pthread_setcancelstate.c 2.2 KB

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  1. /* Copyright (C) 2002, 2003 Free Software Foundation, Inc.
  2. This file is part of the GNU C Library.
  3. Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
  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, write to the Free
  14. Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  15. 02111-1307 USA. */
  16. #include <errno.h>
  17. #include "pthreadP.h"
  18. #include <atomic.h>
  19. int
  20. __pthread_setcancelstate (
  21. int state,
  22. int *oldstate)
  23. {
  24. volatile struct pthread *self;
  25. if (state < PTHREAD_CANCEL_ENABLE || state > PTHREAD_CANCEL_DISABLE)
  26. return EINVAL;
  27. self = THREAD_SELF;
  28. int oldval = THREAD_GETMEM (self, cancelhandling);
  29. while (1)
  30. {
  31. int newval = (state == PTHREAD_CANCEL_DISABLE
  32. ? oldval | CANCELSTATE_BITMASK
  33. : oldval & ~CANCELSTATE_BITMASK);
  34. /* Store the old value. */
  35. if (oldstate != NULL)
  36. *oldstate = ((oldval & CANCELSTATE_BITMASK)
  37. ? PTHREAD_CANCEL_DISABLE : PTHREAD_CANCEL_ENABLE);
  38. /* Avoid doing unnecessary work. The atomic operation can
  39. potentially be expensive if the memory has to be locked and
  40. remote cache lines have to be invalidated. */
  41. if (oldval == newval)
  42. break;
  43. /* Update the cancel handling word. This has to be done
  44. atomically since other bits could be modified as well. */
  45. int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval,
  46. oldval);
  47. if (__builtin_expect (curval == oldval, 1))
  48. {
  49. if (CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS (newval))
  50. __do_cancel ();
  51. break;
  52. }
  53. /* Prepare for the next round. */
  54. oldval = curval;
  55. }
  56. return 0;
  57. }
  58. strong_alias (__pthread_setcancelstate, pthread_setcancelstate)