bsd/sys/lock.h

   1 /*
   2  * Copyright (c) 2000-2005 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /* Copyright (c) 1995, 1997 Apple Computer, Inc. All Rights Reserved */
  23 /*
  24  * Copyright (c) 1995
  25  *      The Regents of the University of California.  All rights reserved.
  26  *
  27  * This code contains ideas from software contributed to Berkeley by
  28  * Avadis Tevanian, Jr., Michael Wayne Young, and the Mach Operating
  29  * System project at Carnegie-Mellon University.
  30  *
  31  * Redistribution and use in source and binary forms, with or without
  32  * modification, are permitted provided that the following conditions
  33  * are met:
  34  * 1. Redistributions of source code must retain the above copyright
  35  *    notice, this list of conditions and the following disclaimer.
  36  * 2. Redistributions in binary form must reproduce the above copyright
  37  *    notice, this list of conditions and the following disclaimer in the
  38  *    documentation and/or other materials provided with the distribution.
  39  * 3. All advertising materials mentioning features or use of this software
  40  *    must display the following acknowledgement:
  41  *      This product includes software developed by the University of
  42  *      California, Berkeley and its contributors.
  43  * 4. Neither the name of the University nor the names of its contributors
  44  *    may be used to endorse or promote products derived from this software
  45  *    without specific prior written permission.
  46  *
  47  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  48  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  49  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  50  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  51  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  52  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  53  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  54  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  55  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  56  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  57  * SUCH DAMAGE.
  58  *
  59  *      @(#)lock.h      8.12 (Berkeley) 5/19/95
  60  */
  61
  62 #ifndef _SYS_LOCK_H_
  63 #define _SYS_LOCK_H_
  64
  65 #include <sys/appleapiopts.h>
  66 #include <sys/types.h>
  67 #include <sys/cdefs.h>
  68
  69 #ifdef KERNEL
  70
  71 #include <kern/locks.h>
  72
  73
  74 #if defined(thread_sleep_simple_lock)
  75 #undef thread_sleep_simple_lock
  76 #endif
  77 #define thread_sleep_simple_lock(l, e, i) thread_sleep_funnel((e), (i))
  78
  79
  80 #endif /* KERNEL */
  81
  82 #ifdef BSD_KERNEL_PRIVATE
  83 /*
  84  * The general lock structure.  Provides for multiple shared locks,
  85  * upgrading from shared to exclusive, and sleeping until the lock
  86  * can be gained. The simple locks are defined in <machine/param.h>.
  87  */
  88 struct lock__bsd__ {
  89         void * lk_interlock[10];                /* lock on remaining fields */
  90         u_int   lk_flags;               /* see below */
  91         int     lk_sharecount;          /* # of accepted shared locks */
  92         int     lk_waitcount;           /* # of processes sleeping for lock */
  93         short   lk_exclusivecount;      /* # of recursive exclusive locks */
  94         short   lk_prio;                /* priority at which to sleep */
  95         const char      *lk_wmesg;      /* resource sleeping (for tsleep) */
  96         int     lk_timo;                /* maximum sleep time (for tsleep) */
  97         pid_t   lk_lockholder;          /* pid of exclusive lock holder */
  98         void    *lk_lockthread;         /* thread which acquired excl lock */
  99 };
 100
 101 // LP64todo - should this move?
 102
 103 /* LP64 version of lock__bsd__.  all pointers
 104  * grow when we're dealing with a 64-bit process.
 105  * WARNING - keep in sync with lock__bsd__
 106  */
 107
 108 #if __DARWIN_ALIGN_NATURAL
 109 #pragma options align=natural
 110 #endif
 111
 112 struct user_lock__bsd__ {
 113         user_addr_t     lk_interlock[10];   /* lock on remaining fields */
 114         u_int           lk_flags;                       /* see below */
 115         int                     lk_sharecount;          /* # of accepted shared locks */
 116         int                     lk_waitcount;           /* # of processes sleeping for lock */
 117         short           lk_exclusivecount;      /* # of recursive exclusive locks */
 118         short           lk_prio;                        /* priority at which to sleep */
 119         user_addr_t lk_wmesg;           /* resource sleeping (for tsleep) */
 120         int                     lk_timo;                        /* maximum sleep time (for tsleep) */
 121         pid_t           lk_lockholder;          /* pid of exclusive lock holder */
 122         user_addr_t     lk_lockthread;          /* thread which acquired excl lock */
 123 };
 124
 125 #if __DARWIN_ALIGN_NATURAL
 126 #pragma options align=reset
 127 #endif
 128
 129 /*
 130  * Lock request types:
 131  *   LK_SHARED - get one of many possible shared locks. If a process
 132  *      holding an exclusive lock requests a shared lock, the exclusive
 133  *      lock(s) will be downgraded to shared locks.
 134  *   LK_EXCLUSIVE - stop further shared locks, when they are cleared,
 135  *      grant a pending upgrade if it exists, then grant an exclusive
 136  *      lock. Only one exclusive lock may exist at a time, except that
 137  *      a process holding an exclusive lock may get additional exclusive
 138  *      locks if it explicitly sets the LK_CANRECURSE flag in the lock
 139  *      request, or if the LK_CANRECUSE flag was set when the lock was
 140  *      initialized.
 141  *   LK_UPGRADE - the process must hold a shared lock that it wants to
 142  *      have upgraded to an exclusive lock. Other processes may get
 143  *      exclusive access to the resource between the time that the upgrade
 144  *      is requested and the time that it is granted.
 145  *   LK_EXCLUPGRADE - the process must hold a shared lock that it wants to
 146  *      have upgraded to an exclusive lock. If the request succeeds, no
 147  *      other processes will have gotten exclusive access to the resource
 148  *      between the time that the upgrade is requested and the time that
 149  *      it is granted. However, if another process has already requested
 150  *      an upgrade, the request will fail (see error returns below).
 151  *   LK_DOWNGRADE - the process must hold an exclusive lock that it wants
 152  *      to have downgraded to a shared lock. If the process holds multiple
 153  *      (recursive) exclusive locks, they will all be downgraded to shared
 154  *      locks.
 155  *   LK_RELEASE - release one instance of a lock.
 156  *   LK_DRAIN - wait for all activity on the lock to end, then mark it
 157  *      decommissioned. This feature is used before freeing a lock that
 158  *      is part of a piece of memory that is about to be freed.
 159  *
 160  * These are flags that are passed to the lockmgr routine.
 161  */
 162 #define LK_TYPE_MASK    0x0000000f      /* type of lock sought */
 163 #define LK_SHARED       0x00000001      /* shared lock */
 164 #define LK_EXCLUSIVE    0x00000002      /* exclusive lock */
 165 #define LK_UPGRADE      0x00000003      /* shared-to-exclusive upgrade */
 166 #define LK_EXCLUPGRADE  0x00000004      /* first shared-to-exclusive upgrade */
 167 #define LK_DOWNGRADE    0x00000005      /* exclusive-to-shared downgrade */
 168 #define LK_RELEASE      0x00000006      /* release any type of lock */
 169 #define LK_DRAIN        0x00000007      /* wait for all lock activity to end */
 170 /*
 171  * External lock flags.
 172  *
 173  * The first three flags may be set in lock_init to set their mode permanently,
 174  * or passed in as arguments to the lock manager. The LK_REENABLE flag may be
 175  * set only at the release of a lock obtained by drain.
 176  */
 177 #define LK_EXTFLG_MASK  0x00000070      /* mask of external flags */
 178 #define LK_NOWAIT       0x00000010      /* do not sleep to await lock */
 179 #define LK_SLEEPFAIL    0x00000020      /* sleep, then return failure */
 180 #define LK_CANRECURSE   0x00000040      /* allow recursive exclusive lock */
 181 #define LK_REENABLE     0x00000080      /* lock is be reenabled after drain */
 182 /*
 183  * Internal lock flags.
 184  *
 185  * These flags are used internally to the lock manager.
 186  */
 187 #define LK_WANT_UPGRADE 0x00000100      /* waiting for share-to-excl upgrade */
 188 #define LK_WANT_EXCL    0x00000200      /* exclusive lock sought */
 189 #define LK_HAVE_EXCL    0x00000400      /* exclusive lock obtained */
 190 #define LK_WAITDRAIN    0x00000800      /* process waiting for lock to drain */
 191 #define LK_DRAINING     0x00004000      /* lock is being drained */
 192 #define LK_DRAINED      0x00008000      /* lock has been decommissioned */
 193 /*
 194  * Control flags
 195  *
 196  * Non-persistent external flags.
 197  */
 198 #define LK_INTERLOCK    0x00010000      /* unlock passed simple lock after
 199                                            getting lk_interlock */
 200 #define LK_RETRY        0x00020000      /* vn_lock: retry until locked */
 201
 202 /*
 203  * Lock return status.
 204  *
 205  * Successfully obtained locks return 0. Locks will always succeed
 206  * unless one of the following is true:
 207  *      LK_FORCEUPGRADE is requested and some other process has already
 208  *          requested a lock upgrade (returns EBUSY).
 209  *      LK_WAIT is set and a sleep would be required (returns EBUSY).
 210  *      LK_SLEEPFAIL is set and a sleep was done (returns ENOLCK).
 211  *      PCATCH is set in lock priority and a signal arrives (returns
 212  *          either EINTR or ERESTART if system calls is to be restarted).
 213  *      Non-null lock timeout and timeout expires (returns EWOULDBLOCK).
 214  * A failed lock attempt always returns a non-zero error value. No lock
 215  * is held after an error return (in particular, a failed LK_UPGRADE
 216  * or LK_FORCEUPGRADE will have released its shared access lock).
 217  */
 218
 219 /*
 220  * Indicator that no process holds exclusive lock
 221  */
 222 #define LK_KERNPROC ((pid_t) -2)
 223 #define LK_NOPROC ((pid_t) -1)
 224
 225 struct proc;
 226
 227 void    lockinit(struct lock__bsd__ *, int prio, const char *wmesg, int timo,
 228                         int flags);
 229 int     lockmgr(struct lock__bsd__ *, u_int flags,
 230                         void *, struct proc *p);
 231 int     lockstatus(struct lock__bsd__ *);
 232
 233 #endif /* BSD_KERNEL_PRIVATE  */
 234
 235 #endif  /* _SYS_LOCK_H_ */