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NetBSD/sys/kern/kern_lock.c

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/* $NetBSD: kern_lock.c,v 1.26 2000/02/09 16:46:09 sommerfeld Exp $ */
/*-
* Copyright (c) 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.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Ross Harvey.
*
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the NetBSD
* Foundation, Inc. and its contributors.
* 4. Neither the name of The NetBSD Foundation 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 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.
*/
/*
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. 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 "opt_multiprocessor.h"
#include "opt_lockdebug.h"
#include "opt_ddb.h"
#include <sys/param.h>
#include <sys/proc.h>
#include <sys/lock.h>
#include <sys/systm.h>
#include <machine/cpu.h>
#if defined(LOCKDEBUG)
#include <sys/syslog.h>
/*
* note that stdarg.h and the ansi style va_start macro is used for both
* ansi and traditional c compiles.
* XXX: this requires that stdarg.h define: va_alist and va_dcl
*/
#include <machine/stdarg.h>
void lock_printf __P((const char *fmt, ...));
int lock_debug_syslog = 0; /* defaults to printf, but can be patched */
#endif
/*
* Locking primitives implementation.
* Locks provide shared/exclusive sychronization.
*/
#if defined(LOCKDEBUG) || defined(DIAGNOSTIC) /* { */
#if defined(MULTIPROCESSOR) /* { */
#define COUNT_CPU(cpu_id, x) \
/* atomic_add_ulong(&curcpu().ci_spin_locks, (x)) */
#else
u_long spin_locks;
#define COUNT_CPU(cpu_id, x) spin_locks += (x)
#endif /* MULTIPROCESSOR */ /* } */
#define COUNT(lkp, p, cpu_id, x) \
do { \
if ((lkp)->lk_flags & LK_SPIN) \
COUNT_CPU((cpu_id), (x)); \
else \
(p)->p_locks += (x); \
} while (0)
#else
#define COUNT(lkp, p, cpu_id, x)
#endif /* LOCKDEBUG || DIAGNOSTIC */ /* } */
/*
* Acquire a resource.
*/
#define ACQUIRE(lkp, error, extflags, drain, wanted) \
if ((extflags) & LK_SPIN) { \
int interlocked; \
\
if ((drain) == 0) \
(lkp)->lk_waitcount++; \
for (interlocked = 1;;) { \
if (wanted) { \
if (interlocked) { \
simple_unlock(&(lkp)->lk_interlock); \
interlocked = 0; \
} \
} else if (interlocked) { \
break; \
} else { \
simple_lock(&(lkp)->lk_interlock); \
interlocked = 1; \
} \
} \
if ((drain) == 0) \
(lkp)->lk_waitcount--; \
KASSERT((wanted) == 0); \
error = 0; /* sanity */ \
} else { \
for (error = 0; wanted; ) { \
if ((drain)) \
(lkp)->lk_flags |= LK_WAITDRAIN; \
else \
(lkp)->lk_waitcount++; \
simple_unlock(&(lkp)->lk_interlock); \
/* XXX Cast away volatile. */ \
error = tsleep((drain) ? &(lkp)->lk_flags : \
(void *)(lkp), (lkp)->lk_prio, \
(lkp)->lk_wmesg, (lkp)->lk_timo); \
simple_lock(&(lkp)->lk_interlock); \
if ((drain) == 0) \
(lkp)->lk_waitcount--; \
if (error) \
break; \
if ((extflags) & LK_SLEEPFAIL) { \
error = ENOLCK; \
break; \
} \
} \
}
#define SETHOLDER(lkp, pid, cpu_id) \
do { \
if ((lkp)->lk_flags & LK_SPIN) \
(lkp)->lk_cpu = cpu_id; \
else \
(lkp)->lk_lockholder = pid; \
} while (0)
#define WEHOLDIT(lkp, pid, cpu_id) \
(((lkp)->lk_flags & LK_SPIN) != 0 ? \
((lkp)->lk_cpu == (cpu_id)) : ((lkp)->lk_lockholder == (pid)))
#define WAKEUP_WAITER(lkp) \
do { \
if (((lkp)->lk_flags & LK_SPIN) == 0 && (lkp)->lk_waitcount) { \
/* XXX Cast away volatile. */ \
wakeup_one((void *)(lkp)); \
} \
} while (0)
#if defined(LOCKDEBUG) /* { */
#if defined(MULTIPROCESSOR) /* { */
struct simplelock spinlock_list_slock = SIMPLELOCK_INITIALIZER;
#define SPINLOCK_LIST_LOCK() cpu_simple_lock(&spinlock_list_slock)
#define SPINLOCK_LIST_UNLOCK() cpu_simple_unlock(&spinlock_list_slock)
#else
#define SPINLOCK_LIST_LOCK() /* nothing */
#define SPINLOCK_LIST_UNLOCK() /* nothing */
#endif /* MULTIPROCESSOR */ /* } */
TAILQ_HEAD(, lock) spinlock_list =
TAILQ_HEAD_INITIALIZER(spinlock_list);
#define HAVEIT(lkp) \
do { \
if ((lkp)->lk_flags & LK_SPIN) { \
int s = splhigh(); \
SPINLOCK_LIST_LOCK(); \
/* XXX Cast away volatile. */ \
TAILQ_INSERT_TAIL(&spinlock_list, (struct lock *)(lkp), \
lk_list); \
SPINLOCK_LIST_UNLOCK(); \
splx(s); \
} \
} while (0)
#define DONTHAVEIT(lkp) \
do { \
if ((lkp)->lk_flags & LK_SPIN) { \
int s = splhigh(); \
SPINLOCK_LIST_LOCK(); \
/* XXX Cast away volatile. */ \
TAILQ_REMOVE(&spinlock_list, (struct lock *)(lkp), \
lk_list); \
SPINLOCK_LIST_UNLOCK(); \
splx(s); \
} \
} while (0)
#else
#define HAVEIT(lkp) /* nothing */
#define DONTHAVEIT(lkp) /* nothing */
#endif /* LOCKDEBUG */ /* } */
#if defined(LOCKDEBUG)
/*
* Lock debug printing routine; can be configured to print to console
* or log to syslog.
*/
void
#ifdef __STDC__
lock_printf(const char *fmt, ...)
#else
lock_printf(fmt, va_alist)
char *fmt;
va_dcl
#endif
{
va_list ap;
va_start(ap, fmt);
if (lock_debug_syslog)
vlog(LOG_DEBUG, fmt, ap);
else
vprintf(fmt, ap);
va_end(ap);
}
#endif /* LOCKDEBUG */
/*
* Initialize a lock; required before use.
*/
void
lockinit(lkp, prio, wmesg, timo, flags)
struct lock *lkp;
int prio;
const char *wmesg;
int timo;
int flags;
{
memset(lkp, 0, sizeof(struct lock));
simple_lock_init(&lkp->lk_interlock);
lkp->lk_flags = flags & LK_EXTFLG_MASK;
if (flags & LK_SPIN)
lkp->lk_cpu = LK_NOCPU;
else {
lkp->lk_lockholder = LK_NOPROC;
lkp->lk_prio = prio;
lkp->lk_timo = timo;
}
lkp->lk_wmesg = wmesg; /* just a name for spin locks */
}
/*
* Determine the status of a lock.
*/
int
lockstatus(lkp)
struct lock *lkp;
{
int lock_type = 0;
simple_lock(&lkp->lk_interlock);
if (lkp->lk_exclusivecount != 0)
lock_type = LK_EXCLUSIVE;
else if (lkp->lk_sharecount != 0)
lock_type = LK_SHARED;
simple_unlock(&lkp->lk_interlock);
return (lock_type);
}
/*
* Set, change, or release a lock.
*
* Shared requests increment the shared count. Exclusive requests set the
* LK_WANT_EXCL flag (preventing further shared locks), and wait for already
* accepted shared locks and shared-to-exclusive upgrades to go away.
*/
int
lockmgr(lkp, flags, interlkp)
__volatile struct lock *lkp;
u_int flags;
struct simplelock *interlkp;
{
int error;
pid_t pid;
int extflags;
cpuid_t cpu_id;
struct proc *p = curproc;
error = 0;
simple_lock(&lkp->lk_interlock);
if (flags & LK_INTERLOCK)
simple_unlock(interlkp);
extflags = (flags | lkp->lk_flags) & LK_EXTFLG_MASK;
#ifdef DIAGNOSTIC /* { */
/*
* Don't allow spins on sleep locks and don't allow sleeps
* on spin locks.
*/
if ((flags ^ lkp->lk_flags) & LK_SPIN)
panic("lockmgr: sleep/spin mismatch\n");
#endif /* } */
if (extflags & LK_SPIN)
pid = LK_KERNPROC;
else {
#ifdef DIAGNOSTIC /* { */
if (p == NULL)
panic("lockmgr: no context");
#endif /* } */
pid = p->p_pid;
}
cpu_id = cpu_number();
#ifdef DIAGNOSTIC /* { */
/*
* Once a lock has drained, the LK_DRAINING flag is set and an
* exclusive lock is returned. The only valid operation thereafter
* is a single release of that exclusive lock. This final release
* clears the LK_DRAINING flag and sets the LK_DRAINED flag. Any
* further requests of any sort will result in a panic. The bits
* selected for these two flags are chosen so that they will be set
* in memory that is freed (freed memory is filled with 0xdeadbeef).
* The final release is permitted to give a new lease on life to
* the lock by specifying LK_REENABLE.
*/
if (lkp->lk_flags & (LK_DRAINING|LK_DRAINED)) {
if (lkp->lk_flags & LK_DRAINED)
panic("lockmgr: using decommissioned lock");
if ((flags & LK_TYPE_MASK) != LK_RELEASE ||
WEHOLDIT(lkp, pid, cpu_id) == 0)
panic("lockmgr: non-release on draining lock: %d\n",
flags & LK_TYPE_MASK);
lkp->lk_flags &= ~LK_DRAINING;
if ((flags & LK_REENABLE) == 0)
lkp->lk_flags |= LK_DRAINED;
}
#endif /* DIAGNOSTIC */ /* } */
switch (flags & LK_TYPE_MASK) {
case LK_SHARED:
if (WEHOLDIT(lkp, pid, cpu_id) == 0) {
/*
* If just polling, check to see if we will block.
*/
if ((extflags & LK_NOWAIT) && (lkp->lk_flags &
(LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE))) {
error = EBUSY;
break;
}
/*
* Wait for exclusive locks and upgrades to clear.
*/
ACQUIRE(lkp, error, extflags, 0, lkp->lk_flags &
(LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE));
if (error)
break;
lkp->lk_sharecount++;
COUNT(lkp, p, cpu_id, 1);
break;
}
/*
* We hold an exclusive lock, so downgrade it to shared.
* An alternative would be to fail with EDEADLK.
*/
lkp->lk_sharecount++;
COUNT(lkp, p, cpu_id, 1);
/* fall into downgrade */
case LK_DOWNGRADE:
if (WEHOLDIT(lkp, pid, cpu_id) == 0 ||
lkp->lk_exclusivecount == 0)
panic("lockmgr: not holding exclusive lock");
lkp->lk_sharecount += lkp->lk_exclusivecount;
lkp->lk_exclusivecount = 0;
lkp->lk_recurselevel = 0;
lkp->lk_flags &= ~LK_HAVE_EXCL;
SETHOLDER(lkp, LK_NOPROC, LK_NOCPU);
DONTHAVEIT(lkp);
WAKEUP_WAITER(lkp);
break;
case LK_EXCLUPGRADE:
/*
* If another process is ahead of us to get an upgrade,
* then we want to fail rather than have an intervening
* exclusive access.
*/
if (lkp->lk_flags & LK_WANT_UPGRADE) {
lkp->lk_sharecount--;
COUNT(lkp, p, cpu_id, -1);
error = EBUSY;
break;
}
/* fall into normal upgrade */
case LK_UPGRADE:
/*
* Upgrade a shared lock to an exclusive one. If another
* shared lock has already requested an upgrade to an
* exclusive lock, our shared lock is released and an
* exclusive lock is requested (which will be granted
* after the upgrade). If we return an error, the file
* will always be unlocked.
*/
if (WEHOLDIT(lkp, pid, cpu_id) || lkp->lk_sharecount <= 0)
panic("lockmgr: upgrade exclusive lock");
lkp->lk_sharecount--;
COUNT(lkp, p, cpu_id, -1);
/*
* If we are just polling, check to see if we will block.
*/
if ((extflags & LK_NOWAIT) &&
((lkp->lk_flags & LK_WANT_UPGRADE) ||
lkp->lk_sharecount > 1)) {
error = EBUSY;
break;
}
if ((lkp->lk_flags & LK_WANT_UPGRADE) == 0) {
/*
* We are first shared lock to request an upgrade, so
* request upgrade and wait for the shared count to
* drop to zero, then take exclusive lock.
*/
lkp->lk_flags |= LK_WANT_UPGRADE;
ACQUIRE(lkp, error, extflags, 0, lkp->lk_sharecount);
lkp->lk_flags &= ~LK_WANT_UPGRADE;
if (error)
break;
lkp->lk_flags |= LK_HAVE_EXCL;
SETHOLDER(lkp, pid, cpu_id);
HAVEIT(lkp);
if (lkp->lk_exclusivecount != 0)
panic("lockmgr: non-zero exclusive count");
lkp->lk_exclusivecount = 1;
if (extflags & LK_SETRECURSE)
lkp->lk_recurselevel = 1;
COUNT(lkp, p, cpu_id, 1);
break;
}
/*
* Someone else has requested upgrade. Release our shared
* lock, awaken upgrade requestor if we are the last shared
* lock, then request an exclusive lock.
*/
if (lkp->lk_sharecount == 0)
WAKEUP_WAITER(lkp);
/* fall into exclusive request */
case LK_EXCLUSIVE:
if (WEHOLDIT(lkp, pid, cpu_id)) {
/*
* Recursive lock.
*/
if ((extflags & LK_CANRECURSE) == 0 &&
lkp->lk_recurselevel == 0) {
if (extflags & LK_RECURSEFAIL) {
error = EDEADLK;
break;
} else
panic("lockmgr: locking against myself");
}
lkp->lk_exclusivecount++;
if (extflags & LK_SETRECURSE &&
lkp->lk_recurselevel == 0)
lkp->lk_recurselevel = lkp->lk_exclusivecount;
COUNT(lkp, p, cpu_id, 1);
break;
}
/*
* If we are just polling, check to see if we will sleep.
*/
if ((extflags & LK_NOWAIT) && ((lkp->lk_flags &
(LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE)) ||
lkp->lk_sharecount != 0)) {
error = EBUSY;
break;
}
/*
* Try to acquire the want_exclusive flag.
*/
ACQUIRE(lkp, error, extflags, 0, lkp->lk_flags &
(LK_HAVE_EXCL | LK_WANT_EXCL));
if (error)
break;
lkp->lk_flags |= LK_WANT_EXCL;
/*
* Wait for shared locks and upgrades to finish.
*/
ACQUIRE(lkp, error, extflags, 0, lkp->lk_sharecount != 0 ||
(lkp->lk_flags & LK_WANT_UPGRADE));
lkp->lk_flags &= ~LK_WANT_EXCL;
if (error)
break;
lkp->lk_flags |= LK_HAVE_EXCL;
SETHOLDER(lkp, pid, cpu_id);
HAVEIT(lkp);
if (lkp->lk_exclusivecount != 0)
panic("lockmgr: non-zero exclusive count");
lkp->lk_exclusivecount = 1;
if (extflags & LK_SETRECURSE)
lkp->lk_recurselevel = 1;
COUNT(lkp, p, cpu_id, 1);
break;
case LK_RELEASE:
if (lkp->lk_exclusivecount != 0) {
if (WEHOLDIT(lkp, pid, cpu_id) == 0) {
if (lkp->lk_flags & LK_SPIN) {
panic("lockmgr: processor %lu, not "
"exclusive lock holder %lu "
"unlocking", cpu_id, lkp->lk_cpu);
} else {
panic("lockmgr: pid %d, not "
"exclusive lock holder %d "
"unlocking", pid,
lkp->lk_lockholder);
}
}
if (lkp->lk_exclusivecount == lkp->lk_recurselevel)
lkp->lk_recurselevel = 0;
lkp->lk_exclusivecount--;
COUNT(lkp, p, cpu_id, -1);
if (lkp->lk_exclusivecount == 0) {
lkp->lk_flags &= ~LK_HAVE_EXCL;
SETHOLDER(lkp, LK_NOPROC, LK_NOCPU);
DONTHAVEIT(lkp);
}
} else if (lkp->lk_sharecount != 0) {
lkp->lk_sharecount--;
COUNT(lkp, p, cpu_id, -1);
}
WAKEUP_WAITER(lkp);
break;
case LK_DRAIN:
/*
* Check that we do not already hold the lock, as it can
* never drain if we do. Unfortunately, we have no way to
* check for holding a shared lock, but at least we can
* check for an exclusive one.
*/
if (WEHOLDIT(lkp, pid, cpu_id))
panic("lockmgr: draining against myself");
/*
* If we are just polling, check to see if we will sleep.
*/
if ((extflags & LK_NOWAIT) && ((lkp->lk_flags &
(LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE)) ||
lkp->lk_sharecount != 0 || lkp->lk_waitcount != 0)) {
error = EBUSY;
break;
}
ACQUIRE(lkp, error, extflags, 1,
((lkp->lk_flags &
(LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE)) ||
lkp->lk_sharecount != 0 ||
lkp->lk_waitcount != 0));
if (error)
break;
lkp->lk_flags |= LK_DRAINING | LK_HAVE_EXCL;
SETHOLDER(lkp, pid, cpu_id);
HAVEIT(lkp);
lkp->lk_exclusivecount = 1;
/* XXX unlikely that we'd want this */
if (extflags & LK_SETRECURSE)
lkp->lk_recurselevel = 1;
COUNT(lkp, p, cpu_id, 1);
break;
default:
simple_unlock(&lkp->lk_interlock);
panic("lockmgr: unknown locktype request %d",
flags & LK_TYPE_MASK);
/* NOTREACHED */
}
if ((lkp->lk_flags & (LK_WAITDRAIN|LK_SPIN)) == LK_WAITDRAIN &&
((lkp->lk_flags &
(LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE)) == 0 &&
lkp->lk_sharecount == 0 && lkp->lk_waitcount == 0)) {
lkp->lk_flags &= ~LK_WAITDRAIN;
wakeup_one((void *)&lkp->lk_flags);
}
simple_unlock(&lkp->lk_interlock);
return (error);
}
/*
* Print out information about state of a lock. Used by VOP_PRINT
* routines to display ststus about contained locks.
*/
void
lockmgr_printinfo(lkp)
__volatile struct lock *lkp;
{
if (lkp->lk_sharecount)
printf(" lock type %s: SHARED (count %d)", lkp->lk_wmesg,
lkp->lk_sharecount);
else if (lkp->lk_flags & LK_HAVE_EXCL) {
printf(" lock type %s: EXCL (count %d) by ",
lkp->lk_wmesg, lkp->lk_exclusivecount);
if (lkp->lk_flags & LK_SPIN)
printf("processor %lu", lkp->lk_cpu);
else
printf("pid %d", lkp->lk_lockholder);
} else
printf(" not locked");
if ((lkp->lk_flags & LK_SPIN) == 0 && lkp->lk_waitcount > 0)
printf(" with %d pending", lkp->lk_waitcount);
}
#if defined(LOCKDEBUG) /* { */
TAILQ_HEAD(, simplelock) simplelock_list =
TAILQ_HEAD_INITIALIZER(simplelock_list);
#if defined(MULTIPROCESSOR) /* { */
struct simplelock simplelock_list_slock = SIMPLELOCK_INITIALIZER;
#define SLOCK_LIST_LOCK() \
cpu_simple_lock(&simplelock_list_slock)
#define SLOCK_LIST_UNLOCK() \
cpu_simple_unlock(&simplelock_list_slock)
#define SLOCK_COUNT(x) \
/* atomic_add_ulong(&curcpu()->ci_simple_locks, (x)) */
#else
u_long simple_locks;
#define SLOCK_LIST_LOCK() /* nothing */
#define SLOCK_LIST_UNLOCK() /* nothing */
#define SLOCK_COUNT(x) simple_locks += (x)
#endif /* MULTIPROCESSOR */ /* } */
#ifdef DDB /* { */
int simple_lock_debugger = 0;
#define SLOCK_DEBUGGER() if (simple_lock_debugger) Debugger()
#else
#define SLOCK_DEBUGGER() /* nothing */
#endif /* } */
#ifdef MULTIPROCESSOR
#define SLOCK_MP() lock_printf("on cpu %d\n", cpu_number())
#else
#define SLOCK_MP() /* nothing */
#endif
#define SLOCK_WHERE(str, alp, id, l) \
do { \
lock_printf(str); \
lock_printf("lock: %p, currently at: %s:%d\n", (alp), (id), (l)); \
SLOCK_MP(); \
if ((alp)->lock_file != NULL) \
lock_printf("last locked: %s:%d\n", (alp)->lock_file, \
(alp)->lock_line); \
if ((alp)->unlock_file != NULL) \
lock_printf("last unlocked: %s:%d\n", (alp)->unlock_file, \
(alp)->unlock_line); \
SLOCK_DEBUGGER(); \
} while (0)
/*
* Simple lock functions so that the debugger can see from whence
* they are being called.
*/
void
simple_lock_init(alp)
struct simplelock *alp;
{
#if defined(MULTIPROCESSOR) /* { */
cpu_simple_lock_init(alp);
#else
alp->lock_data = SIMPLELOCK_UNLOCKED;
#endif /* } */
alp->lock_file = NULL;
alp->lock_line = 0;
alp->unlock_file = NULL;
alp->unlock_line = 0;
alp->lock_holder = 0;
}
void
_simple_lock(alp, id, l)
__volatile struct simplelock *alp;
const char *id;
int l;
{
cpuid_t cpu_id = cpu_number();
int s;
s = splhigh();
/*
* MULTIPROCESSOR case: This is `safe' since if it's not us, we
* don't take any action, and just fall into the normal spin case.
*/
if (alp->lock_data == SIMPLELOCK_LOCKED) {
#if defined(MULTIPROCESSOR) /* { */
if (alp->lock_holder == cpu_id) {
SLOCK_WHERE("simple_lock: locking against myself\n",
alp, id, l);
goto out;
}
#else
SLOCK_WHERE("simple_lock: lock held\n", alp, id, l);
goto out;
#endif /* MULTIPROCESSOR */ /* } */
}
#if defined(MULTIPROCESSOR) /* { */
/* Acquire the lock before modifying any fields. */
cpu_simple_lock(alp);
#else
alp->lock_data = SIMPLELOCK_LOCKED;
#endif /* } */
alp->lock_file = id;
alp->lock_line = l;
alp->lock_holder = cpu_id;
SLOCK_LIST_LOCK();
/* XXX Cast away volatile */
TAILQ_INSERT_TAIL(&simplelock_list, (struct simplelock *)alp, list);
SLOCK_LIST_UNLOCK();
SLOCK_COUNT(1);
out:
splx(s);
}
int
_simple_lock_try(alp, id, l)
__volatile struct simplelock *alp;
const char *id;
int l;
{
cpuid_t cpu_id = cpu_number();
int s, rv = 0;
s = splhigh();
/*
* MULTIPROCESSOR case: This is `safe' since if it's not us, we
* don't take any action.
*/
#if defined(MULTIPROCESSOR) /* { */
if ((rv = cpu_simple_lock_try(alp)) == 0) {
if (alp->lock_holder == cpu_id)
SLOCK_WHERE("simple_lock_try: locking against myself\n",
alp, id, l);
goto out;
}
#else
if (alp->lock_data == SIMPLELOCK_LOCKED) {
SLOCK_WHERE("simple_lock_try: lock held\n", alp, id, l);
goto out;
}
alp->lock_data = SIMPLELOCK_LOCKED;
#endif /* MULTIPROCESSOR */ /* } */
/*
* At this point, we have acquired the lock.
*/
rv = 1;
alp->lock_file = id;
alp->lock_line = l;
alp->lock_holder = cpu_id;
SLOCK_LIST_LOCK();
/* XXX Cast away volatile. */
TAILQ_INSERT_TAIL(&simplelock_list, (struct simplelock *)alp, list);
SLOCK_LIST_UNLOCK();
SLOCK_COUNT(1);
out:
splx(s);
return (rv);
}
void
_simple_unlock(alp, id, l)
__volatile struct simplelock *alp;
const char *id;
int l;
{
int s;
s = splhigh();
/*
* MULTIPROCESSOR case: This is `safe' because we think we hold
* the lock, and if we don't, we don't take any action.
*/
if (alp->lock_data == SIMPLELOCK_UNLOCKED) {
SLOCK_WHERE("simple_unlock: lock not held\n",
alp, id, l);
goto out;
}
SLOCK_LIST_LOCK();
TAILQ_REMOVE(&simplelock_list, alp, list);
SLOCK_LIST_UNLOCK();
SLOCK_COUNT(-1);
alp->list.tqe_next = NULL; /* sanity */
alp->list.tqe_prev = NULL; /* sanity */
alp->unlock_file = id;
alp->unlock_line = l;
#if defined(MULTIPROCESSOR) /* { */
alp->lock_holder = LK_NOCPU;
/* Now that we've modified all fields, release the lock. */
cpu_simple_unlock(alp);
#else
alp->lock_data = SIMPLELOCK_UNLOCKED;
#endif /* } */
out:
splx(s);
}
void
simple_lock_dump()
{
struct simplelock *alp;
int s;
s = splhigh();
SLOCK_LIST_LOCK();
lock_printf("all simple locks:\n");
for (alp = TAILQ_FIRST(&simplelock_list); alp != NULL;
alp = TAILQ_NEXT(alp, list)) {
lock_printf("%p CPU %lu %s:%d\n", alp, alp->lock_holder,
alp->lock_file, alp->lock_line);
}
SLOCK_LIST_UNLOCK();
splx(s);
}
void
simple_lock_freecheck(start, end)
void *start, *end;
{
struct simplelock *alp;
int s;
s = splhigh();
SLOCK_LIST_LOCK();
for (alp = TAILQ_FIRST(&simplelock_list); alp != NULL;
alp = TAILQ_NEXT(alp, list)) {
if ((void *)alp >= start && (void *)alp < end) {
lock_printf("freeing simple_lock %p CPU %lu %s:%d\n",
alp, alp->lock_holder, alp->lock_file,
alp->lock_line);
SLOCK_DEBUGGER();
}
}
SLOCK_LIST_UNLOCK();
splx(s);
}
#endif /* LOCKDEBUG */ /* } */
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