FreeBSD/Linux Kernel Cross Reference
sys/sys/lock.h

     /*      $NetBSD: lock.h,v 1.66.6.1 2007/08/01 14:45:45 liamjfoy Exp $   */
     
     /*-
      * Copyright (c) 1999, 2000 The NetBSD Foundation, Inc.
      * All rights reserved.
      *
      * This code is derived from software contributed to The NetBSD Foundation
      * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
      * NASA Ames Research Center.
     *
     * This code is derived from software contributed to The NetBSD Foundation
     * by Ross Harvey.
     *
     * 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 NetBSD
     *      Foundation, Inc. and its contributors.
     * 4. Neither the name of The NetBSD Foundation 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
     */
    
    /*
     * 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. 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 _SYS_LOCK_H_
    #define _SYS_LOCK_H_
    
    #if defined(_KERNEL_OPT)
    #include "opt_lockdebug.h"
    #include "opt_multiprocessor.h"
    #endif
    
    #include <sys/queue.h>
    #include <machine/lock.h>
    
    /*
     * The simple lock.  Provides a simple spinning mutex.  Note the
     * member which is used in atomic operations must be aligned in
     * order for it to work on the widest range of processor types.
     */
    struct simplelock {
            __cpu_simple_lock_t lock_data;
    #ifdef LOCKDEBUG
            const char *lock_file;
            const char *unlock_file;
            short lock_line;
           short unlock_line;
           _TAILQ_ENTRY(struct simplelock, volatile) list;
           cpuid_t lock_holder;            /* CPU ID */
   #endif
   };
   
   #ifdef LOCKDEBUG
   #define SIMPLELOCK_INITIALIZER  { __SIMPLELOCK_UNLOCKED, NULL, NULL, 0, \
                                     0, { NULL, NULL }, LK_NOCPU }
   #else
   #define SIMPLELOCK_INITIALIZER  { __SIMPLELOCK_UNLOCKED }
   #endif
   
   /*
    * The general lock structure.  Provides for multiple shared locks,
    * upgrading from shared to exclusive, and sleeping/spinning until the
    * lock can be gained.
    */
   struct lock {
           struct  simplelock lk_interlock; /* lock on remaining fields */
           u_int   lk_flags;               /* see below */
           int     lk_sharecount;          /* # of accepted shared locks */
           short   lk_exclusivecount;      /* # of recursive exclusive locks */
           short   lk_recurselevel;        /* lvl above which recursion ok */
           int     lk_waitcount;           /* # of sleepers/spinners */
   
           /*
            * This is the sleep message for sleep locks, and a simple name
            * for spin locks.
            */
           const char *lk_wmesg;
   
           union {
                   struct {
                           /* pid of exclusive lock holder */
                           pid_t lk_sleep_lockholder;
                           lwpid_t lk_sleep_locklwp;
   
                           /* priority at which to sleep */
                           int lk_sleep_prio;
   
                           /* maximum sleep time (for tsleep) */
                           int lk_sleep_timo;
   
                           /* lock taking over this lock */
                           struct lock *lk_newlock;
                   } lk_un_sleep;
                   struct {
                           /* CPU ID of exclusive lock holder */
                           cpuid_t lk_spin_cpu;
   #if defined(LOCKDEBUG)
                           _TAILQ_ENTRY(struct lock, volatile) lk_spin_list;
   #endif
                   } lk_un_spin;
           } lk_un;
   
   #define lk_lockholder   lk_un.lk_un_sleep.lk_sleep_lockholder
   #define lk_locklwp      lk_un.lk_un_sleep.lk_sleep_locklwp
   #define lk_prio         lk_un.lk_un_sleep.lk_sleep_prio
   #define lk_timo         lk_un.lk_un_sleep.lk_sleep_timo
   #define lk_newlock      lk_un.lk_un_sleep.lk_newlock
   
   #define lk_cpu          lk_un.lk_un_spin.lk_spin_cpu
   #if defined(LOCKDEBUG)
   #define lk_list         lk_un.lk_un_spin.lk_spin_list
   #endif
   
   #if defined(LOCKDEBUG)
           const char *lk_lock_file;
           const char *lk_unlock_file;
           int lk_lock_line;
           int lk_unlock_line;
   #endif
   };
   
   #ifndef LOCKDEBUG
   #define LOCK_INITIALIZER(prio, wmesg, timo, flags)                      \
           { SIMPLELOCK_INITIALIZER,       /* interlock */                 \
             (flags),                      /* flags */                     \
             0,                            /* sharecount */                \
             0,                            /* exclusivecount */            \
             0,                            /* recurselevel */              \
             0,                            /* waitcount */                 \
             (wmesg),                      /* waitmesg */                  \
             { .lk_un_sleep = { 0, 0, (prio), (timo), NULL } },            \
           }
   #else
   #define LOCK_INITIALIZER(prio, wmesg, timo, flags)                      \
           { SIMPLELOCK_INITIALIZER,       /* interlock */                 \
             (flags),                      /* flags */                     \
             0,                            /* sharecount */                \
             0,                            /* exclusivecount */            \
             0,                            /* recurselevel */              \
             0,                            /* waitcount */                 \
             (wmesg),                      /* waitmesg */                  \
             { .lk_un_sleep = { 0, 0, (prio), (timo), NULL } },            \
             NULL,                         /* lk_lock_file */              \
             NULL,                         /* lk_unlock_file */            \
             0,                            /* lk_lock_line */              \
             0,                            /* lk_unlock_line */            \
           }
   #endif
   
   
   
   /*
    * 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_CANRECURSE 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 */
   #define LK_EXCLOTHER    0x00000008      /* other process holds lock */
   /*
    * 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  0x00f00070      /* 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      /* this may be recursive lock attempt */
   #define LK_REENABLE     0x00000080      /* lock is be reenabled after drain */
   #define LK_SETRECURSE   0x00100000      /* other locks while we have it OK */
   #define LK_RECURSEFAIL  0x00200000      /* attempt at recursive lock fails */
   #define LK_SPIN         0x00400000      /* lock spins instead of sleeps */
   #define LK_RESURRECT    0x00800000      /* immediately reenable drained lock */
   /*
    * 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 */
   /*
    * Internal state flags corresponding to lk_sharecount, and lk_waitcount
    */
   #define LK_SHARE_NONZERO 0x00040000     /* lk_sharecount != 0 */
   #define LK_WAIT_NONZERO 0x00080000      /* lk_waitcount != 0 */
   /*
    * 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_NOWAIT 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/cpu holds exclusive lock
    */
   #define LK_KERNPROC     ((pid_t) -2)
   #define LK_NOPROC       ((pid_t) -1)
   #define LK_NOCPU        ((cpuid_t) -1)
   
   #ifdef _KERNEL
   
   struct proc;
   
   void    lockinit(struct lock *, int, const char *, int, int);
   #if defined(LOCKDEBUG)
   int     _lockmgr(volatile struct lock *, u_int, struct simplelock *,
               const char *, int);
   #define lockmgr(l, f, i)        _lockmgr((l), (f), (i), __FILE__, __LINE__)
   #else
   int     lockmgr(volatile struct lock *, u_int flags, struct simplelock *);
   #endif /* LOCKDEBUG */
   void    transferlockers(struct lock *, struct lock *);
   int     lockstatus(struct lock *);
   void    lockmgr_printinfo(volatile struct lock *);
   
   #if defined(LOCKDEBUG)
   void    spinlock_switchcheck(void);
   #endif
   
   #if defined(MULTIPROCESSOR) || defined(LOCKDEBUG)
   #define spinlockinit(lkp, name, flags)                                  \
           lockinit((lkp), 0, (name), 0, (flags) | LK_SPIN)
   #define spinlockmgr(lkp, flags, intrlk)                                 \
           lockmgr((lkp), (flags) | LK_SPIN, (intrlk))
   #else
   #define spinlockinit(lkp, name, flags)          (void)(lkp)
   #define spinlockmgr(lkp, flags, intrlk)         (0)
   #endif
   
   #if defined(LOCKDEBUG)
   int     _spinlock_release_all(volatile struct lock *, const char *, int);
   void    _spinlock_acquire_count(volatile struct lock *, int, const char *,
               int);
   
   #define spinlock_release_all(l) _spinlock_release_all((l), __FILE__, __LINE__)
   #define spinlock_acquire_count(l, c) _spinlock_acquire_count((l), (c),  \
                                           __FILE__, __LINE__)
   
   #else
   int     spinlock_release_all(volatile struct lock *);
   void    spinlock_acquire_count(volatile struct lock *, int);
   #endif
   
   #if defined(LOCKDEBUG)
   
   void _simple_lock(volatile struct simplelock *, const char *, int);
   int  _simple_lock_try(volatile struct simplelock *, const char *, int);
   void _simple_unlock(volatile struct simplelock *, const char *, int);
   int  _simple_lock_held(volatile struct simplelock *);
   void simple_lock_only_held(volatile struct simplelock *, const char *);
   void _simple_lock_assert_locked(volatile struct simplelock *, const char *,
       const char *, int l);
   void _simple_lock_assert_unlocked(volatile struct simplelock *, const char *,
       const char *, int l);
   
   #define simple_lock(alp)        _simple_lock((alp), __FILE__, __LINE__)
   #define simple_lock_try(alp)    _simple_lock_try((alp), __FILE__, __LINE__)
   #define simple_unlock(alp)      _simple_unlock((alp), __FILE__, __LINE__)
   #define simple_lock_held(alp)   _simple_lock_held((alp))
   #define simple_lock_assert_locked(alp,lockname) \
           _simple_lock_assert_locked((alp),(lockname), __FILE__, __LINE__)
   #define simple_lock_assert_unlocked(alp,lockname) \
           _simple_lock_assert_unlocked((alp),(lockname), __FILE__, __LINE__)
   
   #define LOCK_ASSERT(x)          KASSERT(x)
   
   void    simple_lock_init(volatile struct simplelock *);
   void    simple_lock_dump(void);
   void    simple_lock_freecheck(void *, void *);
   void    simple_lock_switchcheck(void);
   #elif defined(MULTIPROCESSOR)
   #define simple_lock_init(alp)   __cpu_simple_lock_init(&(alp)->lock_data)
   #define simple_lock(alp)        __cpu_simple_lock(&(alp)->lock_data)
   #define simple_lock_try(alp)    __cpu_simple_lock_try(&(alp)->lock_data)
   #define simple_unlock(alp)      __cpu_simple_unlock(&(alp)->lock_data)
   #define LOCK_ASSERT(x)          /* nothing */
   #define simple_lock_only_held(x,y)              /* nothing */
   #define simple_lock_assert_locked(alp,lockname) /* nothing */
   #define simple_lock_assert_unlocked(alp,lockname)       /* nothing */
   #else
   #define simple_lock_try(alp)    (1)
   #ifndef __lint__
   #define simple_lock_init(alp)   (void)(alp)
   #define simple_lock(alp)        (void)(alp)
   #define simple_unlock(alp)      (void)(alp)
   #define simple_lock_assert_locked(alp,lockname) (void)(alp)
   #define simple_lock_assert_unlocked(alp,lockname)       (void)(alp)
   #else /* __lint__ */
   #define simple_lock_init(alp)   /* nothing */
   #define simple_lock(alp)        /* nothing */
   #define simple_unlock(alp)      /* nothing */
   #define simple_lock_only_held(x,y)              /* nothing */
   #define simple_lock_assert_locked(alp,lockname) /* nothing */
   #define simple_lock_assert_unlocked(alp,lockname)       /* nothing */
   #endif /* __lint__ */
   #define LOCK_ASSERT(x)          /* nothing */
   #endif
   
   int     lock_owner_onproc(uintptr_t);
   
   #ifndef SPINLOCK_SPIN_HOOK              /* from <machine/lock.h> */
   #define SPINLOCK_SPIN_HOOK              /* nothing */
   #endif
   
   #ifndef SPINLOCK_BACKOFF_MIN
   #define SPINLOCK_BACKOFF_MIN    32
   #endif
   #ifndef SPINLOCK_BACKOFF_MAX
   #define SPINLOCK_BACKOFF_MAX    1024
   #endif
   #define SPINLOCK_BACKOFF(count)                                 \
   do {                                                            \
           int __i;                                                \
           for (__i = 0; __i < (count); __i++) {                   \
                   SPINLOCK_SPIN_HOOK;                             \
                   nullop(NULL);                                   \
           }                                                       \
           if ((__i <<= 1) <= SPINLOCK_BACKOFF_MAX)                \
                   (count) = SPINLOCK_BACKOFF_MAX;                 \
   } while (/* CONSTCOND */ 0);
   
   #endif /* _KERNEL */
   
   #endif /* _SYS_LOCK_H_ */

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