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

     /*-
      * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
      *
      * 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
     * $FreeBSD$
     */
    
    #ifndef _SYS_LOCK_H_
    #define _SYS_LOCK_H_
    
    #include <sys/queue.h>
    #include <sys/_lock.h>
    #include <sys/ktr_class.h>
    
    struct lock_list_entry;
    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.
     *
     * The 'lc_ddb_show' function pointer is used to dump class-specific
     * data for the 'show lock' DDB command.  The 'lc_lock' and
     * 'lc_unlock' function pointers are used in sleep(9) and cv_wait(9)
     * to lock and unlock locks while blocking on a sleep queue.  The
     * return value of 'lc_unlock' will be passed to 'lc_lock' on resume
     * to allow communication of state between the two routines.
     */
    
    struct lock_class {
            const           char *lc_name;
            u_int           lc_flags;
            void            (*lc_assert)(const struct lock_object *lock, int what);
            void            (*lc_ddb_show)(const struct lock_object *lock);
            void            (*lc_lock)(struct lock_object *lock, uintptr_t how);
            int             (*lc_owner)(const struct lock_object *lock,
                                struct thread **owner);
            uintptr_t       (*lc_unlock)(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 LO_IS_VNODE     0x00800000      /* Tell WITNESS about a VNODE lock */
    #define LO_CLASSMASK    0x0f000000      /* Class index bitmask. */
    #define LO_NOPROFILE    0x10000000      /* Don't profile this lock */
    #define LO_NEW          0x20000000      /* Don't check for double-init */
    
    /*
     * Lock classes are statically assigned an index into the gobal lock_classes
     * array.  Debugging code looks up the lock class for a given lock object
     * by indexing the array.
     */
    #define LO_CLASSSHIFT           24
    #define LO_CLASSINDEX(lock)     ((((lock)->lo_flags) & LO_CLASSMASK) >> LO_CLASSSHIFT)
    #define LOCK_CLASS(lock)        (lock_classes[LO_CLASSINDEX((lock))])
    #define LOCK_CLASS_MAX          (LO_CLASSMASK >> LO_CLASSSHIFT)
   
   /*
    * 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 */
   #define LOP_NOSLEEP     0x00000020      /* Non-sleepable despite LO_SLEEPABLE */
   
   /* Flags passed to witness_assert. */
   #define LA_MASKASSERT   0x000000ff      /* Mask for witness defined asserts. */
   #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
   /*
    * 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
    */
   #if LOCK_DEBUG > 0
   #define LOCK_LOG_TEST(lo, flags)                                        \
           (((flags) & LOP_QUIET) == 0 && ((lo)->lo_flags & LO_QUIET) == 0)
   #else
   #define LOCK_LOG_TEST(lo, flags)        0
   #endif
   
   #define LOCK_LOG_LOCK(opname, lo, flags, recurse, file, line) do {      \
           if (LOCK_LOG_TEST((lo), (flags)))                               \
                   CTR6(KTR_LOCK, opname " (%s) %s %p r = %d at %s:%d",    \
                       LOCK_CLASS(lo)->lc_name, (lo)->lo_name,             \
                       (lo), (u_int)(recurse), (file), (line));            \
   } while (0)
   
   #define LOCK_LOG_TRY(opname, lo, flags, result, file, line) do {        \
           if (LOCK_LOG_TEST((lo), (flags)))                               \
                   CTR6(KTR_LOCK, "TRY_" opname " (%s) %s %p result=%d at %s:%d",\
                       LOCK_CLASS(lo)->lc_name, (lo)->lo_name,             \
                       (lo), (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),        \
                       LOCK_CLASS(lo)->lc_name, (lo)->lo_name);            \
   } while (0)
   
   #define LOCK_LOG_DESTROY(lo, flags)     LOCK_LOG_INIT(lo, flags)
   
   #define lock_initialized(lo)    ((lo)->lo_flags & LO_INITIALIZED)
   
   extern struct lock_class lock_class_mtx_sleep;
   extern struct lock_class lock_class_mtx_spin;
   extern struct lock_class lock_class_sx;
   extern struct lock_class lock_class_rw;
   extern struct lock_class lock_class_rm;
   extern struct lock_class lock_class_rm_sleepable;
   extern struct lock_class lock_class_lockmgr;
   
   extern struct lock_class *lock_classes[];
   
   struct lock_delay_config {
           u_short base;
           u_short max;
   };
   
   extern struct lock_delay_config locks_delay;
   extern u_short locks_delay_retries;
   extern u_short locks_delay_loops;
   
   struct lock_delay_arg {
           struct lock_delay_config *config;
           u_short delay;
           u_int spin_cnt;
   };
   
   static inline void
   lock_delay_arg_init(struct lock_delay_arg *la, struct lock_delay_config *lc)
   {
           la->config = lc;
           la->delay = lc->base;
           la->spin_cnt = 0;
   }
   
   static inline void
   lock_delay_arg_init_noadapt(struct lock_delay_arg *la)
   {
           la->delay = 0;
           la->spin_cnt = 0;
   }
   
   #define lock_delay_spin(n)      do {    \
           u_int _i;                       \
                                           \
           for (_i = (n); _i > 0; _i--)    \
                   cpu_spinwait();         \
   } while (0)
   
   #define LOCK_DELAY_SYSINIT(func) \
           SYSINIT(func##_ld, SI_SUB_LOCK, SI_ORDER_ANY, func, NULL)
   
   #define LOCK_DELAY_SYSINIT_DEFAULT(lc) \
           SYSINIT(lock_delay_##lc##_ld, SI_SUB_LOCK, SI_ORDER_ANY, \
               lock_delay_default_init, &lc)
   
   void    lock_init(struct lock_object *, struct lock_class *,
               const char *, const char *, int);
   void    lock_destroy(struct lock_object *);
   void    lock_delay(struct lock_delay_arg *);
   void    lock_delay_default_init(struct lock_delay_config *);
   void    spinlock_enter(void);
   void    spinlock_exit(void);
   void    witness_init(struct lock_object *, const char *);
   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,
               struct lock_object *);
   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 (*)(const char *, ...));
   int     witness_warn(int, struct lock_object *, const char *, ...);
   void    witness_assert(const struct lock_object *, int, const char *, int);
   void    witness_display_spinlock(struct lock_object *, struct thread *,
               int (*)(const char *, ...));
   int     witness_line(struct lock_object *);
   void    witness_norelease(struct lock_object *);
   void    witness_releaseok(struct lock_object *);
   const char *witness_file(struct lock_object *);
   void    witness_thread_exit(struct thread *);
   
   #ifdef  WITNESS
   int     witness_startup_count(void);
   void    witness_startup(void *);
   
   /* 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, type)                                        \
           witness_init((lock), (type))
   
   #define WITNESS_DESTROY(lock)                                           \
           witness_destroy(lock)
   
   #define WITNESS_CHECKORDER(lock, flags, file, line, interlock)          \
           witness_checkorder((lock), (flags), (file), (line), (interlock))
   
   #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_CHECK(flags, lock, fmt, ...)                            \
           witness_warn((flags), (lock), (fmt), ## __VA_ARGS__)
   
   #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_NORELEASE(lock)                                         \
           witness_norelease(&(lock)->lock_object)
   
   #define WITNESS_RELEASEOK(lock)                                         \
           witness_releaseok(&(lock)->lock_object)
   
   #define WITNESS_FILE(lock)                                              \
           witness_file(lock)
   
   #define WITNESS_LINE(lock)                                              \
           witness_line(lock)
   
   #else   /* WITNESS */
   #define WITNESS_INIT(lock, type)                                (void)0
   #define WITNESS_DESTROY(lock)                                   (void)0
   #define WITNESS_DEFINEORDER(lock1, lock2)       0
   #define WITNESS_CHECKORDER(lock, flags, file, line, interlock)  (void)0
   #define WITNESS_LOCK(lock, flags, file, line)                   (void)0
   #define WITNESS_UPGRADE(lock, flags, file, line)                (void)0
   #define WITNESS_DOWNGRADE(lock, flags, file, line)              (void)0
   #define WITNESS_UNLOCK(lock, flags, file, line)                 (void)0
   #define WITNESS_CHECK(flags, lock, fmt, ...)    0
   #define WITNESS_WARN(flags, lock, fmt, ...)                     (void)0
   #define WITNESS_SAVE_DECL(n)                                    (void)0
   #define WITNESS_SAVE(lock, n)                                   (void)0
   #define WITNESS_RESTORE(lock, n)                                (void)0
   #define WITNESS_NORELEASE(lock)                                 (void)0
   #define WITNESS_RELEASEOK(lock)                                 (void)0
   #define WITNESS_FILE(lock) ("?")
   #define WITNESS_LINE(lock) (0)
   #endif  /* WITNESS */
   
   #endif  /* _KERNEL */
   #endif  /* _SYS_LOCK_H_ */

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