Blame nptl/lowlevellock.c

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/* low level locking for pthread library.  Generic futex-using version.
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   Copyright (C) 2003-2018 Free Software Foundation, Inc.
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   This file is part of the GNU C Library.
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   Contributed by Paul Mackerras <paulus@au.ibm.com>, 2003.
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   The GNU C Library is free software; you can redistribute it and/or
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   modify it under the terms of the GNU Lesser General Public
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   License as published by the Free Software Foundation; either
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   version 2.1 of the License, or (at your option) any later version.
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   The GNU C Library is distributed in the hope that it will be useful,
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   but WITHOUT ANY WARRANTY; without even the implied warranty of
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   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
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   Lesser General Public License for more details.
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   You should have received a copy of the GNU Lesser General Public
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   License along with the GNU C Library; if not, see
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   <http://www.gnu.org/licenses/>.  */
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#include <errno.h>
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#include <sysdep.h>
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#include <lowlevellock.h>
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#include <sys/time.h>
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#include <atomic.h>
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void
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__lll_lock_wait_private (int *futex)
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{
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  if (*futex == 2)
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    lll_futex_wait (futex, 2, LLL_PRIVATE); /* Wait if *futex == 2.  */
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  while (atomic_exchange_acq (futex, 2) != 0)
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    lll_futex_wait (futex, 2, LLL_PRIVATE); /* Wait if *futex == 2.  */
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}
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/* This function doesn't get included in libc.  */
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#if IS_IN (libpthread)
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void
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__lll_lock_wait (int *futex, int private)
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{
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  if (*futex == 2)
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    lll_futex_wait (futex, 2, private); /* Wait if *futex == 2.  */
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  while (atomic_exchange_acq (futex, 2) != 0)
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    lll_futex_wait (futex, 2, private); /* Wait if *futex == 2.  */
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}
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#endif