/*- * 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. * 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 * $FreeBSD$ */ #ifndef _SYS_LOCKMGR_H_ #define _SYS_LOCKMGR_H_ #ifdef DEBUG_LOCKS #include /* XXX */ #endif #include #include struct mtx; /* * The general lock structure. Provides for multiple shared locks, * upgrading from shared to exclusive, and sleeping until the lock * can be gained. */ struct lock { struct lock_object lk_object; /* common lock properties */ struct mtx *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 */ int lk_timo; /* maximum sleep time (for tsleep) */ struct thread *lk_lockholder; /* thread of exclusive lock holder */ struct lock *lk_newlock; /* lock taking over this lock */ #ifdef DEBUG_LOCKS struct stack lk_stack; #endif }; #define lk_wmesg lk_object.lo_name /* * 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. * LK_EXCLOTHER - return for lockstatus(). Used when another process * holds the lock exclusively. * * 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 */ #define LK_EXCLOTHER 0x00000008 /* other process holds lock */ /* * External lock flags. * * These may be set in lock_init to set their mode permanently, * or passed in as arguments to the lock manager. */ #define LK_EXTFLG_MASK 0x00000ff0 /* 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_NOSHARE 0x00000080 /* Only allow exclusive locks */ #define LK_TIMELOCK 0x00000100 /* use lk_timo, else no timeout */ /* * Nonpersistent external flags. */ #define LK_RETRY 0x00001000 /* vn_lock: retry until locked */ #define LK_INTERLOCK 0x00002000 /* * unlock passed mutex after getting * lk_interlock */ /* * Internal lock flags. * * These flags are used internally to the lock manager. */ #define LK_WANT_UPGRADE 0x00010000 /* waiting for share-to-excl upgrade */ #define LK_WANT_EXCL 0x00020000 /* exclusive lock sought */ #define LK_HAVE_EXCL 0x00040000 /* exclusive lock obtained */ #define LK_WAITDRAIN 0x00080000 /* process waiting for lock to drain */ #define LK_DRAINING 0x00100000 /* lock is being drained */ #define LK_INTERNAL 0x00200000/* The internal lock is already held */ /* * Internal state flags corresponding to lk_sharecount, and lk_waitcount */ #define LK_SHARE_NONZERO 0x01000000 #define LK_WAIT_NONZERO 0x02000000 /* * 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 ((struct thread *)-2) #define LK_NOPROC ((struct thread *) -1) #ifdef _KERNEL #if !defined(LOCK_FILE) || !defined(LOCK_LINE) #error "LOCK_FILE and LOCK_LINE not defined, include before" #endif #ifdef INVARIANTS #define LOCKMGR_ASSERT(lkp, what, p) do { \ switch ((what)) { \ case LK_SHARED: \ if (lockstatus((lkp), (p)) == LK_SHARED) \ break; \ /* fall into exclusive */ \ case LK_EXCLUSIVE: \ if (lockstatus((lkp), (p)) != LK_EXCLUSIVE) \ panic("lock %s %s not held at %s:%d", \ (lkp)->lk_wmesg, #what, LOCK_FILE, \ LOCK_LINE); \ break; \ default: \ panic("unknown LOCKMGR_ASSERT at %s:%d", LOCK_FILE, \ LOCK_LINE); \ } \ } while (0) #else /* INVARIANTS */ #define LOCKMGR_ASSERT(lkp, p, what) #endif /* INVARIANTS */ struct thread; void lockinit(struct lock *, int prio, const char *wmesg, int timo, int flags); void lockdestroy(struct lock *); int _lockmgr(struct lock *, u_int flags, struct mtx *, struct thread *p, char *file, int line); void transferlockers(struct lock *, struct lock *); void lockmgr_printinfo(struct lock *); int lockstatus(struct lock *, struct thread *); int lockcount(struct lock *); int lockwaiters(struct lock *); #define lockmgr(lock, flags, mtx, td) \ _lockmgr((lock), (flags), (mtx), (td), LOCK_FILE, LOCK_LINE) #ifdef DDB int lockmgr_chain(struct thread *td, struct thread **ownerp); #endif #endif /* !_KERNEL */ #endif /* !_SYS_LOCKMGR_H_ */