mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-22 13:00:06 +00:00
c8f9421298
The implementation is extremely similar to the nptl implementation, but with slight differences in the futex interface. This fixes some of BZ 25521.
56 lines
1.6 KiB
C
56 lines
1.6 KiB
C
/* Lock a semaphore if it does not require blocking. Generic version.
|
|
Copyright (C) 2005-2020 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
|
|
The GNU C Library is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU Lesser General Public
|
|
License as published by the Free Software Foundation; either
|
|
version 2.1 of the License, or (at your option) any later version.
|
|
|
|
The GNU C Library is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
Lesser General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public
|
|
License along with the GNU C Library; if not, see
|
|
<https://www.gnu.org/licenses/>. */
|
|
|
|
#include <semaphore.h>
|
|
#include <errno.h>
|
|
|
|
#include <pt-internal.h>
|
|
|
|
int
|
|
__sem_waitfast (struct new_sem *isem, int definitive_result)
|
|
{
|
|
#if __HAVE_64B_ATOMICS
|
|
uint64_t d = atomic_load_relaxed (&isem->data);
|
|
|
|
do
|
|
{
|
|
if ((d & SEM_VALUE_MASK) == 0)
|
|
break;
|
|
if (atomic_compare_exchange_weak_acquire (&isem->data, &d, d - 1))
|
|
/* Successful down. */
|
|
return 0;
|
|
}
|
|
while (definitive_result);
|
|
return -1;
|
|
#else
|
|
unsigned v = atomic_load_relaxed (&isem->value);
|
|
|
|
do
|
|
{
|
|
if ((v >> SEM_VALUE_SHIFT) == 0)
|
|
break;
|
|
if (atomic_compare_exchange_weak_acquire (&isem->value,
|
|
&v, v - (1 << SEM_VALUE_SHIFT)))
|
|
/* Successful down. */
|
|
return 0;
|
|
}
|
|
while (definitive_result);
|
|
return -1;
|
|
#endif
|
|
}
|