/* $NetBSD: kern_lock.c,v 1.85.4.1 2005/04/29 11:29:23 kent Exp $ */
/*-
* Copyright (c) 1999, 2000 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. 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/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: kern_lock.c,v 1.85.4.1 2005/04/29 11:29:23 kent Exp $");
#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(const char *fmt, ...)
__attribute__((__format__(__printf__,1,2)));
static int acquire(__volatile struct lock **, int *, int, int, int);
int lock_debug_syslog = 0; /* defaults to printf, but can be patched */
#ifdef DDB
#include <ddb/ddbvar.h>
#include <machine/db_machdep.h>
#include <ddb/db_command.h>
#include <ddb/db_interface.h>
#endif
#endif /* defined(LOCKDEBUG) */
#if defined(MULTIPROCESSOR)
struct simplelock kernel_lock;
#endif
/*
* Locking primitives implementation.
* Locks provide shared/exclusive synchronization.
*/
#if defined(LOCKDEBUG) || defined(DIAGNOSTIC) /* { */
#if defined(MULTIPROCESSOR) /* { */
#define COUNT_CPU(cpu_id, x) \
curcpu()->ci_spin_locks += (x)
#else
u_long spin_locks;
#define COUNT_CPU(cpu_id, x) spin_locks += (x)
#endif /* MULTIPROCESSOR */ /* } */
#define COUNT(lkp, l, cpu_id, x) \
do { \
if ((lkp)->lk_flags & LK_SPIN) \
COUNT_CPU((cpu_id), (x)); \
else \
(l)->l_locks += (x); \
} while (/*CONSTCOND*/0)
#else
#define COUNT(lkp, p, cpu_id, x)
#define COUNT_CPU(cpu_id, x)
#endif /* LOCKDEBUG || DIAGNOSTIC */ /* } */
#ifndef SPINLOCK_SPIN_HOOK /* from <machine/lock.h> */
#define SPINLOCK_SPIN_HOOK /* nothing */
#endif
#define INTERLOCK_ACQUIRE(lkp, flags, s) \
do { \
if ((flags) & LK_SPIN) \
s = spllock(); \
simple_lock(&(lkp)->lk_interlock); \
} while (/*CONSTCOND*/ 0)
#define INTERLOCK_RELEASE(lkp, flags, s) \
do { \
simple_unlock(&(lkp)->lk_interlock); \
if ((flags) & LK_SPIN) \
splx(s); \
} while (/*CONSTCOND*/ 0)
#ifdef DDB /* { */
#ifdef MULTIPROCESSOR
int simple_lock_debugger = 1; /* more serious on MP */
#else
int simple_lock_debugger = 0;
#endif
#define SLOCK_DEBUGGER() if (simple_lock_debugger) Debugger()
#define SLOCK_TRACE() \
db_stack_trace_print((db_expr_t)__builtin_frame_address(0), \
TRUE, 65535, "", lock_printf);
#else
#define SLOCK_DEBUGGER() /* nothing */
#define SLOCK_TRACE() /* nothing */
#endif /* } */
#if defined(LOCKDEBUG)
#if defined(DDB)
#define SPINLOCK_SPINCHECK_DEBUGGER Debugger()
#else
#define SPINLOCK_SPINCHECK_DEBUGGER /* nothing */
#endif
#define SPINLOCK_SPINCHECK_DECL \
/* 32-bits of count -- wrap constitutes a "spinout" */ \
uint32_t __spinc = 0
#define SPINLOCK_SPINCHECK \
do { \
if (++__spinc == 0) { \
lock_printf("LK_SPIN spinout, excl %d, share %d\n", \
lkp->lk_exclusivecount, lkp->lk_sharecount); \
if (lkp->lk_exclusivecount) \
lock_printf("held by CPU %lu\n", \
(u_long) lkp->lk_cpu); \
if (lkp->lk_lock_file) \
lock_printf("last locked at %s:%d\n", \
lkp->lk_lock_file, lkp->lk_lock_line); \
if (lkp->lk_unlock_file) \
lock_printf("last unlocked at %s:%d\n", \
lkp->lk_unlock_file, lkp->lk_unlock_line); \
SLOCK_TRACE(); \
SPINLOCK_SPINCHECK_DEBUGGER; \
} \
} while (/*CONSTCOND*/ 0)
#else
#define SPINLOCK_SPINCHECK_DECL /* nothing */
#define SPINLOCK_SPINCHECK /* nothing */
#endif /* LOCKDEBUG && DDB */
/*
* Acquire a resource.
*/
static int
acquire(__volatile struct lock **lkpp, int *s, int extflags,
int drain, int wanted)
{
int error;
__volatile struct lock *lkp = *lkpp;
KASSERT(drain || (wanted & LK_WAIT_NONZERO) == 0);
if (extflags & LK_SPIN) {
int interlocked;
SPINLOCK_SPINCHECK_DECL;
if (!drain) {
lkp->lk_waitcount++;
lkp->lk_flags |= LK_WAIT_NONZERO;
}
for (interlocked = 1;;) {
SPINLOCK_SPINCHECK;
if ((lkp->lk_flags & wanted) != 0) {
if (interlocked) {
INTERLOCK_RELEASE(lkp, LK_SPIN, *s);
interlocked = 0;
}
SPINLOCK_SPIN_HOOK;
} else if (interlocked) {
break;
} else {
INTERLOCK_ACQUIRE(lkp, LK_SPIN, *s);
interlocked = 1;
}
}
if (!drain) {
lkp->lk_waitcount--;
if (lkp->lk_waitcount == 0)
lkp->lk_flags &= ~LK_WAIT_NONZERO;
}
KASSERT((lkp->lk_flags & wanted) == 0);
error = 0; /* sanity */
} else {
for (error = 0; (lkp->lk_flags & wanted) != 0; ) {
if (drain)
lkp->lk_flags |= LK_WAITDRAIN;
else {
lkp->lk_waitcount++;
lkp->lk_flags |= LK_WAIT_NONZERO;
}
/* XXX Cast away volatile. */
error = ltsleep(drain ?
(void *)&lkp->lk_flags :
(void *)lkp, lkp->lk_prio,
lkp->lk_wmesg, lkp->lk_timo, &lkp->lk_interlock);
if (!drain) {
lkp->lk_waitcount--;
if (lkp->lk_waitcount == 0)
lkp->lk_flags &= ~LK_WAIT_NONZERO;
}
if (error)
break;
if (extflags & LK_SLEEPFAIL) {
error = ENOLCK;
break;
}
if (lkp->lk_newlock != NULL) {
simple_lock(&lkp->lk_newlock->lk_interlock);
simple_unlock(&lkp->lk_interlock);
if (lkp->lk_waitcount == 0)
wakeup((void *)&lkp->lk_newlock);
*lkpp = lkp = lkp->lk_newlock;
}
}
}
return error;
}
#define SETHOLDER(lkp, pid, lid, cpu_id) \
do { \
if ((lkp)->lk_flags & LK_SPIN) \
(lkp)->lk_cpu = cpu_id; \
else { \
(lkp)->lk_lockholder = pid; \
(lkp)->lk_locklwp = lid; \
} \
} while (/*CONSTCOND*/0)
#define WEHOLDIT(lkp, pid, lid, cpu_id) \
(((lkp)->lk_flags & LK_SPIN) != 0 ? \
((lkp)->lk_cpu == (cpu_id)) : \
((lkp)->lk_lockholder == (pid) && (lkp)->lk_locklwp == (lid)))
#define WAKEUP_WAITER(lkp) \
do { \
if (((lkp)->lk_flags & (LK_SPIN | LK_WAIT_NONZERO)) == \
LK_WAIT_NONZERO) { \
/* XXX Cast away volatile. */ \
wakeup((void *)(lkp)); \
} \
} while (/*CONSTCOND*/0)
#if defined(LOCKDEBUG) /* { */
#if defined(MULTIPROCESSOR) /* { */
struct simplelock spinlock_list_slock = SIMPLELOCK_INITIALIZER;
#define SPINLOCK_LIST_LOCK() \
__cpu_simple_lock(&spinlock_list_slock.lock_data)
#define SPINLOCK_LIST_UNLOCK() \
__cpu_simple_unlock(&spinlock_list_slock.lock_data)
#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 = spllock(); \
SPINLOCK_LIST_LOCK(); \
/* XXX Cast away volatile. */ \
TAILQ_INSERT_TAIL(&spinlock_list, (struct lock *)(lkp), \
lk_list); \
SPINLOCK_LIST_UNLOCK(); \
splx(s); \
} \
} while (/*CONSTCOND*/0)
#define DONTHAVEIT(lkp) \
do { \
if ((lkp)->lk_flags & LK_SPIN) { \
int s = spllock(); \
SPINLOCK_LIST_LOCK(); \
/* XXX Cast away volatile. */ \
TAILQ_REMOVE(&spinlock_list, (struct lock *)(lkp), \
lk_list); \
SPINLOCK_LIST_UNLOCK(); \
splx(s); \
} \
} while (/*CONSTCOND*/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
lock_printf(const char *fmt, ...)
{
char b[150];
va_list ap;
va_start(ap, fmt);
if (lock_debug_syslog)
vlog(LOG_DEBUG, fmt, ap);
else {
vsnprintf(b, sizeof(b), fmt, ap);
printf_nolog("%s", b);
}
va_end(ap);
}
#endif /* LOCKDEBUG */
/*
* Transfer any waiting processes from one lock to another.
*/
void
transferlockers(struct lock *from, struct lock *to)
{
KASSERT(from != to);
KASSERT((from->lk_flags & LK_WAITDRAIN) == 0);
if (from->lk_waitcount == 0)
return;
from->lk_newlock = to;
wakeup((void *)from);
tsleep((void *)&from->lk_newlock, from->lk_prio, "lkxfer", 0);
from->lk_newlock = NULL;
from->lk_flags &= ~(LK_WANT_EXCL | LK_WANT_UPGRADE);
KASSERT(from->lk_waitcount == 0);
}
/*
* Initialize a lock; required before use.
*/
void
lockinit(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_newlock = NULL;
lkp->lk_prio = prio;
lkp->lk_timo = timo;
}
lkp->lk_wmesg = wmesg; /* just a name for spin locks */
#if defined(LOCKDEBUG)
lkp->lk_lock_file = NULL;
lkp->lk_unlock_file = NULL;
#endif
}
/*
* Determine the status of a lock.
*/
int
lockstatus(struct lock *lkp)
{
int s = 0; /* XXX: gcc */
int lock_type = 0;
struct lwp *l = curlwp; /* XXX */
pid_t pid;
lwpid_t lid;
cpuid_t cpu_id;
if ((lkp->lk_flags & LK_SPIN) || l == NULL) {
cpu_id = cpu_number();
pid = LK_KERNPROC;
lid = 0;
} else {
cpu_id = LK_NOCPU;
pid = l->l_proc->p_pid;
lid = l->l_lid;
}
INTERLOCK_ACQUIRE(lkp, lkp->lk_flags, s);
if (lkp->lk_exclusivecount != 0) {
if (WEHOLDIT(lkp, pid, lid, cpu_id))
lock_type = LK_EXCLUSIVE;
else
lock_type = LK_EXCLOTHER;
} else if (lkp->lk_sharecount != 0)
lock_type = LK_SHARED;
INTERLOCK_RELEASE(lkp, lkp->lk_flags, s);
return (lock_type);
}
#if defined(LOCKDEBUG) || defined(DIAGNOSTIC)
/*
* Make sure no spin locks are held by a CPU that is about
* to context switch.
*/
void
spinlock_switchcheck(void)
{
u_long cnt;
int s;
s = spllock();
#if defined(MULTIPROCESSOR)
cnt = curcpu()->ci_spin_locks;
#else
cnt = spin_locks;
#endif
splx(s);
if (cnt != 0)
panic("spinlock_switchcheck: CPU %lu has %lu spin locks",
(u_long) cpu_number(), cnt);
}
#endif /* LOCKDEBUG || DIAGNOSTIC */
/*
* Locks and IPLs (interrupt priority levels):
*
* Locks which may be taken from interrupt context must be handled
* very carefully; you must spl to the highest IPL where the lock
* is needed before acquiring the lock.
*
* It is also important to avoid deadlock, since certain (very high
* priority) interrupts are often needed to keep the system as a whole
* from deadlocking, and must not be blocked while you are spinning
* waiting for a lower-priority lock.
*
* In addition, the lock-debugging hooks themselves need to use locks!
*
* A raw __cpu_simple_lock may be used from interrupts are long as it
* is acquired and held at a single IPL.
*
* A simple_lock (which is a __cpu_simple_lock wrapped with some
* debugging hooks) may be used at or below spllock(), which is
* typically at or just below splhigh() (i.e. blocks everything
* but certain machine-dependent extremely high priority interrupts).
*
* spinlockmgr spinlocks should be used at or below splsched().
*
* Some platforms may have interrupts of higher priority than splsched(),
* including hard serial interrupts, inter-processor interrupts, and
* kernel debugger traps.
*/
/*
* XXX XXX kludge around another kludge..
*
* vfs_shutdown() may be called from interrupt context, either as a result
* of a panic, or from the debugger. It proceeds to call
* sys_sync(&proc0, ...), pretending its running on behalf of proc0
*
* We would like to make an attempt to sync the filesystems in this case, so
* if this happens, we treat attempts to acquire locks specially.
* All locks are acquired on behalf of proc0.
*
* If we've already paniced, we don't block waiting for locks, but
* just barge right ahead since we're already going down in flames.
*/
/*
* 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
#if defined(LOCKDEBUG)
_lockmgr(__volatile struct lock *lkp, u_int flags,
struct simplelock *interlkp, const char *file, int line)
#else
lockmgr(__volatile struct lock *lkp, u_int flags,
struct simplelock *interlkp)
#endif
{
int error;
pid_t pid;
lwpid_t lid;
int extflags;
cpuid_t cpu_id;
struct lwp *l = curlwp;
int lock_shutdown_noblock = 0;
int s = 0;
error = 0;
/* LK_RETRY is for vn_lock, not for lockmgr. */
KASSERT((flags & LK_RETRY) == 0);
INTERLOCK_ACQUIRE(lkp, lkp->lk_flags, s);
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");
#endif /* } */
if (extflags & LK_SPIN) {
pid = LK_KERNPROC;
lid = 0;
} else {
if (l == NULL) {
if (!doing_shutdown) {
panic("lockmgr: no context");
} else {
l = &lwp0;
if (panicstr && (!(flags & LK_NOWAIT))) {
flags |= LK_NOWAIT;
lock_shutdown_noblock = 1;
}
}
}
lid = l->l_lid;
pid = l->l_proc->p_pid;
}
cpu_id = cpu_number();
/*
* 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)) {
#ifdef DIAGNOSTIC /* { */
if (lkp->lk_flags & LK_DRAINED)
panic("lockmgr: using decommissioned lock");
if ((flags & LK_TYPE_MASK) != LK_RELEASE ||
WEHOLDIT(lkp, pid, lid, cpu_id) == 0)
panic("lockmgr: non-release on draining lock: %d",
flags & LK_TYPE_MASK);
#endif /* DIAGNOSTIC */ /* } */
lkp->lk_flags &= ~LK_DRAINING;
if ((flags & LK_REENABLE) == 0)
lkp->lk_flags |= LK_DRAINED;
}
switch (flags & LK_TYPE_MASK) {
case LK_SHARED:
if (WEHOLDIT(lkp, pid, lid, 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.
*/
error = acquire(&lkp, &s, extflags, 0,
LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE);
if (error)
break;
lkp->lk_sharecount++;
lkp->lk_flags |= LK_SHARE_NONZERO;
COUNT(lkp, l, 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++;
lkp->lk_flags |= LK_SHARE_NONZERO;
COUNT(lkp, l, cpu_id, 1);
/* fall into downgrade */
case LK_DOWNGRADE:
if (WEHOLDIT(lkp, pid, lid, cpu_id) == 0 ||
lkp->lk_exclusivecount == 0)
panic("lockmgr: not holding exclusive lock");
lkp->lk_sharecount += lkp->lk_exclusivecount;
lkp->lk_flags |= LK_SHARE_NONZERO;
lkp->lk_exclusivecount = 0;
lkp->lk_recurselevel = 0;
lkp->lk_flags &= ~LK_HAVE_EXCL;
SETHOLDER(lkp, LK_NOPROC, 0, LK_NOCPU);
#if defined(LOCKDEBUG)
lkp->lk_unlock_file = file;
lkp->lk_unlock_line = line;
#endif
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--;
if (lkp->lk_sharecount == 0)
lkp->lk_flags &= ~LK_SHARE_NONZERO;
COUNT(lkp, l, 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, lid, cpu_id) || lkp->lk_sharecount <= 0)
panic("lockmgr: upgrade exclusive lock");
lkp->lk_sharecount--;
if (lkp->lk_sharecount == 0)
lkp->lk_flags &= ~LK_SHARE_NONZERO;
COUNT(lkp, l, 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;
error = acquire(&lkp, &s, extflags, 0, LK_SHARE_NONZERO);
lkp->lk_flags &= ~LK_WANT_UPGRADE;
if (error) {
WAKEUP_WAITER(lkp);
break;
}
lkp->lk_flags |= LK_HAVE_EXCL;
SETHOLDER(lkp, pid, lid, cpu_id);
#if defined(LOCKDEBUG)
lkp->lk_lock_file = file;
lkp->lk_lock_line = line;
#endif
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, l, 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, lid, 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, l, 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 |
LK_SHARE_NONZERO))) {
error = EBUSY;
break;
}
/*
* Try to acquire the want_exclusive flag.
*/
error = acquire(&lkp, &s, extflags, 0,
LK_HAVE_EXCL | LK_WANT_EXCL);
if (error)
break;
lkp->lk_flags |= LK_WANT_EXCL;
/*
* Wait for shared locks and upgrades to finish.
*/
error = acquire(&lkp, &s, extflags, 0,
LK_HAVE_EXCL | LK_WANT_UPGRADE | LK_SHARE_NONZERO);
lkp->lk_flags &= ~LK_WANT_EXCL;
if (error) {
WAKEUP_WAITER(lkp);
break;
}
lkp->lk_flags |= LK_HAVE_EXCL;
SETHOLDER(lkp, pid, lid, cpu_id);
#if defined(LOCKDEBUG)
lkp->lk_lock_file = file;
lkp->lk_lock_line = line;
#endif
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, l, cpu_id, 1);
break;
case LK_RELEASE:
if (lkp->lk_exclusivecount != 0) {
if (WEHOLDIT(lkp, pid, lid, 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, l, cpu_id, -1);
if (lkp->lk_exclusivecount == 0) {
lkp->lk_flags &= ~LK_HAVE_EXCL;
SETHOLDER(lkp, LK_NOPROC, 0, LK_NOCPU);
#if defined(LOCKDEBUG)
lkp->lk_unlock_file = file;
lkp->lk_unlock_line = line;
#endif
DONTHAVEIT(lkp);
}
} else if (lkp->lk_sharecount != 0) {
lkp->lk_sharecount--;
if (lkp->lk_sharecount == 0)
lkp->lk_flags &= ~LK_SHARE_NONZERO;
COUNT(lkp, l, cpu_id, -1);
}
#ifdef DIAGNOSTIC
else
panic("lockmgr: release of unlocked lock!");
#endif
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, lid, 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 |
LK_SHARE_NONZERO | LK_WAIT_NONZERO))) {
error = EBUSY;
break;
}
error = acquire(&lkp, &s, extflags, 1,
LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE |
LK_SHARE_NONZERO | LK_WAIT_NONZERO);
if (error)
break;
lkp->lk_flags |= LK_DRAINING | LK_HAVE_EXCL;
SETHOLDER(lkp, pid, lid, cpu_id);
#if defined(LOCKDEBUG)
lkp->lk_lock_file = file;
lkp->lk_lock_line = line;
#endif
HAVEIT(lkp);
lkp->lk_exclusivecount = 1;
/* XXX unlikely that we'd want this */
if (extflags & LK_SETRECURSE)
lkp->lk_recurselevel = 1;
COUNT(lkp, l, cpu_id, 1);
break;
default:
INTERLOCK_RELEASE(lkp, lkp->lk_flags, s);
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 |
LK_SHARE_NONZERO | LK_WAIT_NONZERO)) == 0)) {
lkp->lk_flags &= ~LK_WAITDRAIN;
wakeup((void *)&lkp->lk_flags);
}
/*
* Note that this panic will be a recursive panic, since
* we only set lock_shutdown_noblock above if panicstr != NULL.
*/
if (error && lock_shutdown_noblock)
panic("lockmgr: deadlock (see previous panic)");
INTERLOCK_RELEASE(lkp, lkp->lk_flags, s);
return (error);
}
/*
* For a recursive spinlock held one or more times by the current CPU,
* release all N locks, and return N.
* Intended for use in mi_switch() shortly before context switching.
*/
int
#if defined(LOCKDEBUG)
_spinlock_release_all(__volatile struct lock *lkp, const char *file, int line)
#else
spinlock_release_all(__volatile struct lock *lkp)
#endif
{
int s, count;
cpuid_t cpu_id;
KASSERT(lkp->lk_flags & LK_SPIN);
INTERLOCK_ACQUIRE(lkp, LK_SPIN, s);
cpu_id = cpu_number();
count = lkp->lk_exclusivecount;
if (count != 0) {
#ifdef DIAGNOSTIC
if (WEHOLDIT(lkp, 0, 0, cpu_id) == 0) {
panic("spinlock_release_all: processor %lu, not "
"exclusive lock holder %lu "
"unlocking", (long)cpu_id, lkp->lk_cpu);
}
#endif
lkp->lk_recurselevel = 0;
lkp->lk_exclusivecount = 0;
COUNT_CPU(cpu_id, -count);
lkp->lk_flags &= ~LK_HAVE_EXCL;
SETHOLDER(lkp, LK_NOPROC, 0, LK_NOCPU);
#if defined(LOCKDEBUG)
lkp->lk_unlock_file = file;
lkp->lk_unlock_line = line;
#endif
DONTHAVEIT(lkp);
}
#ifdef DIAGNOSTIC
else if (lkp->lk_sharecount != 0)
panic("spinlock_release_all: release of shared lock!");
else
panic("spinlock_release_all: release of unlocked lock!");
#endif
INTERLOCK_RELEASE(lkp, LK_SPIN, s);
return (count);
}
/*
* For a recursive spinlock held one or more times by the current CPU,
* release all N locks, and return N.
* Intended for use in mi_switch() right after resuming execution.
*/
void
#if defined(LOCKDEBUG)
_spinlock_acquire_count(__volatile struct lock *lkp, int count,
const char *file, int line)
#else
spinlock_acquire_count(__volatile struct lock *lkp, int count)
#endif
{
int s, error;
cpuid_t cpu_id;
KASSERT(lkp->lk_flags & LK_SPIN);
INTERLOCK_ACQUIRE(lkp, LK_SPIN, s);
cpu_id = cpu_number();
#ifdef DIAGNOSTIC
if (WEHOLDIT(lkp, LK_NOPROC, 0, cpu_id))
panic("spinlock_acquire_count: processor %lu already holds lock", (long)cpu_id);
#endif
/*
* Try to acquire the want_exclusive flag.
*/
error = acquire(&lkp, &s, LK_SPIN, 0, LK_HAVE_EXCL | LK_WANT_EXCL);
lkp->lk_flags |= LK_WANT_EXCL;
/*
* Wait for shared locks and upgrades to finish.
*/
error = acquire(&lkp, &s, LK_SPIN, 0,
LK_HAVE_EXCL | LK_SHARE_NONZERO | LK_WANT_UPGRADE);
lkp->lk_flags &= ~LK_WANT_EXCL;
lkp->lk_flags |= LK_HAVE_EXCL;
SETHOLDER(lkp, LK_NOPROC, 0, cpu_id);
#if defined(LOCKDEBUG)
lkp->lk_lock_file = file;
lkp->lk_lock_line = line;
#endif
HAVEIT(lkp);
if (lkp->lk_exclusivecount != 0)
panic("lockmgr: non-zero exclusive count");
lkp->lk_exclusivecount = count;
lkp->lk_recurselevel = 1;
COUNT_CPU(cpu_id, count);
INTERLOCK_RELEASE(lkp, lkp->lk_flags, s);
}
/*
* Print out information about state of a lock. Used by VOP_PRINT
* routines to display ststus about contained locks.
*/
void
lockmgr_printinfo(__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.%d", lkp->lk_lockholder,
lkp->lk_locklwp);
} 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.lock_data)
#define SLOCK_LIST_UNLOCK() \
__cpu_simple_unlock(&simplelock_list_slock.lock_data)
#define SLOCK_COUNT(x) \
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 MULTIPROCESSOR
#define SLOCK_MP() lock_printf("on CPU %ld\n", \
(u_long) cpu_number())
#else
#define SLOCK_MP() /* nothing */
#endif
#define SLOCK_WHERE(str, alp, id, l) \
do { \
lock_printf("\n"); \
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_TRACE() \
SLOCK_DEBUGGER(); \
} while (/*CONSTCOND*/0)
/*
* Simple lock functions so that the debugger can see from whence
* they are being called.
*/
void
simple_lock_init(struct simplelock *alp)
{
#if defined(MULTIPROCESSOR) /* { */
__cpu_simple_lock_init(&alp->lock_data);
#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 = LK_NOCPU;
}
void
_simple_lock(__volatile struct simplelock *alp, const char *id, int l)
{
cpuid_t cpu_id = cpu_number();
int s;
s = spllock();
/*
* 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. */
splx(s);
__cpu_simple_lock(&alp->lock_data);
s = spllock();
#else
alp->lock_data = __SIMPLELOCK_LOCKED;
#endif /* } */
if (alp->lock_holder != LK_NOCPU) {
SLOCK_WHERE("simple_lock: uninitialized lock\n",
alp, id, l);
}
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_held(__volatile struct simplelock *alp)
{
#if defined(MULTIPROCESSOR) || defined(DIAGNOSTIC)
cpuid_t cpu_id = cpu_number();
#endif
int s, locked = 0;
s = spllock();
#if defined(MULTIPROCESSOR)
if (__cpu_simple_lock_try(&alp->lock_data) == 0)
locked = (alp->lock_holder == cpu_id);
else
__cpu_simple_unlock(&alp->lock_data);
#else
if (alp->lock_data == __SIMPLELOCK_LOCKED) {
locked = 1;
KASSERT(alp->lock_holder == cpu_id);
}
#endif
splx(s);
return (locked);
}
int
_simple_lock_try(__volatile struct simplelock *alp, const char *id, int l)
{
cpuid_t cpu_id = cpu_number();
int s, rv = 0;
s = spllock();
/*
* 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->lock_data)) == 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(__volatile struct simplelock *alp, const char *id, int l)
{
int s;
s = spllock();
/*
* 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->lock_data);
#else
alp->lock_data = __SIMPLELOCK_UNLOCKED;
KASSERT(alp->lock_holder == cpu_number());
alp->lock_holder = LK_NOCPU;
#endif /* } */
out:
splx(s);
}
void
simple_lock_dump(void)
{
struct simplelock *alp;
int s;
s = spllock();
SLOCK_LIST_LOCK();
lock_printf("all simple locks:\n");
TAILQ_FOREACH(alp, &simplelock_list, 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(void *start, void *end)
{
struct simplelock *alp;
int s;
s = spllock();
SLOCK_LIST_LOCK();
TAILQ_FOREACH(alp, &simplelock_list, 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);
}
/*
* We must be holding exactly one lock: the sched_lock.
*/
void
simple_lock_switchcheck(void)
{
simple_lock_only_held(&sched_lock, "switching");
}
void
simple_lock_only_held(volatile struct simplelock *lp, const char *where)
{
struct simplelock *alp;
cpuid_t cpu_id = cpu_number();
int s;
if (lp) {
LOCK_ASSERT(simple_lock_held(lp));
}
s = spllock();
SLOCK_LIST_LOCK();
TAILQ_FOREACH(alp, &simplelock_list, list) {
if (alp == lp)
continue;
#if defined(MULTIPROCESSOR)
if (alp == &kernel_lock)
continue;
#endif /* defined(MULTIPROCESSOR) */
if (alp->lock_holder == cpu_id)
break;
}
SLOCK_LIST_UNLOCK();
splx(s);
if (alp != NULL) {
lock_printf("\n%s with held simple_lock %p "
"CPU %lu %s:%d\n",
where, alp, alp->lock_holder, alp->lock_file,
alp->lock_line);
SLOCK_TRACE();
SLOCK_DEBUGGER();
}
}
#endif /* LOCKDEBUG */ /* } */
#if defined(MULTIPROCESSOR)
/*
* Functions for manipulating the kernel_lock. We put them here
* so that they show up in profiles.
*/
/*
* splbiglock: block IPLs which need to grab kernel_lock.
* XXX splvm or splaudio should be enough.
*/
#if !defined(__HAVE_SPLBIGLOCK)
#define splbiglock() splclock()
#endif
void
_kernel_lock_init(void)
{
simple_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(int flag)
{
struct cpu_info *ci = curcpu();
SCHED_ASSERT_UNLOCKED();
if (ci->ci_data.cpu_biglock_count > 0) {
LOCK_ASSERT(simple_lock_held(&kernel_lock));
ci->ci_data.cpu_biglock_count++;
} else {
int s;
s = splbiglock();
while (!simple_lock_try(&kernel_lock)) {
splx(s);
SPINLOCK_SPIN_HOOK;
s = splbiglock();
}
ci->ci_data.cpu_biglock_count++;
splx(s);
}
}
void
_kernel_unlock(void)
{
struct cpu_info *ci = curcpu();
int s;
KASSERT(ci->ci_data.cpu_biglock_count > 0);
s = splbiglock();
if ((--ci->ci_data.cpu_biglock_count) == 0)
simple_unlock(&kernel_lock);
splx(s);
}
/*
* Acquire/release the kernel_lock on behalf of a process. Intended for
* use in the top half of the kernel.
*/
void
_kernel_proc_lock(struct lwp *l)
{
SCHED_ASSERT_UNLOCKED();
_kernel_lock(0);
}
void
_kernel_proc_unlock(struct lwp *l)
{
_kernel_unlock();
}
int
_kernel_lock_release_all()
{
struct cpu_info *ci = curcpu();
int hold_count;
hold_count = ci->ci_data.cpu_biglock_count;
if (hold_count) {
int s;
s = splbiglock();
ci->ci_data.cpu_biglock_count = 0;
simple_unlock(&kernel_lock);
splx(s);
}
return hold_count;
}
void
_kernel_lock_acquire_count(int hold_count)
{
KASSERT(curcpu()->ci_data.cpu_biglock_count == 0);
if (hold_count != 0) {
struct cpu_info *ci = curcpu();
int s;
s = splbiglock();
while (!simple_lock_try(&kernel_lock)) {
splx(s);
SPINLOCK_SPIN_HOOK;
s = splbiglock();
}
ci->ci_data.cpu_biglock_count = hold_count;
splx(s);
}
}
#if defined(DEBUG)
void
_kernel_lock_assert_locked()
{
LOCK_ASSERT(simple_lock_held(&kernel_lock));
}
#endif
#endif /* MULTIPROCESSOR */
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