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252 lines
9.4 KiB
C
252 lines
9.4 KiB
C
/* Private libc-internal interface for mutex locks. NPTL version.
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Copyright (C) 1996-2025 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 License as
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published by the Free Software Foundation; either version 2.1 of the
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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; see the file COPYING.LIB. If
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not, see <https://www.gnu.org/licenses/>. */
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#ifndef _LIBC_LOCKP_H
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#define _LIBC_LOCKP_H 1
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#include <pthread.h>
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#define __need_NULL
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#include <stddef.h>
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/* Fortunately Linux now has a mean to do locking which is realtime
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safe without the aid of the thread library. We also need no fancy
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options like error checking mutexes etc. We only need simple
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locks, maybe recursive. This can be easily and cheaply implemented
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using futexes. We will use them everywhere except in ld.so since
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ld.so might be used on old kernels with a different libc.so. */
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#include <lowlevellock.h>
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#include <tls.h>
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#include <libc-lock-arch.h>
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/* Mutex type. */
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typedef int __libc_lock_t __LIBC_LOCK_ALIGNMENT;
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typedef struct { pthread_mutex_t mutex; } __rtld_lock_recursive_t;
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typedef pthread_rwlock_t __libc_rwlock_t;
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/* Define a lock variable NAME with storage class CLASS. The lock must be
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initialized with __libc_lock_init before it can be used (or define it
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with __libc_lock_define_initialized, below). Use `extern' for CLASS to
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declare a lock defined in another module. In public structure
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definitions you must use a pointer to the lock structure (i.e., NAME
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begins with a `*'), because its storage size will not be known outside
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of libc. */
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#define __libc_lock_define(CLASS,NAME) \
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CLASS __libc_lock_t NAME;
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#define __libc_rwlock_define(CLASS,NAME) \
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CLASS __libc_rwlock_t NAME;
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#define __rtld_lock_define_recursive(CLASS,NAME) \
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CLASS __rtld_lock_recursive_t NAME;
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/* Define an initialized lock variable NAME with storage class CLASS.
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For the C library we take a deeper look at the initializer. For
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this implementation all fields are initialized to zero. Therefore
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we don't initialize the variable which allows putting it into the
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BSS section. */
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_Static_assert (LLL_LOCK_INITIALIZER == 0, "LLL_LOCK_INITIALIZER != 0");
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#define _LIBC_LOCK_INITIALIZER LLL_LOCK_INITIALIZER
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#define __libc_lock_define_initialized(CLASS,NAME) \
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CLASS __libc_lock_t NAME;
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#define __libc_rwlock_define_initialized(CLASS,NAME) \
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CLASS __libc_rwlock_t NAME = PTHREAD_RWLOCK_INITIALIZER;
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#define __rtld_lock_define_initialized_recursive(CLASS,NAME) \
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CLASS __rtld_lock_recursive_t NAME = _RTLD_LOCK_RECURSIVE_INITIALIZER;
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#define _RTLD_LOCK_RECURSIVE_INITIALIZER \
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{PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP}
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#define __rtld_lock_initialize(NAME) \
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(void) ((NAME) = (__rtld_lock_recursive_t) _RTLD_LOCK_RECURSIVE_INITIALIZER)
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/* If we check for a weakly referenced symbol and then perform a
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normal jump to it te code generated for some platforms in case of
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PIC is unnecessarily slow. What would happen is that the function
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is first referenced as data and then it is called indirectly
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through the PLT. We can make this a direct jump. */
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#ifdef __PIC__
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# define __libc_maybe_call(FUNC, ARGS, ELSE) \
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(__extension__ ({ __typeof (FUNC) *_fn = (FUNC); \
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_fn != NULL ? (*_fn) ARGS : ELSE; }))
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#else
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# define __libc_maybe_call(FUNC, ARGS, ELSE) \
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(FUNC != NULL ? FUNC ARGS : ELSE)
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#endif
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/* All previously forwarded functions are now called directly (either
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via local call in libc, or through a __export), but __libc_ptf_call
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is still used in generic code shared with Hurd. */
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#define PTFAVAIL(NAME) 1
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#define __libc_ptf_call(FUNC, ARGS, ELSE) FUNC ARGS
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#define __libc_ptf_call_always(FUNC, ARGS) FUNC ARGS
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/* Initialize the named lock variable, leaving it in a consistent, unlocked
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state. */
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#define __libc_lock_init(NAME) ((void) ((NAME) = LLL_LOCK_INITIALIZER))
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#define __libc_rwlock_init(NAME) __pthread_rwlock_init (&(NAME), NULL)
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/* Finalize the named lock variable, which must be locked. It cannot be
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used again until __libc_lock_init is called again on it. This must be
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called on a lock variable before the containing storage is reused. */
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#define __libc_lock_fini(NAME) ((void) 0)
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#define __libc_rwlock_fini(NAME) ((void) 0)
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/* Lock the named lock variable. */
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#define __libc_lock_lock(NAME) ({ lll_lock (NAME, LLL_PRIVATE); 0; })
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#define __libc_rwlock_rdlock(NAME) __pthread_rwlock_rdlock (&(NAME))
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#define __libc_rwlock_wrlock(NAME) __pthread_rwlock_wrlock (&(NAME))
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/* Try to lock the named lock variable. */
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#define __libc_lock_trylock(NAME) lll_trylock (NAME)
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/* Unlock the named lock variable. */
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#define __libc_lock_unlock(NAME) lll_unlock (NAME, LLL_PRIVATE)
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#define __libc_rwlock_unlock(NAME) __pthread_rwlock_unlock (&(NAME))
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#if IS_IN (rtld)
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# define __rtld_lock_lock_recursive(NAME) \
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___rtld_mutex_lock (&(NAME).mutex)
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# define __rtld_lock_unlock_recursive(NAME) \
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___rtld_mutex_unlock (&(NAME).mutex)
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#else /* Not in the dynamic loader. */
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# define __rtld_lock_lock_recursive(NAME) \
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__pthread_mutex_lock (&(NAME).mutex)
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# define __rtld_lock_unlock_recursive(NAME) \
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__pthread_mutex_unlock (&(NAME).mutex)
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#endif
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/* Define once control variable. */
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#if PTHREAD_ONCE_INIT == 0
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/* Special case for static variables where we can avoid the initialization
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if it is zero. */
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# define __libc_once_define(CLASS, NAME) \
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CLASS pthread_once_t NAME
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#else
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# define __libc_once_define(CLASS, NAME) \
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CLASS pthread_once_t NAME = PTHREAD_ONCE_INIT
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#endif
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/* Call handler iff the first call. Use a local call in libc, but the
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global pthread_once symbol elsewhere. */
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#if IS_IN (libc)
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# define __libc_once(ONCE_CONTROL, INIT_FUNCTION) \
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__pthread_once (&(ONCE_CONTROL), INIT_FUNCTION)
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#else
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# define __libc_once(ONCE_CONTROL, INIT_FUNCTION) \
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pthread_once (&(ONCE_CONTROL), INIT_FUNCTION)
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#endif
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/* Get once control variable. */
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#define __libc_once_get(ONCE_CONTROL) ((ONCE_CONTROL) != PTHREAD_ONCE_INIT)
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/* __libc_cleanup_push and __libc_cleanup_pop depend on exception
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handling and stack unwinding. */
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#ifdef __EXCEPTIONS
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/* Normal cleanup handling, based on C cleanup attribute. */
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static __always_inline void
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__libc_cleanup_routine (struct __pthread_cleanup_frame *f)
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{
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if (f->__do_it)
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f->__cancel_routine (f->__cancel_arg);
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}
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# define __libc_cleanup_push(fct, arg) \
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do { \
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struct __pthread_cleanup_frame __clframe \
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__attribute__ ((__cleanup__ (__libc_cleanup_routine))) \
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= { .__cancel_routine = (fct), .__cancel_arg = (arg), \
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.__do_it = 1 };
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# define __libc_cleanup_pop(execute) \
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__clframe.__do_it = (execute); \
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} while (0)
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#endif /* __EXCEPTIONS */
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/* Register handlers to execute before and after `fork'. Note that the
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last parameter is NULL. The handlers registered by the libc are
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never removed so this is OK. */
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extern int __register_atfork (void (*__prepare) (void),
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void (*__parent) (void),
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void (*__child) (void),
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void *__dso_handle);
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/* Functions that are used by this file and are internal to the GNU C
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library. */
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extern int __pthread_mutex_init (pthread_mutex_t *__mutex,
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const pthread_mutexattr_t *__mutex_attr);
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libc_hidden_proto (__pthread_mutex_init)
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extern int __pthread_mutex_destroy (pthread_mutex_t *__mutex);
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libc_hidden_proto (__pthread_mutex_destroy)
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extern int __pthread_mutex_trylock (pthread_mutex_t *__mutex);
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extern int __pthread_mutex_lock (pthread_mutex_t *__mutex);
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libc_hidden_proto (__pthread_mutex_lock)
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extern int __pthread_mutex_unlock (pthread_mutex_t *__mutex);
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libc_hidden_proto (__pthread_mutex_unlock)
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extern int __pthread_mutexattr_destroy (pthread_mutexattr_t *__attr);
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extern int __pthread_rwlock_init (pthread_rwlock_t *__rwlock,
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const pthread_rwlockattr_t *__attr);
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libc_hidden_proto (__pthread_rwlock_init)
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extern int __pthread_rwlock_destroy (pthread_rwlock_t *__rwlock);
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extern int __pthread_rwlock_rdlock (pthread_rwlock_t *__rwlock);
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libc_hidden_proto (__pthread_rwlock_rdlock)
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extern int __pthread_rwlock_wrlock (pthread_rwlock_t *__rwlock);
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libc_hidden_proto (__pthread_rwlock_wrlock)
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extern int __pthread_rwlock_unlock (pthread_rwlock_t *__rwlock);
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libc_hidden_proto (__pthread_rwlock_unlock)
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extern int __pthread_once (pthread_once_t *__once_control,
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void (*__init_routine) (void));
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libc_hidden_proto (__pthread_once)
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extern int __pthread_atfork (void (*__prepare) (void),
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void (*__parent) (void),
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void (*__child) (void));
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extern int __pthread_setcancelstate (int state, int *oldstate);
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libc_hidden_proto (__pthread_setcancelstate)
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/* Make the pthread functions weak so that we can elide them from
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single-threaded processes. */
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#ifndef __NO_WEAK_PTHREAD_ALIASES
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# ifdef weak_extern
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weak_extern (__pthread_mutex_trylock)
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weak_extern (__pthread_mutexattr_destroy)
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weak_extern (__pthread_initialize)
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weak_extern (__pthread_atfork)
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# else
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# pragma weak __pthread_mutex_trylock
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# pragma weak __pthread_mutexattr_destroy
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# pragma weak __pthread_initialize
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# pragma weak __pthread_atfork
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# endif
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#endif
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#endif /* libc-lockP.h */
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