diff options
Diffstat (limited to 'libpthread/nptl/sysdeps/unix/sysv/linux/kvx/pthread_once.c')
-rw-r--r-- | libpthread/nptl/sysdeps/unix/sysv/linux/kvx/pthread_once.c | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/libpthread/nptl/sysdeps/unix/sysv/linux/kvx/pthread_once.c b/libpthread/nptl/sysdeps/unix/sysv/linux/kvx/pthread_once.c new file mode 100644 index 000000000..0d2749edf --- /dev/null +++ b/libpthread/nptl/sysdeps/unix/sysv/linux/kvx/pthread_once.c @@ -0,0 +1,77 @@ +/* + * 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) |