db_events.c 4.5 KB

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  1. /* -*- mode:c; c-file-style:"k&r"; c-basic-offset: 4; tab-width:4; indent-tabs-mode:nil; mode:auto-fill; fill-column:78; -*- */
  2. /* vim: set ts=4 sw=4 et tw=78 fo=cqt wm=0: */
  3. /* Copyright (C) 2014 Stony Brook University
  4. This file is part of Graphene Library OS.
  5. Graphene Library OS is free software: you can redistribute it and/or
  6. modify it under the terms of the GNU Lesser General Public License
  7. as published by the Free Software Foundation, either version 3 of the
  8. License, or (at your option) any later version.
  9. Graphene Library OS is distributed in the hope that it will be useful,
  10. but WITHOUT ANY WARRANTY; without even the implied warranty of
  11. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  12. GNU Lesser General Public License for more details.
  13. You should have received a copy of the GNU Lesser General Public License
  14. along with this program. If not, see <http://www.gnu.org/licenses/>. */
  15. /*
  16. * db_event.c
  17. *
  18. * This file contains implementation of Drawbridge event synchronization APIs.
  19. */
  20. #include "pal_defs.h"
  21. #include "pal_linux_defs.h"
  22. #include "pal.h"
  23. #include "pal_internal.h"
  24. #include "pal_linux.h"
  25. #include "pal_error.h"
  26. #include "pal_debug.h"
  27. #include "api.h"
  28. #include <atomic.h>
  29. #include <linux/futex.h>
  30. #include <linux/time.h>
  31. int _DkEventCreate (PAL_HANDLE * event, bool initialState, bool isnotification)
  32. {
  33. PAL_HANDLE ev = malloc(HANDLE_SIZE(event));
  34. SET_HANDLE_TYPE(ev, event);
  35. ev->event.isnotification = isnotification;
  36. ev->event.signaled = malloc_untrusted(sizeof(struct atomic_int));
  37. if (!ev->event.signaled) {
  38. free(ev);
  39. return -PAL_ERROR_NOMEM;
  40. }
  41. atomic_set(ev->event.signaled, initialState ? 1 : 0);
  42. atomic_set(&ev->event.nwaiters, 0);
  43. *event = ev;
  44. return 0;
  45. }
  46. int _DkEventSet (PAL_HANDLE event, int wakeup)
  47. {
  48. int ret = 0;
  49. if (event->event.isnotification) {
  50. // Leave it signaled, wake all
  51. if (atomic_cmpxchg(event->event.signaled, 0, 1) == 0) {
  52. int nwaiters = atomic_read(&event->event.nwaiters);
  53. if (nwaiters) {
  54. if (wakeup != -1 && nwaiters > wakeup)
  55. nwaiters = wakeup;
  56. ret = ocall_futex((int *) &event->event.signaled->counter,
  57. FUTEX_WAKE, nwaiters, NULL);
  58. if (ret < 0)
  59. atomic_set(event->event.signaled, 0);
  60. }
  61. }
  62. } else {
  63. // Only one thread wakes up, leave unsignaled
  64. ret = ocall_futex((int *) &event->event.signaled->counter,
  65. FUTEX_WAKE, 1, NULL);
  66. if (ret < 0)
  67. return ret;
  68. }
  69. return ret;
  70. }
  71. int _DkEventWaitTimeout (PAL_HANDLE event, uint64_t timeout)
  72. {
  73. int ret = 0;
  74. if (!event->event.isnotification || !atomic_read(event->event.signaled)) {
  75. unsigned long waittime = timeout;
  76. atomic_inc(&event->event.nwaiters);
  77. do {
  78. ret = ocall_futex((int *) &event->event.signaled->counter,
  79. FUTEX_WAIT, 0, timeout ? &waittime : NULL);
  80. if (ret < 0) {
  81. if (ret == -PAL_ERROR_TRYAGAIN)
  82. ret = 0;
  83. else
  84. break;
  85. }
  86. } while (event->event.isnotification &&
  87. !atomic_read(event->event.signaled));
  88. atomic_dec(&event->event.nwaiters);
  89. }
  90. return ret;
  91. }
  92. int _DkEventWait (PAL_HANDLE event)
  93. {
  94. int ret = 0;
  95. if (!event->event.isnotification || !atomic_read(event->event.signaled)) {
  96. atomic_inc(&event->event.nwaiters);
  97. do {
  98. ret = ocall_futex((int *) &event->event.signaled->counter,
  99. FUTEX_WAIT, 0, NULL);
  100. if (ret < 0) {
  101. if (ret == -PAL_ERROR_TRYAGAIN)
  102. ret = 0;
  103. else
  104. break;
  105. }
  106. } while (event->event.isnotification &&
  107. !atomic_read(event->event.signaled));
  108. atomic_dec(&event->event.nwaiters);
  109. }
  110. return ret;
  111. }
  112. int _DkEventClear (PAL_HANDLE event)
  113. {
  114. atomic_set(event->event.signaled, 0);
  115. return 0;
  116. }
  117. static int event_close (PAL_HANDLE handle)
  118. {
  119. _DkEventSet(handle, -1);
  120. free_untrusted(handle->event.signaled);
  121. return 0;
  122. }
  123. static int event_wait (PAL_HANDLE handle, uint64_t timeout)
  124. {
  125. return timeout == NO_TIMEOUT ? _DkEventWait(handle) :
  126. _DkEventWaitTimeout(handle, timeout);
  127. }
  128. struct handle_ops event_ops = {
  129. .close = &event_close,
  130. .wait = &event_wait,
  131. };