kern_lock.c

来自「基于组件方式开发操作系统的OSKIT源代码」· C语言 代码 · 共 1,249 行 · 第 1/3 页

/*	$NetBSD: kern_lock.c,v 1.50 2000/11/22 06:31:23 thorpej 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. 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(const char *fmt, ...)
    __attribute__((__format__(__printf__,1,2)));

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)						\
	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 (/*CONSTCOND*/0)
#else
#define COUNT(lkp, p, cpu_id, x)
#define COUNT_CPU(cpu_id, x)
#endif /* LOCKDEBUG || DIAGNOSTIC */ /* } */

#ifndef SPINLOCK_INTERLOCK_RELEASE_HOOK		/* from <machine/lock.h> */
#define	SPINLOCK_INTERLOCK_RELEASE_HOOK		/* nothing */
#endif

#define	INTERLOCK_ACQUIRE(lkp, flags, s)				\
do {									\
	if ((flags) & LK_SPIN)						\
		s = splsched();						\
	simple_lock(&(lkp)->lk_interlock);				\
} while (0)

#define	INTERLOCK_RELEASE(lkp, flags, s)				\
do {									\
	simple_unlock(&(lkp)->lk_interlock);				\
	if ((flags) & LK_SPIN) {					\
		splx(s);						\
		SPINLOCK_INTERLOCK_RELEASE_HOOK;			\
	}								\
} while (0)

#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) {						\
		printf("LK_SPIN spinout, excl %d, share %d\n",		\
		    lkp->lk_exclusivecount, lkp->lk_sharecount);	\
		if (lkp->lk_exclusivecount)				\
			printf("held by CPU %lu\n",			\
			    (u_long) lkp->lk_cpu);			\
		if (lkp->lk_lock_file)					\
			printf("last locked at %s:%d\n",		\
			    lkp->lk_lock_file, lkp->lk_lock_line);	\
		if (lkp->lk_unlock_file)				\
			printf("last unlocked at %s:%d\n",		\
			    lkp->lk_unlock_file, lkp->lk_unlock_line);	\
		SPINLOCK_SPINCHECK_DEBUGGER;				\
	}								\
} while (0)
#else
#define	SPINLOCK_SPINCHECK_DECL			/* nothing */
#define	SPINLOCK_SPINCHECK			/* nothing */
#endif /* LOCKDEBUG && DDB */

/*
 * Acquire a resource.
 */
#define ACQUIRE(lkp, error, extflags, drain, wanted)			\
	if ((extflags) & LK_SPIN) {					\
		int interlocked;					\
		SPINLOCK_SPINCHECK_DECL;				\
									\
		if ((drain) == 0)					\
			(lkp)->lk_waitcount++;				\
		for (interlocked = 1;;) {				\
			SPINLOCK_SPINCHECK;				\
			if (wanted) {					\
				if (interlocked) {			\
					INTERLOCK_RELEASE((lkp),	\
					    LK_SPIN, s);		\
					interlocked = 0;		\
				}					\
			} else if (interlocked) {			\
				break;					\
			} else {					\
				INTERLOCK_ACQUIRE((lkp), LK_SPIN, s);	\
				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++;			\
			/* XXX Cast away volatile. */			\
			error = ltsleep((drain) ? &(lkp)->lk_flags :	\
			    (void *)(lkp), (lkp)->lk_prio,		\
			    (lkp)->lk_wmesg, (lkp)->lk_timo,		\
			    &(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 (/*CONSTCOND*/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 (/*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, ...)
{
	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(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 */
#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, lock_type = 0;

	INTERLOCK_ACQUIRE(lkp, lkp->lk_flags, s);
	if (lkp->lk_exclusivecount != 0)
		lock_type = LK_EXCLUSIVE;
	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.