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/* $OpenBSD: kern_lock.c,v 1.43 2014/01/21 01:48:44 tedu Exp $ */
/*
* Copyright (c) 1995
* The Regents of the University of California. All rights reserved.
*
* This code contains ideas from software contributed to Berkeley by
* Avadis Tevanian, Jr., Michael Wayne Young, and the Mach Operating
* System project at Carnegie-Mellon University.
*
* 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.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
*
* @(#)kern_lock.c 8.18 (Berkeley) 5/21/95
*/
#include <sys/param.h>
#include <sys/proc.h>
#include <sys/lock.h>
#include <sys/systm.h>
#include <sys/sched.h>
#ifdef MP_LOCKDEBUG
/* CPU-dependent timing, this needs to be settable from ddb. */
int __mp_lock_spinout = 200000000;
#endif
/*
* Initialize a lock; required before use.
*/
void
lockinit(struct lock *lkp, int prio, char *wmesg, int timo, int flags)
{
KASSERT(flags == 0);
memset(lkp, 0, sizeof(struct lock));
rrw_init(&lkp->lk_lck, wmesg);
}
int
lockstatus(struct lock *lkp)
{
switch (rrw_status(&lkp->lk_lck)) {
case RW_WRITE:
return (LK_EXCLUSIVE);
case RW_READ:
return (LK_SHARED);
case 0:
default:
return (0);
}
}
int
lockmgr(struct lock *lkp, u_int flags, void *notused)
{
int rwflags = 0;
KASSERT(!((flags & (LK_SHARED|LK_EXCLUSIVE)) ==
(LK_SHARED|LK_EXCLUSIVE)));
KASSERT(!((flags & (LK_CANRECURSE|LK_RECURSEFAIL)) ==
(LK_CANRECURSE|LK_RECURSEFAIL)));
KASSERT((flags & LK_RELEASE) ||
(flags & (LK_SHARED|LK_EXCLUSIVE|LK_DRAIN)));
if (flags & LK_RELEASE) {
rrw_exit(&lkp->lk_lck);
return (0);
}
if (flags & LK_SHARED)
rwflags |= RW_READ;
if (flags & (LK_EXCLUSIVE|LK_DRAIN))
rwflags |= RW_WRITE;
if (flags & LK_RECURSEFAIL)
rwflags |= RW_RECURSEFAIL;
if (flags & LK_NOWAIT)
rwflags |= RW_NOSLEEP;
return (rrw_enter(&lkp->lk_lck, rwflags));
}
#if defined(MULTIPROCESSOR)
/*
* Functions for manipulating the kernel_lock. We put them here
* so that they show up in profiles.
*/
struct __mp_lock kernel_lock;
void
_kernel_lock_init(void)
{
__mp_lock_init(&kernel_lock);
}
/*
* Acquire/release the kernel lock. Intended for use in the scheduler
* and the lower half of the kernel.
*/
void
_kernel_lock(void)
{
SCHED_ASSERT_UNLOCKED();
__mp_lock(&kernel_lock);
}
void
_kernel_unlock(void)
{
__mp_unlock(&kernel_lock);
}
#endif /* MULTIPROCESSOR */
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