/*
* Copyright (c) 2021 Apple Inc. All rights reserved.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
*
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
* Version 2.0 (the 'License'). You may not use this file except in
* compliance with the License. The rights granted to you under the License
* may not be used to create, or enable the creation or redistribution of,
* unlawful or unlicensed copies of an Apple operating system, or to
* circumvent, violate, or enable the circumvention or violation of, any
* terms of an Apple operating system software license agreement.
*
* Please obtain a copy of the License at
* http://www.opensource.apple.com/apsl/ and read it before using this file.
*
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
* Please see the License for the specific language governing rights and
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*/
#ifndef _KERN_LOCK_ATTR_H_
#define _KERN_LOCK_ATTR_H_
#include <kern/lock_types.h>
__BEGIN_DECLS
#ifdef XNU_KERNEL_PRIVATE
typedef struct _lck_attr_ {
unsigned int lck_attr_val;
} lck_attr_t;
extern lck_attr_t lck_attr_default;
#define LCK_ATTR_NONE 0
#define LCK_ATTR_DEBUG 0x00000001
#define LCK_ATTR_RW_SHARED_PRIORITY 0x00010000
#else /* !XNU_KERNEL_PRIVATE */
typedef struct __lck_attr__ lck_attr_t;
#endif /* !XNU_KERNEL_PRIVATE */
#define LCK_ATTR_NULL ((lck_attr_t *)NULL)
extern lck_attr_t *lck_attr_alloc_init(void);
extern void lck_attr_setdefault(
lck_attr_t *attr);
extern void lck_attr_setdebug(
lck_attr_t *attr);
extern void lck_attr_cleardebug(
lck_attr_t *attr);
extern void lck_attr_free(
lck_attr_t *attr);
#ifdef XNU_KERNEL_PRIVATE
/*!
* @function lck_attr_rw_shared_priority
*
* @abstract
* Changes the rw lock behaviour by setting reader priority over writer.
*
* @discussion
* The attribute needs to be set before calling lck_rw_init().
* This attribute changes the locking behaviour by possibly starving the writers.
* Readers will always be able to lock the lock as long as a writer is not holding it.
* This attribute was added to allow recursive locking in shared mode.
*
* @param attr attr to modify
*/
extern void lck_attr_rw_shared_priority(
lck_attr_t *attr);
#endif /* XNU_KERNEL_PRIVATE */
__END_DECLS
#endif /* _KERN_LOCK_ATTR_H_ */