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- /*
- * This file is subject to the terms and conditions of the LGPL V2.1
- * License. See the file "COPYING" in the main directory of this archive
- * for more details.
- *
- * Copyright (C) 2019 Kalray Inc.
- */
- #include "pthreadP.h"
- #include <lowlevellock.h>
- unsigned long int __fork_generation attribute_hidden;
- static void
- clear_once_control (void *arg)
- {
- pthread_once_t *once_control = (pthread_once_t *) arg;
- *once_control = 0;
- lll_futex_wake (once_control, INT_MAX, LLL_PRIVATE);
- }
- int
- __pthread_once (once_control, init_routine)
- pthread_once_t *once_control;
- void (*init_routine) (void);
- {
- while (1)
- {
- int oldval, val, newval;
- val = *once_control;
- do
- {
- /* Check if the initialized has already been done. */
- if ((val & 2) != 0)
- return 0;
- oldval = val;
- newval = (oldval & 3) | __fork_generation | 1;
- val = atomic_compare_and_exchange_val_acq (once_control, newval, oldval);
- } while (__builtin_expect (val != oldval, 0));
- /* Check if another thread already runs the initializer. */
- if ((oldval & 1) != 0)
- {
- /* Check whether the initializer execution was interrupted
- * by a fork. */
- if (((oldval ^ newval) & -4) == 0)
- {
- /* Same generation, some other thread was faster. Wait. */
- lll_futex_wait (once_control, newval, LLL_PRIVATE);
- continue;
- }
- }
- /* This thread is the first here. Do the initialization.
- * Register a cleanup handler so that in case the thread gets
- * interrupted the initialization can be restarted. */
- pthread_cleanup_push (clear_once_control, once_control);
- init_routine ();
- pthread_cleanup_pop (0);
- /* Add one to *once_control. */
- atomic_increment (once_control);
- /* Wake up all other threads. */
- lll_futex_wake (once_control, INT_MAX, LLL_PRIVATE);
- break;
- }
- return 0;
- }
- weak_alias (__pthread_once, pthread_once)
- strong_alias (__pthread_once, __pthread_once_internal)
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