bsd/sys/lock.h

   1 /*
   2  * Copyright (c) 2000-2002 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /* Copyright (c) 1995, 1997 Apple Computer, Inc. All Rights Reserved */
  26 /*
  27  * Copyright (c) 1995
  28  *      The Regents of the University of California.  All rights reserved.
  29  *
  30  * This code contains ideas from software contributed to Berkeley by
  31  * Avadis Tevanian, Jr., Michael Wayne Young, and the Mach Operating
  32  * System project at Carnegie-Mellon University.
  33  *
  34  * Redistribution and use in source and binary forms, with or without
  35  * modification, are permitted provided that the following conditions
  36  * are met:
  37  * 1. Redistributions of source code must retain the above copyright
  38  *    notice, this list of conditions and the following disclaimer.
  39  * 2. Redistributions in binary form must reproduce the above copyright
  40  *    notice, this list of conditions and the following disclaimer in the
  41  *    documentation and/or other materials provided with the distribution.
  42  * 3. All advertising materials mentioning features or use of this software
  43  *    must display the following acknowledgement:
  44  *      This product includes software developed by the University of
  45  *      California, Berkeley and its contributors.
  46  * 4. Neither the name of the University nor the names of its contributors
  47  *    may be used to endorse or promote products derived from this software
  48  *    without specific prior written permission.
  49  *
  50  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  51  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  52  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  53  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  54  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  55  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  56  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  57  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  58  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  59  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  60  * SUCH DAMAGE.
  61  *
  62  *      @(#)lock.h      8.12 (Berkeley) 5/19/95
  63  */
  64
  65 #ifndef _SYS_LOCK_H_
  66 #define _SYS_LOCK_H_
  67
  68 #include <sys/appleapiopts.h>
  69
  70 #ifdef KERNEL
  71 #ifdef __APPLE_API_UNSTABLE
  72 #include <kern/simple_lock.h>
  73 #include <kern/simple_lock_types.h>
  74
  75 #if defined(simple_lock_init)
  76 #undef simple_lock_init
  77 #endif
  78 #define simple_lock_init(l)     usimple_lock_init((l),0)
  79
  80 #if defined(simple_lock)
  81 #undef simple_lock
  82 #endif
  83 #define simple_lock(l)         ((void) 1)
  84
  85 #if defined(simple_unlock)
  86 #undef simple_unlock
  87 #endif
  88 #define simple_unlock(l)        ((void) 1)
  89
  90 #if defined(simple_lock_try)
  91 #undef simple_lock_try
  92 #endif
  93 #define simple_lock_try(l)      1
  94
  95 #if defined(thread_sleep_simple_lock)
  96 #undef thread_sleep_simple_lock
  97 #endif
  98 #define thread_sleep_simple_lock(l, e, i) thread_sleep_funnel((e), (i))
  99
 100 #endif /* __APPLE_API_UNSTABLE */
 101 #else /* KERNEL */
 102
 103 #ifndef _MACHINE_SIMPLE_LOCK_DATA_
 104 #define _MACHINE_SIMPLE_LOCK_DATA_
 105
 106 #include <mach/boolean.h>
 107
 108 #if defined(__ppc__)
 109 struct slock{
 110         volatile unsigned int lock_data[10];
 111 };
 112 #else
 113 struct slock{
 114         volatile unsigned int lock_data[9];
 115 };
 116 #endif
 117 typedef struct slock    simple_lock_data_t;
 118 typedef struct slock    *simple_lock_t;
 119 #define decl_simple_lock_data(class,name) \
 120 class   simple_lock_data_t      name;
 121
 122 #endif  /* _MACHINE_SIMPLE_LOCK_DATA_ */
 123
 124 #endif /* KERNEL */
 125
 126 #ifdef __APPLE_API_UNSTABLE
 127 /*
 128  * The general lock structure.  Provides for multiple shared locks,
 129  * upgrading from shared to exclusive, and sleeping until the lock
 130  * can be gained. The simple locks are defined in <machine/param.h>.
 131  */
 132 struct lock__bsd__ {
 133         simple_lock_data_t
 134                 lk_interlock;           /* lock on remaining fields */
 135         u_int   lk_flags;               /* see below */
 136         int     lk_sharecount;          /* # of accepted shared locks */
 137         int     lk_waitcount;           /* # of processes sleeping for lock */
 138         short   lk_exclusivecount;      /* # of recursive exclusive locks */
 139         short   lk_prio;                /* priority at which to sleep */
 140         char    *lk_wmesg;              /* resource sleeping (for tsleep) */
 141         int     lk_timo;                /* maximum sleep time (for tsleep) */
 142         pid_t   lk_lockholder;          /* pid of exclusive lock holder */
 143         void    *lk_lockthread;         /* thread which acquired excl lock */
 144 };
 145 /*
 146  * Lock request types:
 147  *   LK_SHARED - get one of many possible shared locks. If a process
 148  *      holding an exclusive lock requests a shared lock, the exclusive
 149  *      lock(s) will be downgraded to shared locks.
 150  *   LK_EXCLUSIVE - stop further shared locks, when they are cleared,
 151  *      grant a pending upgrade if it exists, then grant an exclusive
 152  *      lock. Only one exclusive lock may exist at a time, except that
 153  *      a process holding an exclusive lock may get additional exclusive
 154  *      locks if it explicitly sets the LK_CANRECURSE flag in the lock
 155  *      request, or if the LK_CANRECUSE flag was set when the lock was
 156  *      initialized.
 157  *   LK_UPGRADE - the process must hold a shared lock that it wants to
 158  *      have upgraded to an exclusive lock. Other processes may get
 159  *      exclusive access to the resource between the time that the upgrade
 160  *      is requested and the time that it is granted.
 161  *   LK_EXCLUPGRADE - the process must hold a shared lock that it wants to
 162  *      have upgraded to an exclusive lock. If the request succeeds, no
 163  *      other processes will have gotten exclusive access to the resource
 164  *      between the time that the upgrade is requested and the time that
 165  *      it is granted. However, if another process has already requested
 166  *      an upgrade, the request will fail (see error returns below).
 167  *   LK_DOWNGRADE - the process must hold an exclusive lock that it wants
 168  *      to have downgraded to a shared lock. If the process holds multiple
 169  *      (recursive) exclusive locks, they will all be downgraded to shared
 170  *      locks.
 171  *   LK_RELEASE - release one instance of a lock.
 172  *   LK_DRAIN - wait for all activity on the lock to end, then mark it
 173  *      decommissioned. This feature is used before freeing a lock that
 174  *      is part of a piece of memory that is about to be freed.
 175  *
 176  * These are flags that are passed to the lockmgr routine.
 177  */
 178 #define LK_TYPE_MASK    0x0000000f      /* type of lock sought */
 179 #define LK_SHARED       0x00000001      /* shared lock */
 180 #define LK_EXCLUSIVE    0x00000002      /* exclusive lock */
 181 #define LK_UPGRADE      0x00000003      /* shared-to-exclusive upgrade */
 182 #define LK_EXCLUPGRADE  0x00000004      /* first shared-to-exclusive upgrade */
 183 #define LK_DOWNGRADE    0x00000005      /* exclusive-to-shared downgrade */
 184 #define LK_RELEASE      0x00000006      /* release any type of lock */
 185 #define LK_DRAIN        0x00000007      /* wait for all lock activity to end */
 186 /*
 187  * External lock flags.
 188  *
 189  * The first three flags may be set in lock_init to set their mode permanently,
 190  * or passed in as arguments to the lock manager. The LK_REENABLE flag may be
 191  * set only at the release of a lock obtained by drain.
 192  */
 193 #define LK_EXTFLG_MASK  0x00000070      /* mask of external flags */
 194 #define LK_NOWAIT       0x00000010      /* do not sleep to await lock */
 195 #define LK_SLEEPFAIL    0x00000020      /* sleep, then return failure */
 196 #define LK_CANRECURSE   0x00000040      /* allow recursive exclusive lock */
 197 #define LK_REENABLE     0x00000080      /* lock is be reenabled after drain */
 198 /*
 199  * Internal lock flags.
 200  *
 201  * These flags are used internally to the lock manager.
 202  */
 203 #define LK_WANT_UPGRADE 0x00000100      /* waiting for share-to-excl upgrade */
 204 #define LK_WANT_EXCL    0x00000200      /* exclusive lock sought */
 205 #define LK_HAVE_EXCL    0x00000400      /* exclusive lock obtained */
 206 #define LK_WAITDRAIN    0x00000800      /* process waiting for lock to drain */
 207 #define LK_DRAINING     0x00004000      /* lock is being drained */
 208 #define LK_DRAINED      0x00008000      /* lock has been decommissioned */
 209 /*
 210  * Control flags
 211  *
 212  * Non-persistent external flags.
 213  */
 214 #define LK_INTERLOCK    0x00010000      /* unlock passed simple lock after
 215                                            getting lk_interlock */
 216 #define LK_RETRY        0x00020000      /* vn_lock: retry until locked */
 217
 218 /*
 219  * Lock return status.
 220  *
 221  * Successfully obtained locks return 0. Locks will always succeed
 222  * unless one of the following is true:
 223  *      LK_FORCEUPGRADE is requested and some other process has already
 224  *          requested a lock upgrade (returns EBUSY).
 225  *      LK_WAIT is set and a sleep would be required (returns EBUSY).
 226  *      LK_SLEEPFAIL is set and a sleep was done (returns ENOLCK).
 227  *      PCATCH is set in lock priority and a signal arrives (returns
 228  *          either EINTR or ERESTART if system calls is to be restarted).
 229  *      Non-null lock timeout and timeout expires (returns EWOULDBLOCK).
 230  * A failed lock attempt always returns a non-zero error value. No lock
 231  * is held after an error return (in particular, a failed LK_UPGRADE
 232  * or LK_FORCEUPGRADE will have released its shared access lock).
 233  */
 234
 235 /*
 236  * Indicator that no process holds exclusive lock
 237  */
 238 #define LK_KERNPROC ((pid_t) -2)
 239 #define LK_NOPROC ((pid_t) -1)
 240
 241 struct proc;
 242
 243 void    lockinit __P((struct lock__bsd__ *, int prio, char *wmesg, int timo,
 244                         int flags));
 245 int     lockmgr __P((struct lock__bsd__ *, u_int flags,
 246                         simple_lock_t, struct proc *p));
 247 int     lockstatus __P((struct lock__bsd__ *));
 248
 249 #endif /* __APPLE_API_UNSTABLE */
 250
 251 #endif  /* _SYS_LOCK_H_ */