ports/sysdeps/unix/sysv/linux/hppa/nptl/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
  25 void
  26 __lll_lock_wait (lll_lock_t *futex, int private)
  27 {
  28   do
  29     {
  30       int oldval = atomic_compare_and_exchange_val_acq (futex, 2, 1);
  31       if (oldval != 0)
  32         lll_futex_wait (futex, 2, private);
  33     }
  34   while (atomic_compare_and_exchange_val_acq (futex, 2, 0) != 0);
  35 }
  36
  37 void
  38 __lll_lock_wait_private (lll_lock_t *futex)
  39 {
  40   do
  41     {
  42       int oldval = atomic_compare_and_exchange_val_acq (futex, 2, 1);
  43       if (oldval != 0)
  44         lll_futex_wait (futex, 2, LLL_PRIVATE);
  45     }
  46   while (atomic_compare_and_exchange_val_acq (futex, 2, 0) != 0);
  47 }
  48
  49 int
  50 __lll_timedlock_wait (lll_lock_t *futex, const struct timespec *abstime, int private)
  51 {
  52   /* Reject invalid timeouts.  */
  53   if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000)
  54     return EINVAL;
  55
  56   do
  57     {
  58       struct timeval tv;
  59       struct timespec rt;
  60
  61       /* Get the current time.  */
  62       (void) __gettimeofday (&tv, NULL);
  63
  64       /* Compute relative timeout.  */
  65       rt.tv_sec = abstime->tv_sec - tv.tv_sec;
  66       rt.tv_nsec = abstime->tv_nsec - tv.tv_usec * 1000;
  67       if (rt.tv_nsec < 0)
  68         {
  69           rt.tv_nsec += 1000000000;
  70           --rt.tv_sec;
  71         }
  72
  73       /* Already timed out?  */
  74       if (rt.tv_sec < 0)
  75         return ETIMEDOUT;
  76
  77       /* Wait.  */
  78       int oldval = atomic_compare_and_exchange_val_acq (futex, 2, 1);
  79       if (oldval != 0)
  80         lll_futex_timed_wait (futex, 2, &rt, private);
  81     }
  82   while (atomic_compare_and_exchange_bool_acq (futex, 2, 0) != 0);
  83   return 0;
  84 }
  85
  86
  87 /* These don't get included in libc.so  */
  88 #ifdef IS_IN_libpthread
  89 int
  90 lll_unlock_wake_cb (lll_lock_t *futex)
  91 {
  92   int val = atomic_exchange_rel (futex, 0);
  93
  94   if (__builtin_expect (val > 1, 0))
  95     lll_private_futex_wake (futex, 1);
  96   return 0;
  97 }
  98
  99
 100 int
 101 __lll_timedwait_tid (int *tidp, const struct timespec *abstime)
 102 {
 103   int tid;
 104
 105   if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000)
 106     return EINVAL;
 107
 108   /* Repeat until thread terminated.  */
 109   while ((tid = *tidp) != 0)
 110     {
 111       struct timeval tv;
 112       struct timespec rt;
 113
 114       /* Get the current time.  */
 115       (void) __gettimeofday (&tv, NULL);
 116
 117       /* Compute relative timeout.  */
 118       rt.tv_sec = abstime->tv_sec - tv.tv_sec;
 119       rt.tv_nsec = abstime->tv_nsec - tv.tv_usec * 1000;
 120       if (rt.tv_nsec < 0)
 121         {
 122           rt.tv_nsec += 1000000000;
 123           --rt.tv_sec;
 124         }
 125
 126       /* Already timed out?  */
 127       if (rt.tv_sec < 0)
 128         return ETIMEDOUT;
 129
 130       /* Wait until thread terminates.  */
 131       if (lll_futex_timed_wait (tidp, tid, &rt, LLL_SHARED) == -ETIMEDOUT)
 132         return ETIMEDOUT;
 133     }
 134
 135   return 0;
 136 }
 137
 138 #endif
 139