libpthread/nptl/sysdeps/unix/sysv/linux/arc/lowlevellock.c

   1 /* low level locking for pthread library.  Generic futex-using version.
   2    Copyright (C) 2003, 2007 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Paul Mackerras <paulus@au.ibm.com>, 2003.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <errno.h>
  21 #include <sysdep.h>
  22 #include <lowlevellock.h>
  23 #include <sys/time.h>
  24 #include <tls.h>
  25 #include <tcb-offsets.h>
  26
  27 void
  28 #ifndef IS_IN_libpthread
  29 weak_function
  30 #endif
  31 __lll_lock_wait_private (int *futex)
  32 {
  33   if (*futex == 2)
  34     lll_futex_wait (futex, 2, LLL_PRIVATE);
  35
  36   while (atomic_exchange_acq (futex, 2) != 0)
  37     lll_futex_wait (futex, 2, LLL_PRIVATE);
  38 }
  39
  40
  41 /* These functions don't get included in libc.so  */
  42 #ifdef IS_IN_libpthread
  43 void
  44 __lll_lock_wait (int *futex, int private)
  45 {
  46   if (*futex == 2)
  47     lll_futex_wait (futex, 2, private);
  48
  49   while (atomic_exchange_acq (futex, 2) != 0)
  50     lll_futex_wait (futex, 2, private);
  51 }
  52
  53
  54 int
  55 __lll_timedlock_wait (int *futex, const struct timespec *abstime, int private)
  56 {
  57   /* Reject invalid timeouts.  */
  58   if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000)
  59     return EINVAL;
  60
  61   /* Try locking.  */
  62   while (atomic_exchange_acq (futex, 2) != 0)
  63     {
  64       struct timeval tv;
  65
  66       /* Get the current time.  */
  67       (void) gettimeofday (&tv, NULL);
  68
  69       /* Compute relative timeout.  */
  70       struct timespec rt;
  71       rt.tv_sec = abstime->tv_sec - tv.tv_sec;
  72       rt.tv_nsec = abstime->tv_nsec - tv.tv_usec * 1000;
  73       if (rt.tv_nsec < 0)
  74         {
  75           rt.tv_nsec += 1000000000;
  76           --rt.tv_sec;
  77         }
  78
  79       if (rt.tv_sec < 0)
  80         return ETIMEDOUT;
  81
  82       /* Wait.  */
  83       lll_futex_timed_wait (futex, 2, &rt, private);
  84     }
  85
  86   return 0;
  87 }
  88
  89
  90 int
  91 __lll_timedwait_tid (int *tidp, const struct timespec *abstime)
  92 {
  93   int tid;
  94
  95   if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000)
  96     return EINVAL;
  97
  98   /* Repeat until thread terminated.  */
  99   while ((tid = *tidp) != 0)
 100     {
 101       struct timeval tv;
 102       struct timespec rt;
 103
 104       /* Get the current time.  */
 105       (void) __gettimeofday (&tv, NULL);
 106
 107       /* Compute relative timeout.  */
 108       rt.tv_sec = abstime->tv_sec - tv.tv_sec;
 109       rt.tv_nsec = abstime->tv_nsec - tv.tv_usec * 1000;
 110       if (rt.tv_nsec < 0)
 111         {
 112           rt.tv_nsec += 1000000000;
 113           --rt.tv_sec;
 114         }
 115
 116       /* Already timed out?  */
 117       if (rt.tv_sec < 0)
 118         return ETIMEDOUT;
 119
 120       /* Wait until thread terminates.  The kernel so far does not use
 121          the private futex operations for this.  */
 122       if (lll_futex_timed_wait (tidp, tid, &rt, LLL_SHARED) == -ETIMEDOUT)
 123         return ETIMEDOUT;
 124     }
 125
 126   return 0;
 127 }
 128 #endif