mutex_impl.h revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright (c) 1991-1998 by Sun Microsystems, Inc.
* All rights reserved.
*/
#ifndef _SYS_MUTEX_IMPL_H
#define _SYS_MUTEX_IMPL_H
#pragma ident "%Z%%M% %I% %E% SMI"
#ifndef _ASM
#include <sys/types.h>
#include <sys/machlock.h>
#endif
#ifdef __cplusplus
extern "C" {
#endif
#ifndef _ASM
/*
* mutex_enter() assumes that the mutex is adaptive and tries to grab the
* lock by doing an ldstub on byte 0 of the mutex. If the ldstub fails,
* it means that either (1) the lock is a spin lock, or (2) the lock is
* adaptive but already held. mutex_vector_enter() distinguishes these
* cases by looking at the mutex type, which is byte 7 for both types.
*
* Once the lock byte is set for an adaptive lock, the owner is stuffed
* into the remaining 24 bits such that the owner word is 0xff:owner24.
* This works because a thread pointer only has 24 significant bits: the
* upper 3 bits are 111 (since all kernel addresses are above 0xe0000000),
* and the lower 5 bits are zero (because threads are 32-byte aligned).
*/
typedef union mutex_impl {
/*
* Adaptive mutex.
*/
struct adaptive_mutex {
uintptr_t _m_owner; /* 0-3 owner and lock */
uchar_t _m_waiters; /* 4 are there waiters? */
uchar_t _m_filler[2]; /* 5-6 unused */
uchar_t _m_type; /* 7 type */
} m_adaptive;
/*
* Spin Mutex.
*/
struct spin_mutex {
lock_t m_dummylock; /* 0 lock (always set) */
lock_t m_spinlock; /* 1 real lock */
ushort_t m_oldspl; /* 2-3 old %psr value */
ushort_t m_minspl; /* 4-5 min PSR_PIL val if lock held */
uchar_t m_filler; /* 6 unused */
uchar_t _m_type; /* 7 type */
} m_spin;
} mutex_impl_t;
#define m_owner m_adaptive._m_owner
#define m_waiters m_adaptive._m_waiters
#define m_type m_adaptive._m_type
/*
* Macro to retrieve 32-bit pointer field out of mutex.
* Relies on 32-byte alignment of thread structures.
* Also relies on KERNELBASE (and all thread pointers)
* being above 0xe0000000.
*/
#define MUTEX_OWNER(lp) ((kthread_id_t)((lp)->m_owner << PTR24_LSB))
#define MUTEX_NO_OWNER ((kthread_id_t)PTR24_BASE)
#define MUTEX_SET_WAITERS(lp) ((lp)->m_waiters = 1)
#define MUTEX_HAS_WAITERS(lp) ((lp)->m_waiters != 0)
#define MUTEX_CLEAR_LOCK_AND_WAITERS(lp) \
(lp)->m_waiters = 0, (lp)->m_owner = 0
#define MUTEX_SET_TYPE(lp, type) (lp)->m_type = (type)
#define MUTEX_TYPE_ADAPTIVE(lp) ((lp)->m_type == MUTEX_ADAPTIVE)
#define MUTEX_TYPE_SPIN(lp) ((lp)->m_type == MUTEX_SPIN)
#define MUTEX_DESTROY(lp) \
(lp)->m_type = 0xdd, LOCK_INIT_HELD(&lp->m_spin.m_dummylock)
#endif /* _ASM */
#ifdef __cplusplus
}
#endif
#endif /* _SYS_MUTEX_IMPL_H */