The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/sys/lock.h

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    1 /*-
    2  * Copyright (c) 1997 Berkeley Software Design, Inc. All rights reserved.
    3  *
    4  * Redistribution and use in source and binary forms, with or without
    5  * modification, are permitted provided that the following conditions
    6  * are met:
    7  * 1. Redistributions of source code must retain the above copyright
    8  *    notice, this list of conditions and the following disclaimer.
    9  * 2. Redistributions in binary form must reproduce the above copyright
   10  *    notice, this list of conditions and the following disclaimer in the
   11  *    documentation and/or other materials provided with the distribution.
   12  * 3. Berkeley Software Design Inc's name may not be used to endorse or
   13  *    promote products derived from this software without specific prior
   14  *    written permission.
   15  *
   16  * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND
   17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   19  * ARE DISCLAIMED.  IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE
   20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   26  * SUCH DAMAGE.
   27  *
   28  *      from BSDI Id: mutex.h,v 2.7.2.35 2000/04/27 03:10:26 cp
   29  * $FreeBSD$
   30  */
   31 
   32 #ifndef _SYS_LOCK_H_
   33 #define _SYS_LOCK_H_
   34 
   35 #include <sys/queue.h>
   36 #include <sys/_lock.h>
   37 
   38 struct lock_list_entry;
   39 struct thread;
   40 
   41 /*
   42  * Lock classes.  Each lock has a class which describes characteristics
   43  * common to all types of locks of a given class.
   44  *
   45  * Spin locks in general must always protect against preemption, as it is
   46  * an error to perform any type of context switch while holding a spin lock.
   47  * Also, for an individual lock to be recursable, its class must allow
   48  * recursion and the lock itself must explicitly allow recursion.
   49  *
   50  * The 'lc_ddb_show' function pointer is used to dump class-specific
   51  * data for the 'show lock' DDB command.  The 'lc_lock' and
   52  * 'lc_unlock' function pointers are used in sleep(9) and cv_wait(9)
   53  * to lock and unlock locks while blocking on a sleep queue.  The
   54  * return value of 'lc_unlock' will be passed to 'lc_lock' on resume
   55  * to allow communication of state between the two routines.
   56  */
   57 
   58 struct lock_class {
   59         const   char *lc_name;
   60         u_int   lc_flags;
   61         void    (*lc_assert)(struct lock_object *lock, int what);
   62         void    (*lc_ddb_show)(struct lock_object *lock);
   63         void    (*lc_lock)(struct lock_object *lock, int how);
   64         int     (*lc_owner)(struct lock_object *lock, struct thread **owner);
   65         int     (*lc_unlock)(struct lock_object *lock);
   66 };
   67 
   68 #define LC_SLEEPLOCK    0x00000001      /* Sleep lock. */
   69 #define LC_SPINLOCK     0x00000002      /* Spin lock. */
   70 #define LC_SLEEPABLE    0x00000004      /* Sleeping allowed with this lock. */
   71 #define LC_RECURSABLE   0x00000008      /* Locks of this type may recurse. */
   72 #define LC_UPGRADABLE   0x00000010      /* Upgrades and downgrades permitted. */
   73 
   74 #define LO_CLASSFLAGS   0x0000ffff      /* Class specific flags. */
   75 #define LO_INITIALIZED  0x00010000      /* Lock has been initialized. */
   76 #define LO_WITNESS      0x00020000      /* Should witness monitor this lock. */
   77 #define LO_QUIET        0x00040000      /* Don't log locking operations. */
   78 #define LO_RECURSABLE   0x00080000      /* Lock may recurse. */
   79 #define LO_SLEEPABLE    0x00100000      /* Lock may be held while sleeping. */
   80 #define LO_UPGRADABLE   0x00200000      /* Lock may be upgraded/downgraded. */
   81 #define LO_DUPOK        0x00400000      /* Don't check for duplicate acquires */
   82 #define LO_CLASSMASK    0x0f000000      /* Class index bitmask. */
   83 #define LO_NOPROFILE    0x10000000      /* Don't profile this lock */
   84 
   85 /*
   86  * Lock classes are statically assigned an index into the gobal lock_classes
   87  * array.  Debugging code looks up the lock class for a given lock object
   88  * by indexing the array.
   89  */
   90 #define LO_CLASSSHIFT           24
   91 #define LO_CLASSINDEX(lock)     ((((lock)->lo_flags) & LO_CLASSMASK) >> LO_CLASSSHIFT)
   92 #define LOCK_CLASS(lock)        (lock_classes[LO_CLASSINDEX((lock))])
   93 #define LOCK_CLASS_MAX          (LO_CLASSMASK >> LO_CLASSSHIFT)
   94 
   95 /*
   96  * Option flags passed to lock operations that witness also needs to know
   97  * about or that are generic across all locks.
   98  */
   99 #define LOP_NEWORDER    0x00000001      /* Define a new lock order. */
  100 #define LOP_QUIET       0x00000002      /* Don't log locking operations. */
  101 #define LOP_TRYLOCK     0x00000004      /* Don't check lock order. */
  102 #define LOP_EXCLUSIVE   0x00000008      /* Exclusive lock. */
  103 #define LOP_DUPOK       0x00000010      /* Don't check for duplicate acquires */
  104 
  105 /* Flags passed to witness_assert. */
  106 #define LA_MASKASSERT   0x000000ff      /* Mask for witness defined asserts. */
  107 #define LA_UNLOCKED     0x00000000      /* Lock is unlocked. */
  108 #define LA_LOCKED       0x00000001      /* Lock is at least share locked. */
  109 #define LA_SLOCKED      0x00000002      /* Lock is exactly share locked. */
  110 #define LA_XLOCKED      0x00000004      /* Lock is exclusively locked. */
  111 #define LA_RECURSED     0x00000008      /* Lock is recursed. */
  112 #define LA_NOTRECURSED  0x00000010      /* Lock is not recursed. */
  113 
  114 #ifdef _KERNEL
  115 /*
  116  * If any of WITNESS, INVARIANTS, or KTR_LOCK KTR tracing has been enabled,
  117  * then turn on LOCK_DEBUG.  When this option is on, extra debugging
  118  * facilities such as tracking the file and line number of lock operations
  119  * are enabled.  Also, mutex locking operations are not inlined to avoid
  120  * bloat from all the extra debugging code.  We also have to turn on all the
  121  * calling conventions for this debugging code in modules so that modules can
  122  * work with both debug and non-debug kernels.
  123  */
  124 #if defined(KLD_MODULE) || defined(WITNESS) || defined(INVARIANTS) || defined(INVARIANT_SUPPORT) || defined(KTR) || defined(LOCK_PROFILING)
  125 #define LOCK_DEBUG      1
  126 #else
  127 #define LOCK_DEBUG      0
  128 #endif
  129 
  130 /*
  131  * In the LOCK_DEBUG case, use the filename and line numbers for debugging
  132  * operations.  Otherwise, use default values to avoid the unneeded bloat.
  133  */
  134 #if LOCK_DEBUG > 0
  135 #define LOCK_FILE       __FILE__
  136 #define LOCK_LINE       __LINE__
  137 #else
  138 #define LOCK_FILE       NULL
  139 #define LOCK_LINE       0
  140 #endif
  141 
  142 /*
  143  * Macros for KTR_LOCK tracing.
  144  *
  145  * opname  - name of this operation (LOCK/UNLOCK/SLOCK, etc.)
  146  * lo      - struct lock_object * for this lock
  147  * flags   - flags passed to the lock operation
  148  * recurse - this locks recursion level (or 0 if class is not recursable)
  149  * result  - result of a try lock operation
  150  * file    - file name
  151  * line    - line number
  152  */
  153 #define LOCK_LOG_TEST(lo, flags)                                        \
  154         (((flags) & LOP_QUIET) == 0 && ((lo)->lo_flags & LO_QUIET) == 0)
  155 
  156 #define LOCK_LOG_LOCK(opname, lo, flags, recurse, file, line) do {      \
  157         if (LOCK_LOG_TEST((lo), (flags)))                               \
  158                 CTR6(KTR_LOCK, opname " (%s) %s %p r = %d at %s:%d",    \
  159                     LOCK_CLASS(lo)->lc_name, (lo)->lo_name,             \
  160                     (lo), (u_int)(recurse), (file), (line));            \
  161 } while (0)
  162 
  163 #define LOCK_LOG_TRY(opname, lo, flags, result, file, line) do {        \
  164         if (LOCK_LOG_TEST((lo), (flags)))                               \
  165                 CTR6(KTR_LOCK, "TRY_" opname " (%s) %s %p result=%d at %s:%d",\
  166                     LOCK_CLASS(lo)->lc_name, (lo)->lo_name,             \
  167                     (lo), (u_int)(result), (file), (line));             \
  168 } while (0)
  169 
  170 #define LOCK_LOG_INIT(lo, flags) do {                                   \
  171         if (LOCK_LOG_TEST((lo), (flags)))                               \
  172                 CTR4(KTR_LOCK, "%s: %p (%s) %s", __func__, (lo),        \
  173                     LOCK_CLASS(lo)->lc_name, (lo)->lo_name);            \
  174 } while (0)
  175 
  176 #define LOCK_LOG_DESTROY(lo, flags)     LOCK_LOG_INIT(lo, flags)
  177 
  178 #define lock_initalized(lo)     ((lo)->lo_flags & LO_INITIALIZED)
  179 
  180 /*
  181  * Helpful macros for quickly coming up with assertions with informative
  182  * panic messages.
  183  */
  184 #define MPASS(ex)               MPASS4(ex, #ex, __FILE__, __LINE__)
  185 #define MPASS2(ex, what)        MPASS4(ex, what, __FILE__, __LINE__)
  186 #define MPASS3(ex, file, line)  MPASS4(ex, #ex, file, line)
  187 #define MPASS4(ex, what, file, line)                                    \
  188         KASSERT((ex), ("Assertion %s failed at %s:%d", what, file, line))
  189 
  190 extern struct lock_class lock_class_mtx_sleep;
  191 extern struct lock_class lock_class_mtx_spin;
  192 extern struct lock_class lock_class_sx;
  193 extern struct lock_class lock_class_rw;
  194 extern struct lock_class lock_class_rm;
  195 extern struct lock_class lock_class_rm_sleepable;
  196 extern struct lock_class lock_class_lockmgr;
  197 
  198 extern struct lock_class *lock_classes[];
  199 
  200 void    lock_init(struct lock_object *, struct lock_class *,
  201             const char *, const char *, int);
  202 void    lock_destroy(struct lock_object *);
  203 void    spinlock_enter(void);
  204 void    spinlock_exit(void);
  205 void    witness_init(struct lock_object *, const char *);
  206 void    witness_destroy(struct lock_object *);
  207 int     witness_defineorder(struct lock_object *, struct lock_object *);
  208 void    witness_checkorder(struct lock_object *, int, const char *, int,
  209             struct lock_object *);
  210 void    witness_lock(struct lock_object *, int, const char *, int);
  211 void    witness_upgrade(struct lock_object *, int, const char *, int);
  212 void    witness_downgrade(struct lock_object *, int, const char *, int);
  213 void    witness_unlock(struct lock_object *, int, const char *, int);
  214 void    witness_save(struct lock_object *, const char **, int *);
  215 void    witness_restore(struct lock_object *, const char *, int);
  216 int     witness_list_locks(struct lock_list_entry **,
  217             int (*)(const char *, ...));
  218 int     witness_warn(int, struct lock_object *, const char *, ...);
  219 void    witness_assert(struct lock_object *, int, const char *, int);
  220 void    witness_display_spinlock(struct lock_object *, struct thread *,
  221             int (*)(const char *, ...));
  222 int     witness_line(struct lock_object *);
  223 void    witness_norelease(struct lock_object *);
  224 void    witness_releaseok(struct lock_object *);
  225 const char *witness_file(struct lock_object *);
  226 void    witness_thread_exit(struct thread *);
  227 
  228 #ifdef  WITNESS
  229 
  230 /* Flags for witness_warn(). */
  231 #define WARN_GIANTOK    0x01    /* Giant is exempt from this check. */
  232 #define WARN_PANIC      0x02    /* Panic if check fails. */
  233 #define WARN_SLEEPOK    0x04    /* Sleepable locks are exempt from check. */
  234 
  235 #define WITNESS_INIT(lock, type)                                        \
  236         witness_init((lock), (type))
  237 
  238 #define WITNESS_DESTROY(lock)                                           \
  239         witness_destroy(lock)
  240 
  241 #define WITNESS_CHECKORDER(lock, flags, file, line, interlock)          \
  242         witness_checkorder((lock), (flags), (file), (line), (interlock))
  243 
  244 #define WITNESS_DEFINEORDER(lock1, lock2)                               \
  245         witness_defineorder((struct lock_object *)(lock1),              \
  246             (struct lock_object *)(lock2))
  247 
  248 #define WITNESS_LOCK(lock, flags, file, line)                           \
  249         witness_lock((lock), (flags), (file), (line))
  250 
  251 #define WITNESS_UPGRADE(lock, flags, file, line)                        \
  252         witness_upgrade((lock), (flags), (file), (line))
  253 
  254 #define WITNESS_DOWNGRADE(lock, flags, file, line)                      \
  255         witness_downgrade((lock), (flags), (file), (line))
  256 
  257 #define WITNESS_UNLOCK(lock, flags, file, line)                         \
  258         witness_unlock((lock), (flags), (file), (line))
  259 
  260 #define WITNESS_CHECK(flags, lock, fmt, ...)                            \
  261         witness_warn((flags), (lock), (fmt), ## __VA_ARGS__)
  262 
  263 #define WITNESS_WARN(flags, lock, fmt, ...)                             \
  264         witness_warn((flags), (lock), (fmt), ## __VA_ARGS__)
  265 
  266 #define WITNESS_SAVE_DECL(n)                                            \
  267         const char * __CONCAT(n, __wf);                                 \
  268         int __CONCAT(n, __wl)
  269 
  270 #define WITNESS_SAVE(lock, n)                                           \
  271         witness_save((lock), &__CONCAT(n, __wf), &__CONCAT(n, __wl))
  272 
  273 #define WITNESS_RESTORE(lock, n)                                        \
  274         witness_restore((lock), __CONCAT(n, __wf), __CONCAT(n, __wl))
  275 
  276 #define WITNESS_NORELEASE(lock)                                         \
  277         witness_norelease(&(lock)->lock_object)
  278 
  279 #define WITNESS_RELEASEOK(lock)                                         \
  280         witness_releaseok(&(lock)->lock_object)
  281 
  282 #define WITNESS_FILE(lock)                                              \
  283         witness_file(lock)
  284 
  285 #define WITNESS_LINE(lock)                                              \
  286         witness_line(lock)
  287 
  288 #else   /* WITNESS */
  289 #define WITNESS_INIT(lock, type)                                (void)0
  290 #define WITNESS_DESTROY(lock)                                   (void)0
  291 #define WITNESS_DEFINEORDER(lock1, lock2)       0
  292 #define WITNESS_CHECKORDER(lock, flags, file, line, interlock)  (void)0
  293 #define WITNESS_LOCK(lock, flags, file, line)                   (void)0
  294 #define WITNESS_UPGRADE(lock, flags, file, line)                (void)0
  295 #define WITNESS_DOWNGRADE(lock, flags, file, line)              (void)0
  296 #define WITNESS_UNLOCK(lock, flags, file, line)                 (void)0
  297 #define WITNESS_CHECK(flags, lock, fmt, ...)    0
  298 #define WITNESS_WARN(flags, lock, fmt, ...)                     (void)0
  299 #define WITNESS_SAVE_DECL(n)                                    (void)0
  300 #define WITNESS_SAVE(lock, n)                                   (void)0
  301 #define WITNESS_RESTORE(lock, n)                                (void)0
  302 #define WITNESS_NORELEASE(lock)                                 (void)0
  303 #define WITNESS_RELEASEOK(lock)                                 (void)0
  304 #define WITNESS_FILE(lock) ("?")
  305 #define WITNESS_LINE(lock) (0)
  306 #endif  /* WITNESS */
  307 
  308 /*
  309  * Helper macros to allow developers to add explicit lock order checks
  310  * wherever they please without having to actually grab a lock to do so.
  311  */
  312 #define witness_check(l)                                                \
  313         WITNESS_CHECKORDER(&(l)->lock_object, LOP_EXCLUSIVE, LOCK_FILE, \
  314             LOCK_LINE, NULL)
  315 
  316 #define witness_check_shared(l)                                         \
  317         WITNESS_CHECKORDER(&(l)->lock_object, 0, LOCK_FILE, LOCK_LINE, NULL)
  318         
  319 #endif  /* _KERNEL */
  320 #endif  /* _SYS_LOCK_H_ */

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