Current File : //usr/include/bits/thread-shared-types.h
/* Common threading primitives definitions for both POSIX and C11.
Copyright (C) 2017-2018 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_SHARED_TYPES_H
#define _THREAD_SHARED_TYPES_H 1
/* Arch-specific definitions. Each architecture must define the following
macros to define the expected sizes of pthread data types:
__SIZEOF_PTHREAD_ATTR_T - size of pthread_attr_t.
__SIZEOF_PTHREAD_MUTEX_T - size of pthread_mutex_t.
__SIZEOF_PTHREAD_MUTEXATTR_T - size of pthread_mutexattr_t.
__SIZEOF_PTHREAD_COND_T - size of pthread_cond_t.
__SIZEOF_PTHREAD_CONDATTR_T - size of pthread_condattr_t.
__SIZEOF_PTHREAD_RWLOCK_T - size of pthread_rwlock_t.
__SIZEOF_PTHREAD_RWLOCKATTR_T - size of pthread_rwlockattr_t.
__SIZEOF_PTHREAD_BARRIER_T - size of pthread_barrier_t.
__SIZEOF_PTHREAD_BARRIERATTR_T - size of pthread_barrierattr_t.
Also, the following macros must be define for internal pthread_mutex_t
struct definitions (struct __pthread_mutex_s):
__PTHREAD_COMPAT_PADDING_MID - any additional members after 'kind'
and before '__spin' (for 64 bits) or
'__nusers' (for 32 bits).
__PTHREAD_COMPAT_PADDING_END - any additional members at the end of
the internal structure.
__PTHREAD_MUTEX_LOCK_ELISION - 1 if the architecture supports lock
elision or 0 otherwise.
__PTHREAD_MUTEX_NUSERS_AFTER_KIND - control where to put __nusers. The
preferred value for new architectures
is 0.
__PTHREAD_MUTEX_USE_UNION - control whether internal __spins and
__list will be place inside a union for
linuxthreads compatibility.
The preferred value for new architectures
is 0.
For a new port the preferred values for the required defines are:
#define __PTHREAD_COMPAT_PADDING_MID
#define __PTHREAD_COMPAT_PADDING_END
#define __PTHREAD_MUTEX_LOCK_ELISION 0
#define __PTHREAD_MUTEX_NUSERS_AFTER_KIND 0
#define __PTHREAD_MUTEX_USE_UNION 0
__PTHREAD_MUTEX_LOCK_ELISION can be set to 1 if the hardware plans to
eventually support lock elision using transactional memory.
The additional macro defines any constraint for the lock alignment
inside the thread structures:
__LOCK_ALIGNMENT - for internal lock/futex usage.
Same idea but for the once locking primitive:
__ONCE_ALIGNMENT - for pthread_once_t/once_flag definition.
And finally the internal pthread_rwlock_t (struct __pthread_rwlock_arch_t)
must be defined.
*/
#include <bits/pthreadtypes-arch.h>
/* Common definition of pthread_mutex_t. */
#if !__PTHREAD_MUTEX_USE_UNION
typedef struct __pthread_internal_list
{
struct __pthread_internal_list *__prev;
struct __pthread_internal_list *__next;
} __pthread_list_t;
#else
typedef struct __pthread_internal_slist
{
struct __pthread_internal_slist *__next;
} __pthread_slist_t;
#endif
/* Lock elision support. */
#if __PTHREAD_MUTEX_LOCK_ELISION
# if !__PTHREAD_MUTEX_USE_UNION
# define __PTHREAD_SPINS_DATA \
short __spins; \
short __elision
# define __PTHREAD_SPINS 0, 0
# else
# define __PTHREAD_SPINS_DATA \
struct \
{ \
short __espins; \
short __eelision; \
} __elision_data
# define __PTHREAD_SPINS { 0, 0 }
# define __spins __elision_data.__espins
# define __elision __elision_data.__eelision
# endif
#else
# define __PTHREAD_SPINS_DATA int __spins
/* Mutex __spins initializer used by PTHREAD_MUTEX_INITIALIZER. */
# define __PTHREAD_SPINS 0
#endif
struct __pthread_mutex_s
{
int __lock __LOCK_ALIGNMENT;
unsigned int __count;
int __owner;
#if !__PTHREAD_MUTEX_NUSERS_AFTER_KIND
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 or elision can
be enabled. This is done concurrently in the pthread_mutex_*lock functions
by using the macro FORCE_ELISION. This macro is only defined for
architectures which supports lock elision.
For elision, there are the flags PTHREAD_MUTEX_ELISION_NP and
PTHREAD_MUTEX_NO_ELISION_NP which can be set in addition to the already set
type of a mutex.
Before a mutex is initialized, only PTHREAD_MUTEX_NO_ELISION_NP can be set
with pthread_mutexattr_settype.
After a mutex has been initialized, the functions pthread_mutex_*lock can
enable elision - if the mutex-type and the machine supports it - by setting
the flag PTHREAD_MUTEX_ELISION_NP. This is done concurrently. Afterwards
the lock / unlock functions are using specific elision code-paths. */
int __kind;
__PTHREAD_COMPAT_PADDING_MID
#if __PTHREAD_MUTEX_NUSERS_AFTER_KIND
unsigned int __nusers;
#endif
#if !__PTHREAD_MUTEX_USE_UNION
__PTHREAD_SPINS_DATA;
__pthread_list_t __list;
# define __PTHREAD_MUTEX_HAVE_PREV 1
#else
__extension__ union
{
__PTHREAD_SPINS_DATA;
__pthread_slist_t __list;
};
# define __PTHREAD_MUTEX_HAVE_PREV 0
#endif
__PTHREAD_COMPAT_PADDING_END
};
/* Common definition of pthread_cond_t. */
struct __pthread_cond_s
{
__extension__ union
{
__extension__ unsigned long long int __wseq;
struct
{
unsigned int __low;
unsigned int __high;
} __wseq32;
};
__extension__ union
{
__extension__ unsigned long long int __g1_start;
struct
{
unsigned int __low;
unsigned int __high;
} __g1_start32;
};
unsigned int __g_refs[2] __LOCK_ALIGNMENT;
unsigned int __g_size[2];
unsigned int __g1_orig_size;
unsigned int __wrefs;
unsigned int __g_signals[2];
};
#endif /* _THREAD_SHARED_TYPES_H */
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