mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-09 23:00:07 +00:00
68 lines
2.8 KiB
C
68 lines
2.8 KiB
C
/* Copyright (C) 2002-2024 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 <errno.h>
|
|
#include "pthreadP.h"
|
|
#include <atomic.h>
|
|
#include <futex-internal.h>
|
|
#include <shlib-compat.h>
|
|
|
|
int
|
|
__pthread_barrier_destroy (pthread_barrier_t *barrier)
|
|
{
|
|
struct pthread_barrier *bar = (struct pthread_barrier *) barrier;
|
|
|
|
/* Destroying a barrier is only allowed if no thread is blocked on it.
|
|
Thus, there is no unfinished round, and all modifications to IN will
|
|
have happened before us (either because the calling thread took part
|
|
in the most recent round and thus synchronized-with all other threads
|
|
entering, or the program ensured this through other synchronization).
|
|
We must wait until all threads that entered so far have confirmed that
|
|
they have exited as well. To get the notification, pretend that we have
|
|
reached the reset threshold. */
|
|
unsigned int count = bar->count;
|
|
unsigned int max_in_before_reset = BARRIER_IN_THRESHOLD
|
|
- BARRIER_IN_THRESHOLD % count;
|
|
/* Relaxed MO sufficient because the program must have ensured that all
|
|
modifications happen-before this load (see above). */
|
|
unsigned int in = atomic_load_relaxed (&bar->in);
|
|
/* Trigger reset. The required acquire MO is below. */
|
|
if (atomic_fetch_add_relaxed (&bar->out, max_in_before_reset - in) < in)
|
|
{
|
|
/* Not all threads confirmed yet that they have exited, so another
|
|
thread will perform a reset. Wait until that has happened. */
|
|
while (in != 0)
|
|
{
|
|
futex_wait_simple (&bar->in, in, bar->shared);
|
|
in = atomic_load_relaxed (&bar->in);
|
|
}
|
|
}
|
|
/* We must ensure that memory reuse happens after all prior use of the
|
|
barrier (specifically, synchronize-with the reset of the barrier or the
|
|
confirmation of threads leaving the barrier). */
|
|
atomic_thread_fence_acquire ();
|
|
|
|
return 0;
|
|
}
|
|
versioned_symbol (libc, __pthread_barrier_destroy, pthread_barrier_destroy,
|
|
GLIBC_2_34);
|
|
|
|
#if OTHER_SHLIB_COMPAT (libpthread, GLIBC_2_2, GLIBC_2_34)
|
|
compat_symbol (libpthread, __pthread_barrier_destroy, pthread_barrier_destroy,
|
|
GLIBC_2_2);
|
|
#endif
|