bsd/sys/lock.h

   1 /*
   2  * Copyright (c) 2006 Apple Computer, Inc. All Rights Reserved.
   3  *
   4  * @APPLE_LICENSE_OSREFERENCE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License.  The rights granted to you under the
  10  * License may not be used to create, or enable the creation or
  11  * redistribution of, unlawful or unlicensed copies of an Apple operating
  12  * system, or to circumvent, violate, or enable the circumvention or
  13  * violation of, any terms of an Apple operating system software license
  14  * agreement.
  15  *
  16  * Please obtain a copy of the License at
  17  * http://www.opensource.apple.com/apsl/ and read it before using this
  18  * file.
  19  *
  20  * The Original Code and all software distributed under the License are
  21  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  22  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  23  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  24  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  25  * Please see the License for the specific language governing rights and
  26  * limitations under the License.
  27  *
  28  * @APPLE_LICENSE_OSREFERENCE_HEADER_END@
  29  */
  30 /* Copyright (c) 1995, 1997 Apple Computer, Inc. All Rights Reserved */
  31 /*
  32  * Copyright (c) 1995
  33  *      The Regents of the University of California.  All rights reserved.
  34  *
  35  * This code contains ideas from software contributed to Berkeley by
  36  * Avadis Tevanian, Jr., Michael Wayne Young, and the Mach Operating
  37  * System project at Carnegie-Mellon University.
  38  *
  39  * Redistribution and use in source and binary forms, with or without
  40  * modification, are permitted provided that the following conditions
  41  * are met:
  42  * 1. Redistributions of source code must retain the above copyright
  43  *    notice, this list of conditions and the following disclaimer.
  44  * 2. Redistributions in binary form must reproduce the above copyright
  45  *    notice, this list of conditions and the following disclaimer in the
  46  *    documentation and/or other materials provided with the distribution.
  47  * 3. All advertising materials mentioning features or use of this software
  48  *    must display the following acknowledgement:
  49  *      This product includes software developed by the University of
  50  *      California, Berkeley and its contributors.
  51  * 4. Neither the name of the University nor the names of its contributors
  52  *    may be used to endorse or promote products derived from this software
  53  *    without specific prior written permission.
  54  *
  55  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  56  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  57  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  58  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  59  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  60  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  61  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  62  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  63  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  64  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  65  * SUCH DAMAGE.
  66  *
  67  *      @(#)lock.h      8.12 (Berkeley) 5/19/95
  68  */
  69
  70 #ifndef _SYS_LOCK_H_
  71 #define _SYS_LOCK_H_
  72
  73 #include <sys/appleapiopts.h>
  74 #include <sys/types.h>
  75 #include <sys/cdefs.h>
  76
  77 #ifdef KERNEL
  78
  79 #include <kern/locks.h>
  80
  81
  82 #if defined(thread_sleep_simple_lock)
  83 #undef thread_sleep_simple_lock
  84 #endif
  85 #define thread_sleep_simple_lock(l, e, i) thread_sleep_funnel((e), (i))
  86
  87
  88 #endif /* KERNEL */
  89
  90 #ifdef BSD_KERNEL_PRIVATE
  91 /*
  92  * The general lock structure.  Provides for multiple shared locks,
  93  * upgrading from shared to exclusive, and sleeping until the lock
  94  * can be gained. The simple locks are defined in <machine/param.h>.
  95  */
  96 struct lock__bsd__ {
  97         void * lk_interlock[10];                /* lock on remaining fields */
  98         u_int   lk_flags;               /* see below */
  99         int     lk_sharecount;          /* # of accepted shared locks */
 100         int     lk_waitcount;           /* # of processes sleeping for lock */
 101         short   lk_exclusivecount;      /* # of recursive exclusive locks */
 102         short   lk_prio;                /* priority at which to sleep */
 103         const char      *lk_wmesg;      /* resource sleeping (for tsleep) */
 104         int     lk_timo;                /* maximum sleep time (for tsleep) */
 105         pid_t   lk_lockholder;          /* pid of exclusive lock holder */
 106         void    *lk_lockthread;         /* thread which acquired excl lock */
 107 };
 108
 109 // LP64todo - should this move?
 110
 111 /* LP64 version of lock__bsd__.  all pointers
 112  * grow when we're dealing with a 64-bit process.
 113  * WARNING - keep in sync with lock__bsd__
 114  */
 115
 116 #if __DARWIN_ALIGN_NATURAL
 117 #pragma options align=natural
 118 #endif
 119
 120 struct user_lock__bsd__ {
 121         user_addr_t     lk_interlock[10];   /* lock on remaining fields */
 122         u_int           lk_flags;                       /* see below */
 123         int                     lk_sharecount;          /* # of accepted shared locks */
 124         int                     lk_waitcount;           /* # of processes sleeping for lock */
 125         short           lk_exclusivecount;      /* # of recursive exclusive locks */
 126         short           lk_prio;                        /* priority at which to sleep */
 127         user_addr_t lk_wmesg;           /* resource sleeping (for tsleep) */
 128         int                     lk_timo;                        /* maximum sleep time (for tsleep) */
 129         pid_t           lk_lockholder;          /* pid of exclusive lock holder */
 130         user_addr_t     lk_lockthread;          /* thread which acquired excl lock */
 131 };
 132
 133 #if __DARWIN_ALIGN_NATURAL
 134 #pragma options align=reset
 135 #endif
 136
 137 /*
 138  * Lock request types:
 139  *   LK_SHARED - get one of many possible shared locks. If a process
 140  *      holding an exclusive lock requests a shared lock, the exclusive
 141  *      lock(s) will be downgraded to shared locks.
 142  *   LK_EXCLUSIVE - stop further shared locks, when they are cleared,
 143  *      grant a pending upgrade if it exists, then grant an exclusive
 144  *      lock. Only one exclusive lock may exist at a time, except that
 145  *      a process holding an exclusive lock may get additional exclusive
 146  *      locks if it explicitly sets the LK_CANRECURSE flag in the lock
 147  *      request, or if the LK_CANRECUSE flag was set when the lock was
 148  *      initialized.
 149  *   LK_UPGRADE - the process must hold a shared lock that it wants to
 150  *      have upgraded to an exclusive lock. Other processes may get
 151  *      exclusive access to the resource between the time that the upgrade
 152  *      is requested and the time that it is granted.
 153  *   LK_EXCLUPGRADE - the process must hold a shared lock that it wants to
 154  *      have upgraded to an exclusive lock. If the request succeeds, no
 155  *      other processes will have gotten exclusive access to the resource
 156  *      between the time that the upgrade is requested and the time that
 157  *      it is granted. However, if another process has already requested
 158  *      an upgrade, the request will fail (see error returns below).
 159  *   LK_DOWNGRADE - the process must hold an exclusive lock that it wants
 160  *      to have downgraded to a shared lock. If the process holds multiple
 161  *      (recursive) exclusive locks, they will all be downgraded to shared
 162  *      locks.
 163  *   LK_RELEASE - release one instance of a lock.
 164  *   LK_DRAIN - wait for all activity on the lock to end, then mark it
 165  *      decommissioned. This feature is used before freeing a lock that
 166  *      is part of a piece of memory that is about to be freed.
 167  *
 168  * These are flags that are passed to the lockmgr routine.
 169  */
 170 #define LK_TYPE_MASK    0x0000000f      /* type of lock sought */
 171 #define LK_SHARED       0x00000001      /* shared lock */
 172 #define LK_EXCLUSIVE    0x00000002      /* exclusive lock */
 173 #define LK_UPGRADE      0x00000003      /* shared-to-exclusive upgrade */
 174 #define LK_EXCLUPGRADE  0x00000004      /* first shared-to-exclusive upgrade */
 175 #define LK_DOWNGRADE    0x00000005      /* exclusive-to-shared downgrade */
 176 #define LK_RELEASE      0x00000006      /* release any type of lock */
 177 #define LK_DRAIN        0x00000007      /* wait for all lock activity to end */
 178 /*
 179  * External lock flags.
 180  *
 181  * The first three flags may be set in lock_init to set their mode permanently,
 182  * or passed in as arguments to the lock manager. The LK_REENABLE flag may be
 183  * set only at the release of a lock obtained by drain.
 184  */
 185 #define LK_EXTFLG_MASK  0x00000070      /* mask of external flags */
 186 #define LK_NOWAIT       0x00000010      /* do not sleep to await lock */
 187 #define LK_SLEEPFAIL    0x00000020      /* sleep, then return failure */
 188 #define LK_CANRECURSE   0x00000040      /* allow recursive exclusive lock */
 189 #define LK_REENABLE     0x00000080      /* lock is be reenabled after drain */
 190 /*
 191  * Internal lock flags.
 192  *
 193  * These flags are used internally to the lock manager.
 194  */
 195 #define LK_WANT_UPGRADE 0x00000100      /* waiting for share-to-excl upgrade */
 196 #define LK_WANT_EXCL    0x00000200      /* exclusive lock sought */
 197 #define LK_HAVE_EXCL    0x00000400      /* exclusive lock obtained */
 198 #define LK_WAITDRAIN    0x00000800      /* process waiting for lock to drain */
 199 #define LK_DRAINING     0x00004000      /* lock is being drained */
 200 #define LK_DRAINED      0x00008000      /* lock has been decommissioned */
 201 /*
 202  * Control flags
 203  *
 204  * Non-persistent external flags.
 205  */
 206 #define LK_INTERLOCK    0x00010000      /* unlock passed simple lock after
 207                                            getting lk_interlock */
 208 #define LK_RETRY        0x00020000      /* vn_lock: retry until locked */
 209
 210 /*
 211  * Lock return status.
 212  *
 213  * Successfully obtained locks return 0. Locks will always succeed
 214  * unless one of the following is true:
 215  *      LK_FORCEUPGRADE is requested and some other process has already
 216  *          requested a lock upgrade (returns EBUSY).
 217  *      LK_WAIT is set and a sleep would be required (returns EBUSY).
 218  *      LK_SLEEPFAIL is set and a sleep was done (returns ENOLCK).
 219  *      PCATCH is set in lock priority and a signal arrives (returns
 220  *          either EINTR or ERESTART if system calls is to be restarted).
 221  *      Non-null lock timeout and timeout expires (returns EWOULDBLOCK).
 222  * A failed lock attempt always returns a non-zero error value. No lock
 223  * is held after an error return (in particular, a failed LK_UPGRADE
 224  * or LK_FORCEUPGRADE will have released its shared access lock).
 225  */
 226
 227 /*
 228  * Indicator that no process holds exclusive lock
 229  */
 230 #define LK_KERNPROC ((pid_t) -2)
 231 #define LK_NOPROC ((pid_t) -1)
 232
 233 struct proc;
 234
 235 void    lockinit(struct lock__bsd__ *, int prio, const char *wmesg, int timo,
 236                         int flags);
 237 int     lockmgr(struct lock__bsd__ *, u_int flags,
 238                         void *, struct proc *p);
 239 int     lockstatus(struct lock__bsd__ *);
 240
 241 #endif /* BSD_KERNEL_PRIVATE  */
 242
 243 #endif  /* _SYS_LOCK_H_ */