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

     /*-
      * Copyright (c) 1997 Berkeley Software Design, Inc. All rights reserved.
      *
      * 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. Berkeley Software Design Inc's name may not be used to endorse or
     *    promote products derived from this software without specific prior
     *    written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``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 BERKELEY SOFTWARE DESIGN INC 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.
     *
     *      from BSDI $Id: mutex.h,v 2.7.2.35 2000/04/27 03:10:26 cp Exp $
     * $FreeBSD: releng/6.1/sys/sys/lock.h 158179 2006-04-30 16:44:43Z cvs2svn $
     */
    
    #ifndef _SYS_LOCK_H_
    #define _SYS_LOCK_H_
    
    #include <sys/queue.h>
    #include <sys/_lock.h>
    
    struct thread;
    
    /*
     * Lock classes.  Each lock has a class which describes characteristics
     * common to all types of locks of a given class.
     *
     * Spin locks in general must always protect against preemption, as it is
     * an error to perform any type of context switch while holding a spin lock.
     * Also, for an individual lock to be recursable, its class must allow
     * recursion and the lock itself must explicitly allow recursion.
     */
    
    struct lock_class {
            const   char *lc_name;
            u_int   lc_flags;
            void    (*lc_ddb_show)(struct lock_object *lock);
    };
    
    #define LC_SLEEPLOCK    0x00000001      /* Sleep lock. */
    #define LC_SPINLOCK     0x00000002      /* Spin lock. */
    #define LC_SLEEPABLE    0x00000004      /* Sleeping allowed with this lock. */
    #define LC_RECURSABLE   0x00000008      /* Locks of this type may recurse. */
    #define LC_UPGRADABLE   0x00000010      /* Upgrades and downgrades permitted. */
    
    #define LO_CLASSFLAGS   0x0000ffff      /* Class specific flags. */
    #define LO_INITIALIZED  0x00010000      /* Lock has been initialized. */
    #define LO_WITNESS      0x00020000      /* Should witness monitor this lock. */
    #define LO_QUIET        0x00040000      /* Don't log locking operations. */
    #define LO_RECURSABLE   0x00080000      /* Lock may recurse. */
    #define LO_SLEEPABLE    0x00100000      /* Lock may be held while sleeping. */
    #define LO_UPGRADABLE   0x00200000      /* Lock may be upgraded/downgraded. */
    #define LO_DUPOK        0x00400000      /* Don't check for duplicate acquires */
    
    #define LI_RECURSEMASK  0x0000ffff      /* Recursion depth of lock instance. */
    #define LI_EXCLUSIVE    0x00010000      /* Exclusive lock instance. */
    
    /*
     * Option flags passed to lock operations that witness also needs to know
     * about or that are generic across all locks.
     */
    #define LOP_NEWORDER    0x00000001      /* Define a new lock order. */
    #define LOP_QUIET       0x00000002      /* Don't log locking operations. */
    #define LOP_TRYLOCK     0x00000004      /* Don't check lock order. */
    #define LOP_EXCLUSIVE   0x00000008      /* Exclusive lock. */
    #define LOP_DUPOK       0x00000010      /* Don't check for duplicate acquires */
    
    /* Flags passed to witness_assert. */
    #define LA_UNLOCKED     0x00000000      /* Lock is unlocked. */
    #define LA_LOCKED       0x00000001      /* Lock is at least share locked. */
    #define LA_SLOCKED      0x00000002      /* Lock is exactly share locked. */
    #define LA_XLOCKED      0x00000004      /* Lock is exclusively locked. */
    #define LA_RECURSED     0x00000008      /* Lock is recursed. */
    #define LA_NOTRECURSED  0x00000010      /* Lock is not recursed. */
    
    #ifdef _KERNEL
    /*
     * Lock instances.  A lock instance is the data associated with a lock while
     * it is held by witness.  For example, a lock instance will hold the
     * recursion count of a lock.  Lock instances are held in lists.  Spin locks
     * are held in a per-cpu list while sleep locks are held in per-process list.
     */
    struct lock_instance {
           struct  lock_object *li_lock;
           const   char *li_file;          /* File and line of last acquire. */
           int     li_line;
           u_int   li_flags;               /* Recursion count and LI_* flags. */
   };
   
   /*
    * A simple list type used to build the list of locks held by a process
    * or CPU.  We can't simply embed the list in struct lock_object since a
    * lock may be held by more than one process if it is a shared lock.  Locks
    * are added to the head of the list, so we fill up each list entry from
    * "the back" logically.  To ease some of the arithmetic, we actually fill
    * in each list entry the normal way (childer[0] then children[1], etc.) but
    * when we traverse the list we read children[count-1] as the first entry
    * down to children[0] as the final entry.
    */
   #define LOCK_NCHILDREN  3
   
   struct lock_list_entry {
           struct  lock_list_entry *ll_next;
           struct  lock_instance ll_children[LOCK_NCHILDREN];
           u_int   ll_count;
   };
   
   /*
    * If any of WITNESS, INVARIANTS, or KTR_LOCK KTR tracing has been enabled,
    * then turn on LOCK_DEBUG.  When this option is on, extra debugging
    * facilities such as tracking the file and line number of lock operations
    * are enabled.  Also, mutex locking operations are not inlined to avoid
    * bloat from all the extra debugging code.  We also have to turn on all the
    * calling conventions for this debugging code in modules so that modules can
    * work with both debug and non-debug kernels.
    */
   #if defined(KLD_MODULE) || defined(WITNESS) || defined(INVARIANTS) || defined(INVARIANT_SUPPORT) || defined(KTR) || defined(MUTEX_PROFILING)
   #define LOCK_DEBUG      1
   #else
   #define LOCK_DEBUG      0
   #endif
   
   /*
    * In the LOCK_DEBUG case, use the filename and line numbers for debugging
    * operations.  Otherwise, use default values to avoid the unneeded bloat.
    */
   #if LOCK_DEBUG > 0
   #define LOCK_FILE       __FILE__
   #define LOCK_LINE       __LINE__
   #else
   #define LOCK_FILE       NULL
   #define LOCK_LINE       0
   #endif
   
   /*
    * Macros for KTR_LOCK tracing.
    *
    * opname  - name of this operation (LOCK/UNLOCK/SLOCK, etc.)
    * lo      - struct lock_object * for this lock
    * flags   - flags passed to the lock operation
    * recurse - this locks recursion level (or 0 if class is not recursable)
    * result  - result of a try lock operation
    * file    - file name
    * line    - line number
    */
   #define LOCK_LOG_TEST(lo, flags)                                        \
           (((flags) & LOP_QUIET) == 0 && ((lo)->lo_flags & LO_QUIET) == 0)
   
   #define LOCK_LOG_LOCK(opname, lo, flags, recurse, file, line) do {      \
           if (LOCK_LOG_TEST((lo), (flags)))                               \
                   CTR5(KTR_LOCK, opname " (%s) %s r = %d at %s:%d",       \
                       (lo)->lo_class->lc_name, (lo)->lo_name,             \
                       (u_int)(recurse), (file), (line));                  \
   } while (0)
   
   #define LOCK_LOG_TRY(opname, lo, flags, result, file, line) do {        \
           if (LOCK_LOG_TEST((lo), (flags)))                               \
                   CTR5(KTR_LOCK, "TRY_" opname " (%s) %s result=%d at %s:%d",\
                       (lo)->lo_class->lc_name, (lo)->lo_name,             \
                       (u_int)(result), (file), (line));                   \
   } while (0)
   
   #define LOCK_LOG_INIT(lo, flags) do {                                   \
           if (LOCK_LOG_TEST((lo), (flags)))                               \
                   CTR4(KTR_LOCK, "%s: %p (%s) %s", __func__, (lo),        \
                       (lo)->lo_class->lc_name, (lo)->lo_name);            \
   } while (0)
   
   #define LOCK_LOG_DESTROY(lo, flags)     LOCK_LOG_INIT(lo, flags)
   
   /*
    * Helpful macros for quickly coming up with assertions with informative
    * panic messages.
    */
   #define MPASS(ex)               MPASS4(ex, #ex, __FILE__, __LINE__)
   #define MPASS2(ex, what)        MPASS4(ex, what, __FILE__, __LINE__)
   #define MPASS3(ex, file, line)  MPASS4(ex, #ex, file, line)
   #define MPASS4(ex, what, file, line)                                    \
           KASSERT((ex), ("Assertion %s failed at %s:%d", what, file, line))
   
   extern struct lock_class lock_class_mtx_sleep;
   extern struct lock_class lock_class_mtx_spin;
   extern struct lock_class lock_class_sx;
   
   void    spinlock_enter(void);
   void    spinlock_exit(void);
   void    witness_init(struct lock_object *);
   void    witness_destroy(struct lock_object *);
   int     witness_defineorder(struct lock_object *, struct lock_object *);
   void    witness_checkorder(struct lock_object *, int, const char *, int);
   void    witness_lock(struct lock_object *, int, const char *, int);
   void    witness_upgrade(struct lock_object *, int, const char *, int);
   void    witness_downgrade(struct lock_object *, int, const char *, int);
   void    witness_unlock(struct lock_object *, int, const char *, int);
   void    witness_save(struct lock_object *, const char **, int *);
   void    witness_restore(struct lock_object *, const char *, int);
   int     witness_list_locks(struct lock_list_entry **);
   int     witness_warn(int, struct lock_object *, const char *, ...);
   void    witness_assert(struct lock_object *, int, const char *, int);
   void    witness_display_spinlock(struct lock_object *, struct thread *);
   int     witness_line(struct lock_object *);
   const char *witness_file(struct lock_object *);
   
   #ifdef  WITNESS
   
   /* Flags for witness_warn(). */
   #define WARN_GIANTOK    0x01    /* Giant is exempt from this check. */
   #define WARN_PANIC      0x02    /* Panic if check fails. */
   #define WARN_SLEEPOK    0x04    /* Sleepable locks are exempt from check. */
   
   #define WITNESS_INIT(lock)                                              \
           witness_init((lock))
   
   #define WITNESS_DESTROY(lock)                                           \
           witness_destroy(lock)
   
   #define WITNESS_CHECKORDER(lock, flags, file, line)                     \
           witness_checkorder((lock), (flags), (file), (line))
   
   #define WITNESS_DEFINEORDER(lock1, lock2)                               \
           witness_defineorder((struct lock_object *)(lock1),              \
               (struct lock_object *)(lock2))
   
   #define WITNESS_LOCK(lock, flags, file, line)                           \
           witness_lock((lock), (flags), (file), (line))
   
   #define WITNESS_UPGRADE(lock, flags, file, line)                        \
           witness_upgrade((lock), (flags), (file), (line))
   
   #define WITNESS_DOWNGRADE(lock, flags, file, line)                      \
           witness_downgrade((lock), (flags), (file), (line))
   
   #define WITNESS_UNLOCK(lock, flags, file, line)                         \
           witness_unlock((lock), (flags), (file), (line))
   
   #define WITNESS_WARN(flags, lock, fmt, ...)                             \
           witness_warn((flags), (lock), (fmt), ## __VA_ARGS__)
   
   #define WITNESS_SAVE_DECL(n)                                            \
           const char * __CONCAT(n, __wf);                                 \
           int __CONCAT(n, __wl)
   
   #define WITNESS_SAVE(lock, n)                                           \
           witness_save((lock), &__CONCAT(n, __wf), &__CONCAT(n, __wl))
   
   #define WITNESS_RESTORE(lock, n)                                        \
           witness_restore((lock), __CONCAT(n, __wf), __CONCAT(n, __wl))
   
   #define WITNESS_FILE(lock)                                              \
           witness_file(lock)
   
   #define WITNESS_LINE(lock)                                              \
           witness_line(lock)
   
   #else   /* WITNESS */
   #define WITNESS_INIT(lock)      ((lock)->lo_flags |= LO_INITIALIZED)
   #define WITNESS_DESTROY(lock)   ((lock)->lo_flags &= ~LO_INITIALIZED)
   #define WITNESS_DEFINEORDER(lock1, lock2)       0
   #define WITNESS_CHECKORDER(lock, flags, file, line)
   #define WITNESS_LOCK(lock, flags, file, line)
   #define WITNESS_UPGRADE(lock, flags, file, line)
   #define WITNESS_DOWNGRADE(lock, flags, file, line)
   #define WITNESS_UNLOCK(lock, flags, file, line)
   #define WITNESS_WARN(flags, lock, fmt, ...)
   #define WITNESS_SAVE_DECL(n)
   #define WITNESS_SAVE(lock, n)
   #define WITNESS_RESTORE(lock, n)
   #define WITNESS_FILE(lock) ("?")
   #define WITNESS_LINE(lock) (0)
   #endif  /* WITNESS */
   
   /*
    * Helper macros to allow developers to add explicit lock order checks
    * wherever they please without having to actually grab a lock to do so.
    */
   #define witness_check_mutex(m)                                          \
           WITNESS_CHECKORDER(&(m)->mtx_object, LOP_EXCLUSIVE, LOCK_FILE,  \
               LOCK_LINE)
   
   #define witness_check_shared_sx(sx)                                     \
           WITNESS_CHECKORDER(&(sx)->sx_object, 0, LOCK_FILE, LOCK_LINE)
           
   #define witness_check_exclusive_sx(sx)                                  \
           WITNESS_CHECKORDER(&(sx)->sx_object, LOP_EXCLUSIVE, LOCK_FILE,  \
               LOCK_LINE)
   
   #endif  /* _KERNEL */
   #endif  /* _SYS_LOCK_H_ */

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