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/*-

 * Copyright (c) 2007 Pawel Jakub Dawidek <pjd@FreeBSD.org>

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND

 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE

 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS

 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY

 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

 * SUCH DAMAGE.

 *

 * $FreeBSD$

 */

 

#ifndef _OPENSOLARIS_SYS_RWLOCK_H_

#define _OPENSOLARIS_SYS_RWLOCK_H_

 

#include <sys/param.h>

#include <sys/proc.h>

#include <sys/lock.h>

#include <sys/sx.h>

 

#ifdef _KERNEL

 

typedef enum {

        RW_DEFAULT = 4          /* kernel default rwlock */

} krw_type_t;

 

typedef enum {

        RW_WRITER,

        RW_READER

} krw_t;

 

typedef struct sx       krwlock_t;

 

#ifndef DEBUG

#define RW_FLAGS        (SX_DUPOK | SX_NOWITNESS)

#else

#define RW_FLAGS        (SX_DUPOK)

#endif

 

#define RW_READ_HELD(x)         (rw_read_held((x)))

#define RW_WRITE_HELD(x)        (rw_write_held((x)))

#define RW_LOCK_HELD(x)         (rw_lock_held((x)))

#define RW_ISWRITER(x)          (rw_iswriter(x))

 

#define rw_init(lock, desc, type, arg)  do {                            \

        const char *_name;                                              \

        ASSERT((type) == 0 || (type) == RW_DEFAULT);                    \

        KASSERT(((lock)->lock_object.lo_flags & LO_ALLMASK) !=          \

            LO_EXPECTED, ("lock %s already initialized", #lock));       \

        bzero((lock), sizeof(struct sx));                               \

        for (_name = #lock; *_name != '\0'; _name++) {                  \

                if (*_name >= 'a' && *_name <= 'z')                     \

                        break;                                          \

        }                                                               \

        if (*_name == '\0')                                             \

                _name = #lock;                                          \

        sx_init_flags((lock), _name, RW_FLAGS);                         \

} while (0)

#define rw_destroy(lock)        sx_destroy(lock)

#define rw_enter(lock, how)     do {                                    \

        if ((how) == RW_READER)                                         \

                sx_slock(lock);                                         \

        else /* if ((how) == RW_WRITER) */                              \

                sx_xlock(lock);                                         \

} while (0)

#define rw_tryenter(lock, how)  ((how) == RW_READER ? sx_try_slock(lock) : sx_try_xlock(lock))

#define rw_exit(lock)           sx_unlock(lock)

#define rw_downgrade(lock)      sx_downgrade(lock)

#define rw_tryupgrade(lock)     sx_try_upgrade(lock)

#define rw_read_held(lock)      ((lock)->sx_lock != SX_LOCK_UNLOCKED && ((lock)->sx_lock & SX_LOCK_SHARED))

#define rw_write_held(lock)     sx_xlocked(lock)

#define rw_lock_held(lock)      (rw_read_held(lock) || rw_write_held(lock))

#define rw_iswriter(lock)       sx_xlocked(lock)

/* TODO: Change to sx_xholder() once it is moved from kern_sx.c to sx.h. */

#define rw_owner(lock)          ((lock)->sx_lock & SX_LOCK_SHARED ? NULL : (struct thread *)SX_OWNER((lock)->sx_lock))

 

#endif  /* defined(_KERNEL) */

 

#endif  /* _OPENSOLARIS_SYS_RWLOCK_H_ */