glibc/sysdeps/htl/dl-thread_gscope_wait.c

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/* Out-of-line notification function for the GSCOPE locking mechanism.
Copyright (C) 2007-2024 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 <ldsodefs.h>
#include <pthread.h>
#include <htl/pt-internal.h>
void
__thread_gscope_wait (void)
{
size_t i;
struct __pthread *t;
int *gscope_flagp;
__libc_rwlock_rdlock (GL (dl_pthread_threads_lock));
/* Iterate over the list of threads. */
for (i = 0; i < GL (dl_pthread_num_threads); ++i)
{
t = GL (dl_pthread_threads[i]);
if (t == NULL || t->tcb->gscope_flag == THREAD_GSCOPE_FLAG_UNUSED)
continue;
gscope_flagp = &t->tcb->gscope_flag;
/* We have to wait until this thread is done with the global
scope. First tell the thread that we are waiting and
possibly have to be woken. */
if (atomic_compare_and_exchange_bool_acq (gscope_flagp,
THREAD_GSCOPE_FLAG_WAIT,
THREAD_GSCOPE_FLAG_USED))
continue;
do
lll_wait (gscope_flagp, THREAD_GSCOPE_FLAG_WAIT, LLL_PRIVATE);
while (*gscope_flagp == THREAD_GSCOPE_FLAG_WAIT);
}
__libc_rwlock_unlock (GL (dl_pthread_threads_lock));
}