nptl/sysdeps/unix/sysv/linux/lowlevelrobustlock.c

   1 /* Copyright (C) 2006 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Jakub Jelinek <jakub@redhat.com>, 2006.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <errno.h>
  21 #include <sysdep.h>
  22 #include <lowlevellock.h>
  23 #include <sys/time.h>
  24 #include <pthreadP.h>
  25
  26
  27 int
  28 __lll_robust_lock_wait (int *futex)
  29 {
  30   int oldval = *futex;
  31   int tid = THREAD_GETMEM (THREAD_SELF, tid);
  32
  33   do
  34     {
  35       if (__builtin_expect (oldval & FUTEX_OWNER_DIED, 0))
  36         return oldval;
  37
  38       int newval = oldval | FUTEX_WAITERS;
  39       if (oldval != newval
  40           && atomic_compare_and_exchange_bool_acq (futex, newval, oldval))
  41         continue;
  42
  43       lll_futex_wait (futex, newval);
  44     }
  45   while ((oldval = atomic_compare_and_exchange_val_acq (futex,
  46                                                         tid | FUTEX_WAITERS,
  47                                                         0)) != 0);
  48   return 0;
  49 }
  50
  51
  52 int
  53 __lll_robust_timedlock_wait (int *futex, const struct timespec *abstime)
  54 {
  55   /* Reject invalid timeouts.  */
  56   if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000)
  57     return EINVAL;
  58
  59   int tid = THREAD_GETMEM (THREAD_SELF, tid);
  60
  61   do
  62     {
  63       struct timeval tv;
  64       struct timespec rt;
  65
  66       /* Get the current time.  */
  67       (void) __gettimeofday (&tv, NULL);
  68
  69       /* Compute relative timeout.  */
  70       rt.tv_sec = abstime->tv_sec - tv.tv_sec;
  71       rt.tv_nsec = abstime->tv_nsec - tv.tv_usec * 1000;
  72       if (rt.tv_nsec < 0)
  73         {
  74           rt.tv_nsec += 1000000000;
  75           --rt.tv_sec;
  76         }
  77
  78       /* Already timed out?  */
  79       if (rt.tv_sec < 0)
  80         return ETIMEDOUT;
  81
  82       /* Wait.  */
  83       int oldval = *futex;
  84       if (__builtin_expect (oldval & FUTEX_OWNER_DIED, 0))
  85         return oldval;
  86
  87       int newval = oldval | FUTEX_WAITERS;
  88       if (oldval != newval
  89           && atomic_compare_and_exchange_bool_acq (futex, newval, oldval))
  90         continue;
  91
  92       lll_futex_timed_wait (futex, newval, &rt);
  93     }
  94   while (atomic_compare_and_exchange_bool_acq (futex, tid | FUTEX_WAITERS, 0));
  95
  96   return 0;
  97 }