hold a lock, or cause the thread to give up it's timeslice should NEVER
* be attempted in a spin lock.
*
* Because spinlocks must be as lightweight as possible, there are no
* recursion or deadlock checks.
*
*/
#ifndef _ASTERISK_SPINLOCK_H
#define _ASTERISK_SPINLOCK_H
#include <pthread.h>
#include "asterisk/compiler.h"
/*!
* \brief Spinlock Implementation Types
*
* Not all implementations will be available on all platforms.
*
*/
enum ast_spinlock_type {
AST_SPINLOCK_TYPE_GCC_ATOMICS,
AST_SPINLOCK_TYPE_GAS_X86,
AST_SPINLOCK_TYPE_GAS_ARM,
AST_SPINLOCK_TYPE_GAS_SPARC,
AST_SPINLOCK_TYPE_OSX_ATOMICS,
AST_SPINLOCK_TYPE_PTHREAD_SPINLOCK,
AST_SPINLOCK_TYPE_PTHREAD_MUTEX,
};
/*!
* \brief Implementation using GCC Atomics
*
* Specifically, __sync_lock_test_and_set is used to atomically
* set/unset the lock variable.
*
* Most recent gcc implementations support this method and it's performance
* is equal to or better than the assembly implementations hence it is the
* most preferred implementation on all platforms.
*
*/
#ifdef HAVE_GCC_ATOMICS
#define AST_SPINLOCK_TYPE AST_SPINLOCK_TYPE_GCC_ATOMICS
#define AST_SPINLOCK_TYPE_LABEL "gcc_atomics"
typedef volatile unsigned int ast_spinlock_t;
static force_inline int ast_spinlock_init(ast_spinlock_t *lock)
{
*lock = 0;
return 0;
}
static force_inline int ast_spinlock_lock(ast_spinlock_t *lock)
{
while (__sync_lock_test_and_set(lock, 1)) {
while(*lock) {
}
}
return 0;
}
static force_inline int ast_spinlock_trylock(ast_spinlock_t *lock)
{
return __sync_lock_test_and_set(lock, 1);
}
static force_inline int ast_spinlock_unlock(ast_spinlock_t *lock)
{
__sync_lock_release(lock);
return 0;
}
static force_inline int ast_spinlock_destroy(ast_spinlock_t *lock)
{
return 0;
}
#endif
/*!
* \brief Implementation using x86 Assembly
*
* For x86 implementations that don't support gcc atomics,
* this is the next best method.
*
*/
#if (defined(__x86_64__) || defined(__i386__)) && !defined(AST_SPINLOCK_TYPE)
#define AST_SPINLOCK_TYPE AST_SPINLOCK_TYPE_GAS_X86
#define AST_SPINLOCK_TYPE_LABEL "gas_x86"
typedef volatile unsigned int ast_spinlock_t;
static force_inline int ast_spinlock_init(ast_spinlock_t *lock)
{
*lock = 0;
return 0;
}
static force_inline int x86chgl(ast_spinlock_t *p, unsigned int v)
{
__asm __volatile (
" xchg %0, %1 ;"
: "+r" (v), "=m" (*p)
: "m" (*p)
);
return (v);
}
static force_inline int ast_spinlock_lock(ast_spinlock_t *lock)
{
while (x86chgl(lock, 1)) {
while(*lock) {
}
}
return 0;
}
static force_inline int ast_spinlock_trylock(ast_spinlock_t *lock)
{
return x86chgl(lock, 1);
}
static force_inline int ast_spinlock_unlock(ast_spinlock_t *lock)
{
x86chgl(lock, 0);
return 0;
}
static force_inline int ast_spinlock_destroy(ast_spinlock_t *lock)
{
return 0;
}
#endif
/*!
* \brief Implementation using ARM Assembly
*
* For ARM implementations that don't support gcc atomics,
* this is the next best method.
*
*/
#if defined(__arm__) && !defined(AST_SPINLOCK_TYPE)
#define AST_SPINLOCK_TYPE AST_SPINLOCK_TYPE_GAS_ARM
#define AST_SPINLOCK_TYPE_LABEL "gas_arm"
typedef volatile unsigned int ast_spinlock_t;
static force_inline int ast_spinlock_init(ast_spinlock_t *lock)
{
*lock = 0;
return 0;
}
static force_inline int ast_spinlock_lock(ast_spinlock_t *lock)
{
unsigned int tmp;
__asm __volatile (
"1: ldrex %[tmp], %[lock];"
" teq %[tmp], #0;"
#if defined __ARM_ARCH && __ARM_ARCH >= 7
" wfene;"
#endif
" strexeq %[tmp], %[c1], %[lock];"
" teqeq %[tmp], #0;"
" bne 1b;"
: [tmp] "=&r" (tmp)
: [lock] "m" (*lock) [c1] "r" (1)
: "cc"
);
return tmp;
}
static force_inline int ast_spinlock_trylock(ast_spinlock_t *lock)
{
unsigned int tmp;
__asm __volatile (
" ldrex %[tmp], %[lock];"
" teq %[tmp], #0;"
#if defined __ARM_ARCH && __ARM_ARCH >= 7
" wfene;"
#endif
" strexeq %[tmp], %[c1], %[lock];"
: [tmp] "=&r" (tmp)
: [lock] "m" (*lock) [c1] "r" (1)
: "cc"
);
return tmp;
}
static force_inline int ast_spinlock_unlock(ast_spinlock_t *lock)
{
__asm __volatile (
" dmb;"
" str %[c0], %[lock];"
#if defined __ARM_ARCH && __ARM_ARCH >= 7
" dsb;"
" sev;"
#endif
:
: [lock] "m" (*lock) [c0] "r" (0)
: "cc"
);
return 0;
}
static force_inline int ast_spinlock_destroy(ast_spinlock_t *lock)
{
return 0;
}
#endif
/*!
* \brief Implementation using Sparc Assembly
*
* For Sparc implementations that don't support gcc atomics,
* this is the next best method.
*
*/
#if defined(__sparc__) && !defined(AST_SPINLOCK_TYPE)
#define AST_SPINLOCK_TYPE AST_SPINLOCK_TYPE_GAS_SPARC
#define AST_SPINLOCK_TYPE_LABEL "gas_sparc"
typedef volatile unsigned char ast_spinlock_t;
static force_inline int ast_spinlock_init(ast_spinlock_t *lock)
{
*lock = 0;
return 0;
}
static force_inline int ast_spinlock_lock(ast_spinlock_t *lock)
{
unsigned char tmp;
__asm__ __volatile__(
"1: ldstub %[lock], %[tmp]\n"
" brnz,pn %[tmp], 2f\n"
" nop\n"
" .subsection 2\n"
"2: ldub %[lock], %[tmp]\n"
" brnz,pt %[tmp], 2b\n"
" nop\n"
" ba,a,pt %%xcc, 1b\n"
" .previous"
: [tmp] "=&r" (tmp)
: [lock] "m" (*lock)
: "memory"
);
return 0;
}
static force_inline int ast_spinlock_trylock(ast_spinlock_t *lock)
{
unsigned long result = 1;
__asm__ __volatile__(
" ldstub %[lock], %[result]\n"
: [result] "=&r" (result)
: [lock] "m" (*lock)
: "memory", "cc"
);
return (result != 0);
}
static force_inline int ast_spinlock_unlock(ast_spinlock_t *lock)
{
__asm__ __volatile__(
" stb %%g0, %[lock]"
:
: [lock] "m" (*lock)
: "memory", "cc"
);
return 0;
}
static force_inline int ast_spinlock_destroy(ast_spinlock_t *lock)
{
return 0;
}
#endif
/*!
* \brief Implementation using pthread_spinlock
*
* pthread_spinlocks are not supported on all platforms
* but if for some reason none of the previous implementations are
* available, it can be used with reasonable performance.
*
*/
#if defined (HAVE_PTHREAD_SPINLOCK) && !defined(AST_SPINLOCK_TYPE)
#define AST_SPINLOCK_TYPE AST_SPINLOCK_TYPE_PTHREAD_SPINLOCK
#define AST_SPINLOCK_TYPE_LABEL "pthread_spinlock"
typedef pthread_spinlock_t ast_spinlock_t;
static force_inline int ast_spinlock_init(ast_spinlock_t *lock)
{
return pthread_spin_init(lock, PTHREAD_PROCESS_PRIVATE);
}
static force_inline int ast_spinlock_lock(ast_spinlock_t *lock)
{
return pthread_spin_lock(lock);
}
static force_inline int ast_spinlock_trylock(ast_spinlock_t *lock)
{
return pthread_spin_trylock(lock);
}
static force_inline int ast_spinlock_unlock(ast_spinlock_t *lock)
{
return pthread_spin_unlock(lock);
}
static force_inline int ast_spinlock_destroy(ast_spinlock_t *lock)
{
return pthread_spin_destroy(lock);
}
#endif
/*!
* \brief Implementation using OSX Atomics
*
* The Darwin/Mac OSX platform has its own atomics
* implementation but it uses more kernel time than
* GCC atomics and x86 assembly. It is included
* as an unlikely fallback.
*
*/
#if defined(HAVE_OSX_ATOMICS) && !defined(AST_SPINLOCK_TYPE)
#include <libkern/OSAtomic.h>
#define AST_SPINLOCK_TYPE AST_SPINLOCK_TYPE_OSX_ATOMICS
#define AST_SPINLOCK_TYPE_LABEL "osx_atomics"
typedef OSSpinLock ast_spinlock_t;
static force_inline int ast_spinlock_init(ast_spinlock_t *lock)
{
*lock = OS_SPINLOCK_INIT;
return 0;
}
static force_inline int ast_spinlock_lock(ast_spinlock_t *lock)
{
OSSpinLockLock(lock);
return 0;
}
static force_inline int ast_spinlock_trylock(ast_spinlock_t *lock)
{
return !OSSpinLockTry(lock);
}
static force_inline int ast_spinlock_unlock(ast_spinlock_t *lock)
{
OSSpinLockUnlock(lock);
return 0;
}
static force_inline int ast_spinlock_destroy(ast_spinlock_t *lock)
{
return 0;
}
#endif
/*!
* \brief Implementation using pthread_mutex
*
* pthread_mutex is supported on all platforms but
* it is also the worst performing. It is included
* as an unlikely fallback.
*
*/
#if !defined(AST_SPINLOCK_TYPE)
#define AST_SPINLOCK_TYPE AST_SPINLOCK_TYPE_PTHREAD_MUTEX
#define AST_SPINLOCK_TYPE_LABEL "pthread_mutex"
typedef pthread_mutex_t ast_spinlock_t;
static force_inline int ast_spinlock_init(ast_spinlock_t *lock)
{
pthread_mutex_init(lock, NULL);
return 0;
}
static force_inline int ast_spinlock_lock(ast_spinlock_t *lock)
{
return pthread_mutex_lock(lock);
}
static force_inline int ast_spinlock_trylock(ast_spinlock_t *lock)
{
return pthread_mutex_trylock(lock);
}
static force_inline int ast_spinlock_unlock(ast_spinlock_t *lock)
{
return pthread_mutex_unlock(lock);
}
static force_inline int ast_spinlock_destroy(ast_spinlock_t *lock)
{
return pthread_mutex_destroy(lock);
}
#endif
#if !defined(AST_SPINLOCK_TYPE)
#error "No spinlock implementation could be found."
#endif
/* Prototypes are declared here to insure that each implementation provides
* the same API and to act as placeholders for the documentation.
*/
/*!
* \brief Initialize a spin lock
* \param lock Address of the lock
* \retval 0 Success
* \retval other Failure
*/
static force_inline int ast_spinlock_init(ast_spinlock_t *lock);
/*!
* \brief Lock a spin lock
* \param lock Address of the lock
* \retval 0 Success
* \retval other Failure
*/
static force_inline int ast_spinlock_lock(ast_spinlock_t *lock);
/*!
* \brief Try to lock a spin lock
*
* Attempt to gain a lock. Return immediately
* regardless of result.
*
* \param lock Address of the lock
* \retval 0 Success
* \retval other Lock was not obtained
*/
static force_inline int ast_spinlock_trylock(ast_spinlock_t *lock);
/*!
* \brief Unlock a spin lock
* \param lock Address of the lock
* \retval 0 Success
* \retval other Failure
*/
static force_inline int ast_spinlock_unlock(ast_spinlock_t *lock);
/*!
* \brief Destroy a spin lock
* \param lock Address of the lock
* \retval 0 Success
* \retval other Failure
*/
static force_inline int ast_spinlock_destroy(ast_spinlock_t *lock);
#endif /* _ASTERISK_SPINLOCK_H */
|