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- /* Default mutex implementation struct definitions.
- Copyright (C) 2019-2026 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/>. */
- #ifndef _THREAD_MUTEX_INTERNAL_H
- #define _THREAD_MUTEX_INTERNAL_H 1
- /* Generic struct for both POSIX and C11 mutexes. New ports are expected
- to use the default layout, however architecture can redefine it to
- add arch-specific extension. The struct have a size of 32 bytes on LP32
- and 40 bytes on LP64 architectures. */
- struct __pthread_mutex_s
- {
- int __lock __LOCK_ALIGNMENT;
- unsigned int __count;
- int __owner;
- #if __WORDSIZE == 64
- unsigned int __nusers;
- #endif
- /* KIND must stay at this position in the structure to maintain
- binary compatibility with static initializers.
- Concurrency notes:
- The __kind of a mutex is initialized either by the static
- PTHREAD_MUTEX_INITIALIZER or by a call to pthread_mutex_init.
- After a mutex has been initialized, the __kind of a mutex is usually not
- changed. BUT it can be set to -1 in pthread_mutex_destroy. */
- int __kind;
- #if __WORDSIZE != 64
- unsigned int __nusers;
- #endif
- #if __WORDSIZE == 64
- int __spins;
- __pthread_list_t __list;
- # define __PTHREAD_MUTEX_HAVE_PREV 1
- #else
- __extension__ union
- {
- int __spins;
- __pthread_slist_t __list;
- };
- # define __PTHREAD_MUTEX_HAVE_PREV 0
- #endif
- };
- #if __PTHREAD_MUTEX_HAVE_PREV == 1
- # define __PTHREAD_MUTEX_INITIALIZER(__kind) \
- 0, 0, 0, 0, __kind, 0, { 0, 0 }
- #else
- # define __PTHREAD_MUTEX_INITIALIZER(__kind) \
- 0, 0, 0, __kind, 0, { 0 }
- #endif
- #endif
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