Import 4.4BSD-Lite2 onto CSRG branch

1 files changed, 180 insertions, 0 deletions

diff --git a/sys/sys/lockmgr.h b/sys/sys/lockmgr.h
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+/* 
+ * 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.
+ *
+ *	@(#)lock.h	8.12 (Berkeley) 5/19/95
+ */
+
+#ifndef	_LOCK_H_
+#define	_LOCK_H_
+
+/*
+ * The general lock structure.  Provides for multiple shared locks,
+ * upgrading from shared to exclusive, and sleeping until the lock
+ * can be gained. The simple locks are defined in <machine/param.h>.
+ */
+struct lock {
+	struct	simplelock lk_interlock; /* lock on remaining fields */
+	u_int	lk_flags;		/* see below */
+	int	lk_sharecount;		/* # of accepted shared locks */
+	int	lk_waitcount;		/* # of processes sleeping for lock */
+	short	lk_exclusivecount;	/* # of recursive exclusive locks */
+	short	lk_prio;		/* priority at which to sleep */
+	char	*lk_wmesg;		/* resource sleeping (for tsleep) */
+	int	lk_timo;		/* maximum sleep time (for tsleep) */
+	pid_t	lk_lockholder;		/* pid of exclusive lock holder */
+};
+/*
+ * Lock request types:
+ *   LK_SHARED - get one of many possible shared locks. If a process
+ *	holding an exclusive lock requests a shared lock, the exclusive
+ *	lock(s) will be downgraded to shared locks.
+ *   LK_EXCLUSIVE - stop further shared locks, when they are cleared,
+ *	grant a pending upgrade if it exists, then grant an exclusive
+ *	lock. Only one exclusive lock may exist at a time, except that
+ *	a process holding an exclusive lock may get additional exclusive
+ *	locks if it explicitly sets the LK_CANRECURSE flag in the lock
+ *	request, or if the LK_CANRECUSE flag was set when the lock was
+ *	initialized.
+ *   LK_UPGRADE - the process must hold a shared lock that it wants to
+ *	have upgraded to an exclusive lock. Other processes may get
+ *	exclusive access to the resource between the time that the upgrade
+ *	is requested and the time that it is granted.
+ *   LK_EXCLUPGRADE - the process must hold a shared lock that it wants to
+ *	have upgraded to an exclusive lock. If the request succeeds, no
+ *	other processes will have gotten exclusive access to the resource
+ *	between the time that the upgrade is requested and the time that
+ *	it is granted. However, if another process has already requested
+ *	an upgrade, the request will fail (see error returns below).
+ *   LK_DOWNGRADE - the process must hold an exclusive lock that it wants
+ *	to have downgraded to a shared lock. If the process holds multiple
+ *	(recursive) exclusive locks, they will all be downgraded to shared
+ *	locks.
+ *   LK_RELEASE - release one instance of a lock.
+ *   LK_DRAIN - wait for all activity on the lock to end, then mark it
+ *	decommissioned. This feature is used before freeing a lock that
+ *	is part of a piece of memory that is about to be freed.
+ *
+ * These are flags that are passed to the lockmgr routine.
+ */
+#define LK_TYPE_MASK	0x0000000f	/* type of lock sought */
+#define LK_SHARED	0x00000001	/* shared lock */
+#define LK_EXCLUSIVE	0x00000002	/* exclusive lock */
+#define LK_UPGRADE	0x00000003	/* shared-to-exclusive upgrade */
+#define LK_EXCLUPGRADE	0x00000004	/* first shared-to-exclusive upgrade */
+#define LK_DOWNGRADE	0x00000005	/* exclusive-to-shared downgrade */
+#define LK_RELEASE	0x00000006	/* release any type of lock */
+#define LK_DRAIN	0x00000007	/* wait for all lock activity to end */
+/*
+ * External lock flags.
+ *
+ * The first three flags may be set in lock_init to set their mode permanently,
+ * or passed in as arguments to the lock manager. The LK_REENABLE flag may be
+ * set only at the release of a lock obtained by drain.
+ */
+#define LK_EXTFLG_MASK	0x00000070	/* mask of external flags */
+#define LK_NOWAIT	0x00000010	/* do not sleep to await lock */
+#define LK_SLEEPFAIL	0x00000020	/* sleep, then return failure */
+#define LK_CANRECURSE	0x00000040	/* allow recursive exclusive lock */
+#define LK_REENABLE	0x00000080	/* lock is be reenabled after drain */
+/*
+ * Internal lock flags.
+ *
+ * These flags are used internally to the lock manager.
+ */
+#define LK_WANT_UPGRADE	0x00000100	/* waiting for share-to-excl upgrade */
+#define LK_WANT_EXCL	0x00000200	/* exclusive lock sought */
+#define LK_HAVE_EXCL	0x00000400	/* exclusive lock obtained */
+#define LK_WAITDRAIN	0x00000800	/* process waiting for lock to drain */
+#define LK_DRAINING	0x00004000	/* lock is being drained */
+#define LK_DRAINED	0x00008000	/* lock has been decommissioned */
+/*
+ * Control flags
+ *
+ * Non-persistent external flags.
+ */
+#define LK_INTERLOCK	0x00010000	/* unlock passed simple lock after
+					   getting lk_interlock */
+#define LK_RETRY	0x00020000	/* vn_lock: retry until locked */
+
+/*
+ * Lock return status.
+ *
+ * Successfully obtained locks return 0. Locks will always succeed
+ * unless one of the following is true:
+ *	LK_FORCEUPGRADE is requested and some other process has already
+ *	    requested a lock upgrade (returns EBUSY).
+ *	LK_WAIT is set and a sleep would be required (returns EBUSY).
+ *	LK_SLEEPFAIL is set and a sleep was done (returns ENOLCK).
+ *	PCATCH is set in lock priority and a signal arrives (returns
+ *	    either EINTR or ERESTART if system calls is to be restarted).
+ *	Non-null lock timeout and timeout expires (returns EWOULDBLOCK).
+ * A failed lock attempt always returns a non-zero error value. No lock
+ * is held after an error return (in particular, a failed LK_UPGRADE
+ * or LK_FORCEUPGRADE will have released its shared access lock).
+ */
+
+/*
+ * Indicator that no process holds exclusive lock
+ */
+#define LK_KERNPROC ((pid_t) -2)
+#define LK_NOPROC ((pid_t) -1)
+
+struct proc;
+
+void	lockinit __P((struct lock *, int prio, char *wmesg, int timo,
+			int flags));
+int	lockmgr __P((__volatile struct lock *, u_int flags,
+			struct simplelock *, struct proc *p));
+int	lockstatus __P((struct lock *));
+
+#ifdef DEBUG
+void _simple_unlock __P((__volatile struct simplelock *alp, const char *, int));
+#define simple_unlock(alp) _simple_unlock(alp, __FILE__, __LINE__)
+int _simple_lock_try __P((__volatile struct simplelock *alp, const char *, int));
+#define simple_lock_try(alp) _simple_lock_try(alp, __FILE__, __LINE__)
+void _simple_lock __P((__volatile struct simplelock *alp, const char *, int));
+#define simple_lock(alp) _simple_lock(alp, __FILE__, __LINE__)
+void simple_lock_init __P((struct simplelock *alp));
+#else /* !DEBUG */
+#if NCPUS == 1 /* no multiprocessor locking is necessary */
+#define	simple_lock_init(alp)
+#define	simple_lock(alp)
+#define	simple_lock_try(alp)	(1)	/* always succeeds */
+#define	simple_unlock(alp)
+#endif /* NCPUS == 1 */
+#endif /* !DEBUG */
+
+#endif /* !_LOCK_H_ */