The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: 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  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
    3  *
    4  * Copyright (c) 1997 Berkeley Software Design, Inc. All rights reserved.
    5  *
    6  * Redistribution and use in source and binary forms, with or without
    7  * modification, are permitted provided that the following conditions
    8  * are met:
    9  * 1. Redistributions of source code must retain the above copyright
   10  *    notice, this list of conditions and the following disclaimer.
   11  * 2. Redistributions in binary form must reproduce the above copyright
   12  *    notice, this list of conditions and the following disclaimer in the
   13  *    documentation and/or other materials provided with the distribution.
   14  * 3. Berkeley Software Design Inc's name may not be used to endorse or
   15  *    promote products derived from this software without specific prior
   16  *    written permission.
   17  *
   18  * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND
   19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   21  * ARE DISCLAIMED.  IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE
   22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   28  * SUCH DAMAGE.
   29  *
   30  *      from BSDI Id: mutex.h,v 2.7.2.35 2000/04/27 03:10:26 cp
   31  * $FreeBSD: head/sys/sys/lock.h 335873 2018-07-02 19:48:38Z mmacy $
   32  */
   33 
   34 #ifndef _SYS_LOCK_H_
   35 #define _SYS_LOCK_H_
   36 
   37 #include <sys/queue.h>
   38 #include <sys/_lock.h>
   39 #include <sys/ktr_class.h>
   40 
   41 struct lock_list_entry;
   42 struct thread;
   43 
   44 /*
   45  * Lock classes.  Each lock has a class which describes characteristics
   46  * common to all types of locks of a given class.
   47  *
   48  * Spin locks in general must always protect against preemption, as it is
   49  * an error to perform any type of context switch while holding a spin lock.
   50  * Also, for an individual lock to be recursable, its class must allow
   51  * recursion and the lock itself must explicitly allow recursion.
   52  *
   53  * The 'lc_ddb_show' function pointer is used to dump class-specific
   54  * data for the 'show lock' DDB command.  The 'lc_lock' and
   55  * 'lc_unlock' function pointers are used in sleep(9) and cv_wait(9)
   56  * to lock and unlock locks while blocking on a sleep queue.  The
   57  * return value of 'lc_unlock' will be passed to 'lc_lock' on resume
   58  * to allow communication of state between the two routines.
   59  */
   60 
   61 struct lock_class {
   62         const           char *lc_name;
   63         u_int           lc_flags;
   64         void            (*lc_assert)(const struct lock_object *lock, int what);
   65         void            (*lc_ddb_show)(const struct lock_object *lock);
   66         void            (*lc_lock)(struct lock_object *lock, uintptr_t how);
   67         int             (*lc_owner)(const struct lock_object *lock,
   68                             struct thread **owner);
   69         uintptr_t       (*lc_unlock)(struct lock_object *lock);
   70 };
   71 
   72 #define LC_SLEEPLOCK    0x00000001      /* Sleep lock. */
   73 #define LC_SPINLOCK     0x00000002      /* Spin lock. */
   74 #define LC_SLEEPABLE    0x00000004      /* Sleeping allowed with this lock. */
   75 #define LC_RECURSABLE   0x00000008      /* Locks of this type may recurse. */
   76 #define LC_UPGRADABLE   0x00000010      /* Upgrades and downgrades permitted. */
   77 
   78 #define LO_CLASSFLAGS   0x0000ffff      /* Class specific flags. */
   79 #define LO_INITIALIZED  0x00010000      /* Lock has been initialized. */
   80 #define LO_WITNESS      0x00020000      /* Should witness monitor this lock. */
   81 #define LO_QUIET        0x00040000      /* Don't log locking operations. */
   82 #define LO_RECURSABLE   0x00080000      /* Lock may recurse. */
   83 #define LO_SLEEPABLE    0x00100000      /* Lock may be held while sleeping. */
   84 #define LO_UPGRADABLE   0x00200000      /* Lock may be upgraded/downgraded. */
   85 #define LO_DUPOK        0x00400000      /* Don't check for duplicate acquires */
   86 #define LO_IS_VNODE     0x00800000      /* Tell WITNESS about a VNODE lock */
   87 #define LO_CLASSMASK    0x0f000000      /* Class index bitmask. */
   88 #define LO_NOPROFILE    0x10000000      /* Don't profile this lock */
   89 #define LO_NEW          0x20000000      /* Don't check for double-init */
   90 
   91 /*
   92  * Lock classes are statically assigned an index into the gobal lock_classes
   93  * array.  Debugging code looks up the lock class for a given lock object
   94  * by indexing the array.
   95  */
   96 #define LO_CLASSSHIFT           24
   97 #define LO_CLASSINDEX(lock)     ((((lock)->lo_flags) & LO_CLASSMASK) >> LO_CLASSSHIFT)
   98 #define LOCK_CLASS(lock)        (lock_classes[LO_CLASSINDEX((lock))])
   99 #define LOCK_CLASS_MAX          (LO_CLASSMASK >> LO_CLASSSHIFT)
  100 
  101 /*
  102  * Option flags passed to lock operations that witness also needs to know
  103  * about or that are generic across all locks.
  104  */
  105 #define LOP_NEWORDER    0x00000001      /* Define a new lock order. */
  106 #define LOP_QUIET       0x00000002      /* Don't log locking operations. */
  107 #define LOP_TRYLOCK     0x00000004      /* Don't check lock order. */
  108 #define LOP_EXCLUSIVE   0x00000008      /* Exclusive lock. */
  109 #define LOP_DUPOK       0x00000010      /* Don't check for duplicate acquires */
  110 
  111 /* Flags passed to witness_assert. */
  112 #define LA_MASKASSERT   0x000000ff      /* Mask for witness defined asserts. */
  113 #define LA_UNLOCKED     0x00000000      /* Lock is unlocked. */
  114 #define LA_LOCKED       0x00000001      /* Lock is at least share locked. */
  115 #define LA_SLOCKED      0x00000002      /* Lock is exactly share locked. */
  116 #define LA_XLOCKED      0x00000004      /* Lock is exclusively locked. */
  117 #define LA_RECURSED     0x00000008      /* Lock is recursed. */
  118 #define LA_NOTRECURSED  0x00000010      /* Lock is not recursed. */
  119 
  120 #ifdef _KERNEL
  121 /*
  122  * If any of WITNESS, INVARIANTS, or KTR_LOCK KTR tracing has been enabled,
  123  * then turn on LOCK_DEBUG.  When this option is on, extra debugging
  124  * facilities such as tracking the file and line number of lock operations
  125  * are enabled.  Also, mutex locking operations are not inlined to avoid
  126  * bloat from all the extra debugging code.  We also have to turn on all the
  127  * calling conventions for this debugging code in modules so that modules can
  128  * work with both debug and non-debug kernels.
  129  */
  130 #if (defined(KLD_MODULE) && !defined(KLD_TIED)) || defined(WITNESS) || defined(INVARIANTS) || \
  131     defined(LOCK_PROFILING) || defined(KTR)
  132 #define LOCK_DEBUG      1
  133 #else
  134 #define LOCK_DEBUG      0
  135 #endif
  136 
  137 /*
  138  * In the LOCK_DEBUG case, use the filename and line numbers for debugging
  139  * operations.  Otherwise, use default values to avoid the unneeded bloat.
  140  */
  141 #if LOCK_DEBUG > 0
  142 #define LOCK_FILE_LINE_ARG_DEF  , const char *file, int line
  143 #define LOCK_FILE_LINE_ARG      , file, line
  144 #define LOCK_FILE       __FILE__
  145 #define LOCK_LINE       __LINE__
  146 #else
  147 #define LOCK_FILE_LINE_ARG_DEF
  148 #define LOCK_FILE_LINE_ARG
  149 #define LOCK_FILE       NULL
  150 #define LOCK_LINE       0
  151 #endif
  152 
  153 /*
  154  * Macros for KTR_LOCK tracing.
  155  *
  156  * opname  - name of this operation (LOCK/UNLOCK/SLOCK, etc.)
  157  * lo      - struct lock_object * for this lock
  158  * flags   - flags passed to the lock operation
  159  * recurse - this locks recursion level (or 0 if class is not recursable)
  160  * result  - result of a try lock operation
  161  * file    - file name
  162  * line    - line number
  163  */
  164 #if LOCK_DEBUG > 0
  165 #define LOCK_LOG_TEST(lo, flags)                                        \
  166         (((flags) & LOP_QUIET) == 0 && ((lo)->lo_flags & LO_QUIET) == 0)
  167 #else
  168 #define LOCK_LOG_TEST(lo, flags)        0
  169 #endif
  170 
  171 
  172 #define LOCK_LOG_LOCK(opname, lo, flags, recurse, file, line) do {      \
  173         if (LOCK_LOG_TEST((lo), (flags)))                               \
  174                 CTR6(KTR_LOCK, opname " (%s) %s %p r = %d at %s:%d",    \
  175                     LOCK_CLASS(lo)->lc_name, (lo)->lo_name,             \
  176                     (lo), (u_int)(recurse), (file), (line));            \
  177 } while (0)
  178 
  179 #define LOCK_LOG_TRY(opname, lo, flags, result, file, line) do {        \
  180         if (LOCK_LOG_TEST((lo), (flags)))                               \
  181                 CTR6(KTR_LOCK, "TRY_" opname " (%s) %s %p result=%d at %s:%d",\
  182                     LOCK_CLASS(lo)->lc_name, (lo)->lo_name,             \
  183                     (lo), (u_int)(result), (file), (line));             \
  184 } while (0)
  185 
  186 #define LOCK_LOG_INIT(lo, flags) do {                                   \
  187         if (LOCK_LOG_TEST((lo), (flags)))                               \
  188                 CTR4(KTR_LOCK, "%s: %p (%s) %s", __func__, (lo),        \
  189                     LOCK_CLASS(lo)->lc_name, (lo)->lo_name);            \
  190 } while (0)
  191 
  192 #define LOCK_LOG_DESTROY(lo, flags)     LOCK_LOG_INIT(lo, flags)
  193 
  194 #define lock_initialized(lo)    ((lo)->lo_flags & LO_INITIALIZED)
  195 
  196 /*
  197  * Helpful macros for quickly coming up with assertions with informative
  198  * panic messages.
  199  */
  200 #define MPASS(ex)               MPASS4(ex, #ex, __FILE__, __LINE__)
  201 #define MPASS2(ex, what)        MPASS4(ex, what, __FILE__, __LINE__)
  202 #define MPASS3(ex, file, line)  MPASS4(ex, #ex, file, line)
  203 #define MPASS4(ex, what, file, line)                                    \
  204         KASSERT((ex), ("Assertion %s failed at %s:%d", what, file, line))
  205 
  206 extern struct lock_class lock_class_mtx_sleep;
  207 extern struct lock_class lock_class_mtx_spin;
  208 extern struct lock_class lock_class_sx;
  209 extern struct lock_class lock_class_rw;
  210 extern struct lock_class lock_class_rm;
  211 extern struct lock_class lock_class_rm_sleepable;
  212 extern struct lock_class lock_class_lockmgr;
  213 
  214 extern struct lock_class *lock_classes[];
  215 
  216 struct lock_delay_config {
  217         u_int base;
  218         u_int max;
  219 };
  220 
  221 struct lock_delay_arg {
  222         struct lock_delay_config *config;
  223         u_int delay;
  224         u_int spin_cnt;
  225 };
  226 
  227 static inline void
  228 lock_delay_arg_init(struct lock_delay_arg *la, struct lock_delay_config *lc)
  229 {
  230         la->config = lc;
  231         la->delay = lc->base;
  232         la->spin_cnt = 0;
  233 }
  234 
  235 #define lock_delay_spin(n)      do {    \
  236         u_int _i;                       \
  237                                         \
  238         for (_i = (n); _i > 0; _i--)    \
  239                 cpu_spinwait();         \
  240 } while (0)
  241 
  242 #define LOCK_DELAY_SYSINIT(func) \
  243         SYSINIT(func##_ld, SI_SUB_LOCK, SI_ORDER_ANY, func, NULL)
  244 
  245 #define LOCK_DELAY_SYSINIT_DEFAULT(lc) \
  246         SYSINIT(lock_delay_##lc##_ld, SI_SUB_LOCK, SI_ORDER_ANY, \
  247             lock_delay_default_init, &lc)
  248 
  249 void    lock_init(struct lock_object *, struct lock_class *,
  250             const char *, const char *, int);
  251 void    lock_destroy(struct lock_object *);
  252 void    lock_delay(struct lock_delay_arg *);
  253 void    lock_delay_default_init(struct lock_delay_config *);
  254 void    spinlock_enter(void);
  255 void    spinlock_exit(void);
  256 void    witness_init(struct lock_object *, const char *);
  257 void    witness_destroy(struct lock_object *);
  258 int     witness_defineorder(struct lock_object *, struct lock_object *);
  259 void    witness_checkorder(struct lock_object *, int, const char *, int,
  260             struct lock_object *);
  261 void    witness_lock(struct lock_object *, int, const char *, int);
  262 void    witness_upgrade(struct lock_object *, int, const char *, int);
  263 void    witness_downgrade(struct lock_object *, int, const char *, int);
  264 void    witness_unlock(struct lock_object *, int, const char *, int);
  265 void    witness_save(struct lock_object *, const char **, int *);
  266 void    witness_restore(struct lock_object *, const char *, int);
  267 int     witness_list_locks(struct lock_list_entry **,
  268             int (*)(const char *, ...));
  269 int     witness_warn(int, struct lock_object *, const char *, ...);
  270 void    witness_assert(const struct lock_object *, int, const char *, int);
  271 void    witness_display_spinlock(struct lock_object *, struct thread *,
  272             int (*)(const char *, ...));
  273 int     witness_line(struct lock_object *);
  274 void    witness_norelease(struct lock_object *);
  275 void    witness_releaseok(struct lock_object *);
  276 const char *witness_file(struct lock_object *);
  277 void    witness_thread_exit(struct thread *);
  278 
  279 #ifdef  WITNESS
  280 int     witness_startup_count(void);
  281 void    witness_startup(void *);
  282 
  283 /* Flags for witness_warn(). */
  284 #define WARN_GIANTOK    0x01    /* Giant is exempt from this check. */
  285 #define WARN_PANIC      0x02    /* Panic if check fails. */
  286 #define WARN_SLEEPOK    0x04    /* Sleepable locks are exempt from check. */
  287 
  288 #define WITNESS_INIT(lock, type)                                        \
  289         witness_init((lock), (type))
  290 
  291 #define WITNESS_DESTROY(lock)                                           \
  292         witness_destroy(lock)
  293 
  294 #define WITNESS_CHECKORDER(lock, flags, file, line, interlock)          \
  295         witness_checkorder((lock), (flags), (file), (line), (interlock))
  296 
  297 #define WITNESS_DEFINEORDER(lock1, lock2)                               \
  298         witness_defineorder((struct lock_object *)(lock1),              \
  299             (struct lock_object *)(lock2))
  300 
  301 #define WITNESS_LOCK(lock, flags, file, line)                           \
  302         witness_lock((lock), (flags), (file), (line))
  303 
  304 #define WITNESS_UPGRADE(lock, flags, file, line)                        \
  305         witness_upgrade((lock), (flags), (file), (line))
  306 
  307 #define WITNESS_DOWNGRADE(lock, flags, file, line)                      \
  308         witness_downgrade((lock), (flags), (file), (line))
  309 
  310 #define WITNESS_UNLOCK(lock, flags, file, line)                         \
  311         witness_unlock((lock), (flags), (file), (line))
  312 
  313 #define WITNESS_CHECK(flags, lock, fmt, ...)                            \
  314         witness_warn((flags), (lock), (fmt), ## __VA_ARGS__)
  315 
  316 #define WITNESS_WARN(flags, lock, fmt, ...)                             \
  317         witness_warn((flags), (lock), (fmt), ## __VA_ARGS__)
  318 
  319 #define WITNESS_SAVE_DECL(n)                                            \
  320         const char * __CONCAT(n, __wf);                                 \
  321         int __CONCAT(n, __wl)
  322 
  323 #define WITNESS_SAVE(lock, n)                                           \
  324         witness_save((lock), &__CONCAT(n, __wf), &__CONCAT(n, __wl))
  325 
  326 #define WITNESS_RESTORE(lock, n)                                        \
  327         witness_restore((lock), __CONCAT(n, __wf), __CONCAT(n, __wl))
  328 
  329 #define WITNESS_NORELEASE(lock)                                         \
  330         witness_norelease(&(lock)->lock_object)
  331 
  332 #define WITNESS_RELEASEOK(lock)                                         \
  333         witness_releaseok(&(lock)->lock_object)
  334 
  335 #define WITNESS_FILE(lock)                                              \
  336         witness_file(lock)
  337 
  338 #define WITNESS_LINE(lock)                                              \
  339         witness_line(lock)
  340 
  341 #else   /* WITNESS */
  342 #define WITNESS_INIT(lock, type)                                (void)0
  343 #define WITNESS_DESTROY(lock)                                   (void)0
  344 #define WITNESS_DEFINEORDER(lock1, lock2)       0
  345 #define WITNESS_CHECKORDER(lock, flags, file, line, interlock)  (void)0
  346 #define WITNESS_LOCK(lock, flags, file, line)                   (void)0
  347 #define WITNESS_UPGRADE(lock, flags, file, line)                (void)0
  348 #define WITNESS_DOWNGRADE(lock, flags, file, line)              (void)0
  349 #define WITNESS_UNLOCK(lock, flags, file, line)                 (void)0
  350 #define WITNESS_CHECK(flags, lock, fmt, ...)    0
  351 #define WITNESS_WARN(flags, lock, fmt, ...)                     (void)0
  352 #define WITNESS_SAVE_DECL(n)                                    (void)0
  353 #define WITNESS_SAVE(lock, n)                                   (void)0
  354 #define WITNESS_RESTORE(lock, n)                                (void)0
  355 #define WITNESS_NORELEASE(lock)                                 (void)0
  356 #define WITNESS_RELEASEOK(lock)                                 (void)0
  357 #define WITNESS_FILE(lock) ("?")
  358 #define WITNESS_LINE(lock) (0)
  359 #endif  /* WITNESS */
  360 
  361 #endif  /* _KERNEL */
  362 #endif  /* _SYS_LOCK_H_ */

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