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/* $OpenBSD: lock_machdep.c,v 1.23 2017/04/30 16:45:45 mpi Exp $ */
/* $NetBSD: lock_machdep.c,v 1.1.2.3 2000/05/03 14:40:30 sommerfeld Exp $ */
/*-
* Copyright (c) 1998, 1999 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
* NASA Ames Research Center.
*
* 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/
/*
* Machine-dependent spin lock operations.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/atomic.h>
#include <sys/witness.h>
#include <sys/_lock.h>
#include <machine/lock.h>
#include <machine/cpufunc.h>
#include <ddb/db_output.h>
#ifdef MULTIPROCESSOR
void
___mp_lock_init(struct __mp_lock *mpl)
{
memset(mpl->mpl_cpus, 0, sizeof(mpl->mpl_cpus));
mpl->mpl_users = 0;
mpl->mpl_ticket = 1;
}
#if defined(MP_LOCKDEBUG)
#ifndef DDB
#error "MP_LOCKDEBUG requires DDB"
#endif
/* CPU-dependent timing, needs this to be settable from ddb. */
extern int __mp_lock_spinout;
#endif
static __inline void
__mp_lock_spin(struct __mp_lock *mpl, u_int me)
{
#ifndef MP_LOCKDEBUG
while (mpl->mpl_ticket != me)
SPINLOCK_SPIN_HOOK;
#else
int nticks = __mp_lock_spinout;
while (mpl->mpl_ticket != me) {
SPINLOCK_SPIN_HOOK;
if (--nticks <= 0) {
db_printf("__mp_lock(%p): lock spun out", mpl);
db_enter();
nticks = __mp_lock_spinout;
}
}
#endif
}
void
___mp_lock(struct __mp_lock *mpl LOCK_FL_VARS)
{
struct __mp_lock_cpu *cpu = &mpl->mpl_cpus[cpu_number()];
long ef = read_eflags();
#ifdef WITNESS
int lock_held;
lock_held = __mp_lock_held(mpl);
if (!lock_held)
WITNESS_CHECKORDER(&mpl->mpl_lock_obj,
LOP_EXCLUSIVE | LOP_NEWORDER, file, line, NULL);
#endif
disable_intr();
if (cpu->mplc_depth++ == 0)
cpu->mplc_ticket = atomic_inc_int_nv(&mpl->mpl_users);
write_eflags(ef);
__mp_lock_spin(mpl, cpu->mplc_ticket);
WITNESS_LOCK(&mpl->mpl_lock_obj, LOP_EXCLUSIVE, file, line);
}
void
___mp_unlock(struct __mp_lock *mpl LOCK_FL_VARS)
{
struct __mp_lock_cpu *cpu = &mpl->mpl_cpus[cpu_number()];
int ef = read_eflags();
#ifdef MP_LOCKDEBUG
if (!__mp_lock_held(mpl)) {
db_printf("__mp_unlock(%p): not held lock\n", mpl);
db_enter();
}
#endif
WITNESS_UNLOCK(&mpl->mpl_lock_obj, LOP_EXCLUSIVE, file, line);
disable_intr();
if (--cpu->mplc_depth == 0)
mpl->mpl_ticket++;
write_eflags(ef);
}
int
___mp_release_all(struct __mp_lock *mpl LOCK_FL_VARS)
{
struct __mp_lock_cpu *cpu = &mpl->mpl_cpus[cpu_number()];
int ef = read_eflags();
int rv;
#ifdef WITNESS
int i;
#endif
disable_intr();
rv = cpu->mplc_depth;
#ifdef WITNESS
for (i = 0; i < rv; i++)
WITNESS_UNLOCK(&mpl->mpl_lock_obj, LOP_EXCLUSIVE, file, line);
#endif
cpu->mplc_depth = 0;
mpl->mpl_ticket++;
write_eflags(ef);
return (rv);
}
int
___mp_release_all_but_one(struct __mp_lock *mpl LOCK_FL_VARS)
{
struct __mp_lock_cpu *cpu = &mpl->mpl_cpus[cpu_number()];
int rv = cpu->mplc_depth - 1;
#ifdef WITNESS
int i;
for (i = 0; i < rv; i++)
WITNESS_UNLOCK(&mpl->mpl_lock_obj, LOP_EXCLUSIVE, file, line);
#endif
cpu->mplc_depth = 1;
return (rv);
}
void
___mp_acquire_count(struct __mp_lock *mpl, int count LOCK_FL_VARS)
{
while (count--)
___mp_lock(mpl LOCK_FL_ARGS);
}
int
__mp_lock_held(struct __mp_lock *mpl)
{
struct __mp_lock_cpu *cpu = &mpl->mpl_cpus[cpu_number()];
return (cpu->mplc_ticket == mpl->mpl_ticket && cpu->mplc_depth > 0);
}
#endif
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