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author | Torvald Riegel <triegel@redhat.com> | 2013-05-08 16:35:10 +0200 |
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committer | Torvald Riegel <triegel@redhat.com> | 2014-04-11 15:54:19 +0200 |
commit | 36875b06e0ed7f137190b9228bef553adfc338ba (patch) | |
tree | 347e3826873e48eb6433e6d09666d7cef8904766 /sysdeps/unix/sysv/linux/aarch64/nptl/pthread_once.c | |
parent | 579db35a068e70a4f3112000778138ede6994ac0 (diff) | |
download | glibc-36875b06e0ed7f137190b9228bef553adfc338ba.tar.gz glibc-36875b06e0ed7f137190b9228bef553adfc338ba.tar.xz glibc-36875b06e0ed7f137190b9228bef553adfc338ba.zip |
Fixed and unified pthread_once.
[BZ #15215] This unifies various pthread_once architecture-specific implementations which were using the same algorithm with slightly different implementations. It also adds missing memory barriers that are required for correctness.
Diffstat (limited to 'sysdeps/unix/sysv/linux/aarch64/nptl/pthread_once.c')
-rw-r--r-- | sysdeps/unix/sysv/linux/aarch64/nptl/pthread_once.c | 90 |
1 files changed, 0 insertions, 90 deletions
diff --git a/sysdeps/unix/sysv/linux/aarch64/nptl/pthread_once.c b/sysdeps/unix/sysv/linux/aarch64/nptl/pthread_once.c deleted file mode 100644 index d1b28ff51f..0000000000 --- a/sysdeps/unix/sysv/linux/aarch64/nptl/pthread_once.c +++ /dev/null @@ -1,90 +0,0 @@ -/* Copyright (C) 2004-2014 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 - <http://www.gnu.org/licenses/>. */ - -#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 (pthread_once_t *once_control, void (*init_routine) (void)) -{ - for (;;) - { - int oldval; - int newval; - - /* Pseudo code: - newval = __fork_generation | 1; - oldval = *once_control; - if ((oldval & 2) == 0) - *once_control = newval; - Do this atomically. - */ - do - { - newval = __fork_generation | 1; - oldval = *once_control; - if (oldval & 2) - break; - } while (atomic_compare_and_exchange_val_acq (once_control, newval, oldval) != oldval); - - /* Check if the initializer has already been done. */ - if ((oldval & 2) != 0) - return 0; - - /* Check if another thread already runs the initializer. */ - if ((oldval & 1) == 0) - break; - - /* Check whether the initializer execution was interrupted by a fork. */ - if (oldval != newval) - break; - - /* Same generation, some other thread was faster. Wait. */ - lll_futex_wait (once_control, oldval, LLL_PRIVATE); - } - - /* 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); - - /* Say that the initialisation is done. */ - *once_control = __fork_generation | 2; - - /* Wake up all other threads. */ - lll_futex_wake (once_control, INT_MAX, LLL_PRIVATE); - - return 0; -} -weak_alias (__pthread_once, pthread_once) -hidden_def (__pthread_once) |