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/* Out-of-line notification function for the GSCOPE locking mechanism.
Copyright (C) 2007-2021 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 <nptl/descr.h>
#include <futex-internal.h>
#include <ldsodefs.h>
#include <list.h>
#include <lowlevellock.h>
void
__thread_gscope_wait (void)
{
lll_lock (GL (dl_stack_cache_lock), LLL_PRIVATE);
struct pthread *self = THREAD_SELF;
/* Iterate over the list with system-allocated threads first. */
list_t *runp;
list_for_each (runp, &GL (dl_stack_used))
{
struct pthread *t = list_entry (runp, struct pthread, list);
if (t == self || t->header.gscope_flag == THREAD_GSCOPE_FLAG_UNUSED)
continue;
int *const gscope_flagp = &t->header.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
futex_wait_simple ((unsigned int *) gscope_flagp,
THREAD_GSCOPE_FLAG_WAIT, FUTEX_PRIVATE);
while (*gscope_flagp == THREAD_GSCOPE_FLAG_WAIT);
}
/* Now the list with threads using user-allocated stacks. */
list_for_each (runp, &GL (dl_stack_user))
{
struct pthread *t = list_entry (runp, struct pthread, list);
if (t == self || t->header.gscope_flag == THREAD_GSCOPE_FLAG_UNUSED)
continue;
int *const gscope_flagp = &t->header.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
futex_wait_simple ((unsigned int *) gscope_flagp,
THREAD_GSCOPE_FLAG_WAIT, FUTEX_PRIVATE);
while (*gscope_flagp == THREAD_GSCOPE_FLAG_WAIT);
}
lll_unlock (GL (dl_stack_cache_lock), LLL_PRIVATE);
}
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