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This patch combines BUSY_WAIT_NOP and atomic_delay into a new atomic_spin_nop function and adjusts all clients. The new function is put into atomic.h because what is best done in a spin loop is architecture-specific, and atomics must be used for spinning. The function name is meant to tell users that this has no effect on synchronization semantics but is a performance aid for spinning.
42 lines
1.4 KiB
C
42 lines
1.4 KiB
C
/* Low-level lock implementation. NaCl version.
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Copyright (C) 2015 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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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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#ifndef _LOWLEVELLOCK_H
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/* Everything except the exit handling is the same as the generic code. */
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# include <sysdeps/nptl/lowlevellock.h>
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/* See exit-thread.h for details. */
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# define NACL_EXITING_TID 1
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# undef lll_wait_tid
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# define lll_wait_tid(tid) \
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do { \
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__typeof (tid) __tid; \
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volatile __typeof (tid) *__tidp = &(tid); \
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while ((__tid = atomic_load_relaxed (__tidp)) != 0) \
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{ \
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if (__tid == NACL_EXITING_TID) \
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atomic_spin_nop (); \
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else \
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lll_futex_wait (__tidp, __tid, LLL_PRIVATE); \
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} \
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} while (0)
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#endif /* lowlevellock.h */
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