lowlevellock.c 3.4 KB

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  1. /* low level locking for pthread library. Generic futex-using version.
  2. Copyright (C) 2003, 2005, 2007 Free Software Foundation, Inc.
  3. This file is part of the GNU C Library.
  4. The GNU C Library is free software; you can redistribute it and/or
  5. modify it under the terms of the GNU Lesser General Public
  6. License as published by the Free Software Foundation; either
  7. version 2.1 of the License, or (at your option) any later version.
  8. The GNU C Library is distributed in the hope that it will be useful,
  9. but WITHOUT ANY WARRANTY; without even the implied warranty of
  10. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  11. Lesser General Public License for more details.
  12. You should have received a copy of the GNU Lesser General Public
  13. License along with the GNU C Library; if not, see
  14. <http://www.gnu.org/licenses/>. */
  15. #include <errno.h>
  16. #include <sysdep.h>
  17. #include <lowlevellock.h>
  18. #include <sys/time.h>
  19. #include <tls.h>
  20. void
  21. #ifndef IS_IN_libpthread
  22. weak_function
  23. #endif
  24. __lll_lock_wait_private (int *futex)
  25. {
  26. do
  27. {
  28. int oldval = atomic_compare_and_exchange_val_acq (futex, 2, 1);
  29. if (oldval != 0)
  30. lll_futex_wait (futex, 2, LLL_PRIVATE);
  31. }
  32. while (atomic_compare_and_exchange_bool_acq (futex, 2, 0) != 0);
  33. }
  34. /* These functions don't get included in libc.so */
  35. #ifdef IS_IN_libpthread
  36. void
  37. __lll_lock_wait (int *futex, int private)
  38. {
  39. do
  40. {
  41. int oldval = atomic_compare_and_exchange_val_acq (futex, 2, 1);
  42. if (oldval != 0)
  43. lll_futex_wait (futex, 2, private);
  44. }
  45. while (atomic_compare_and_exchange_bool_acq (futex, 2, 0) != 0);
  46. }
  47. int
  48. __lll_timedlock_wait (int *futex, const struct timespec *abstime, int private)
  49. {
  50. struct timespec rt;
  51. /* Reject invalid timeouts. */
  52. if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000)
  53. return EINVAL;
  54. /* Upgrade the lock. */
  55. if (atomic_exchange_acq (futex, 2) == 0)
  56. return 0;
  57. do
  58. {
  59. struct timeval tv;
  60. /* Get the current time. */
  61. (void) gettimeofday (&tv, NULL);
  62. /* Compute relative timeout. */
  63. rt.tv_sec = abstime->tv_sec - tv.tv_sec;
  64. rt.tv_nsec = abstime->tv_nsec - tv.tv_usec * 1000;
  65. if (rt.tv_nsec < 0)
  66. {
  67. rt.tv_nsec += 1000000000;
  68. --rt.tv_sec;
  69. }
  70. /* Already timed out? */
  71. if (rt.tv_sec < 0)
  72. return ETIMEDOUT;
  73. // XYZ: Lost the lock to check whether it was private.
  74. lll_futex_timed_wait (futex, 2, &rt, private);
  75. }
  76. while (atomic_compare_and_exchange_bool_acq (futex, 2, 0) != 0);
  77. return 0;
  78. }
  79. int
  80. __lll_timedwait_tid (int *tidp, const struct timespec *abstime)
  81. {
  82. int tid;
  83. if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000)
  84. return EINVAL;
  85. /* Repeat until thread terminated. */
  86. while ((tid = *tidp) != 0)
  87. {
  88. struct timeval tv;
  89. struct timespec rt;
  90. /* Get the current time. */
  91. (void) gettimeofday (&tv, NULL);
  92. /* Compute relative timeout. */
  93. rt.tv_sec = abstime->tv_sec - tv.tv_sec;
  94. rt.tv_nsec = abstime->tv_nsec - tv.tv_usec * 1000;
  95. if (rt.tv_nsec < 0)
  96. {
  97. rt.tv_nsec += 1000000000;
  98. --rt.tv_sec;
  99. }
  100. /* Already timed out? */
  101. if (rt.tv_sec < 0)
  102. return ETIMEDOUT;
  103. /* Wait until thread terminates. */
  104. // XYZ: Lost the lock to check whether it was private.
  105. if (lll_futex_timed_wait (tidp, tid, &rt, LLL_SHARED) == -ETIMEDOUT)
  106. return ETIMEDOUT;
  107. }
  108. return 0;
  109. }
  110. #endif