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  * 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 Exp $
   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 thread;
   39 
   40 /*
   41  * Lock classes.  Each lock has a class which describes characteristics
   42  * common to all types of locks of a given class.
   43  *
   44  * Spin locks in general must always protect against preemption, as it is
   45  * an error to perform any type of context switch while holding a spin lock.
   46  * Also, for an individual lock to be recursable, its class must allow
   47  * recursion and the lock itself must explicitly allow recursion.
   48  *
   49  * The 'lc_ddb_show' function pointer is used to dump class-specific
   50  * data for the 'show lock' DDB command.  The 'lc_lock' and
   51  * 'lc_unlock' function pointers are used in sleep(9) and cv_wait(9)
   52  * to lock and unlock locks while blocking on a sleep queue.  The
   53  * return value of 'lc_unlock' will be passed to 'lc_lock' on resume
   54  * to allow communication of state between the two routines.
   55  */
   56 
   57 struct lock_class {
   58         const   char *lc_name;
   59         u_int   lc_flags;
   60         void    (*lc_ddb_show)(struct lock_object *lock);
   61         void    (*lc_lock)(struct lock_object *lock, int how);
   62         int     (*lc_unlock)(struct lock_object *lock);
   63 };
   64 
   65 #define LC_SLEEPLOCK    0x00000001      /* Sleep lock. */
   66 #define LC_SPINLOCK     0x00000002      /* Spin lock. */
   67 #define LC_SLEEPABLE    0x00000004      /* Sleeping allowed with this lock. */
   68 #define LC_RECURSABLE   0x00000008      /* Locks of this type may recurse. */
   69 #define LC_UPGRADABLE   0x00000010      /* Upgrades and downgrades permitted. */
   70 
   71 #define LO_CLASSFLAGS   0x0000ffff      /* Class specific flags. */
   72 #define LO_INITIALIZED  0x00010000      /* Lock has been initialized. */
   73 #define LO_WITNESS      0x00020000      /* Should witness monitor this lock. */
   74 #define LO_QUIET        0x00040000      /* Don't log locking operations. */
   75 #define LO_RECURSABLE   0x00080000      /* Lock may recurse. */
   76 #define LO_SLEEPABLE    0x00100000      /* Lock may be held while sleeping. */
   77 #define LO_UPGRADABLE   0x00200000      /* Lock may be upgraded/downgraded. */
   78 #define LO_DUPOK        0x00400000      /* Don't check for duplicate acquires */
   79 #define LO_ENROLLPEND   0x00800000      /* On the pending enroll list. */
   80 #define LO_CLASSMASK    0x0f000000      /* Class index bitmask. */
   81 #define LO_NOPROFILE    0x10000000      /* Don't profile this lock */
   82 
   83 /*
   84  * Lock classes are statically assigned an index into the gobal lock_classes
   85  * array.  Debugging code looks up the lock class for a given lock object
   86  * by indexing the array.
   87  */
   88 #define LO_CLASSSHIFT           24
   89 #define LO_CLASSINDEX(lock)     ((((lock)->lo_flags) & LO_CLASSMASK) >> LO_CLASSSHIFT)
   90 #define LOCK_CLASS(lock)        (lock_classes[LO_CLASSINDEX((lock))])
   91 #define LOCK_CLASS_MAX          (LO_CLASSMASK >> LO_CLASSSHIFT)
   92 
   93 #define LI_RECURSEMASK  0x0000ffff      /* Recursion depth of lock instance. */
   94 #define LI_EXCLUSIVE    0x00010000      /* Exclusive lock instance. */
   95 
   96 /*
   97  * Option flags passed to lock operations that witness also needs to know
   98  * about or that are generic across all locks.
   99  */
  100 #define LOP_NEWORDER    0x00000001      /* Define a new lock order. */
  101 #define LOP_QUIET       0x00000002      /* Don't log locking operations. */
  102 #define LOP_TRYLOCK     0x00000004      /* Don't check lock order. */
  103 #define LOP_EXCLUSIVE   0x00000008      /* Exclusive lock. */
  104 #define LOP_DUPOK       0x00000010      /* Don't check for duplicate acquires */
  105 
  106 /* Flags passed to witness_assert. */
  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  * Lock instances.  A lock instance is the data associated with a lock while
  117  * it is held by witness.  For example, a lock instance will hold the
  118  * recursion count of a lock.  Lock instances are held in lists.  Spin locks
  119  * are held in a per-cpu list while sleep locks are held in per-thread list.
  120  */
  121 struct lock_instance {
  122         struct  lock_object *li_lock;
  123         const   char *li_file;          /* File and line of last acquire. */
  124         int     li_line;
  125         u_int   li_flags;               /* Recursion count and LI_* flags. */
  126 };
  127 
  128 /*
  129  * A simple list type used to build the list of locks held by a thread
  130  * or CPU.  We can't simply embed the list in struct lock_object since a
  131  * lock may be held by more than one thread if it is a shared lock.  Locks
  132  * are added to the head of the list, so we fill up each list entry from
  133  * "the back" logically.  To ease some of the arithmetic, we actually fill
  134  * in each list entry the normal way (childer[0] then children[1], etc.) but
  135  * when we traverse the list we read children[count-1] as the first entry
  136  * down to children[0] as the final entry.
  137  */
  138 #define LOCK_NCHILDREN  3
  139 
  140 struct lock_list_entry {
  141         struct  lock_list_entry *ll_next;
  142         struct  lock_instance ll_children[LOCK_NCHILDREN];
  143         u_int   ll_count;
  144 };
  145 
  146 /*
  147  * If any of WITNESS, INVARIANTS, or KTR_LOCK KTR tracing has been enabled,
  148  * then turn on LOCK_DEBUG.  When this option is on, extra debugging
  149  * facilities such as tracking the file and line number of lock operations
  150  * are enabled.  Also, mutex locking operations are not inlined to avoid
  151  * bloat from all the extra debugging code.  We also have to turn on all the
  152  * calling conventions for this debugging code in modules so that modules can
  153  * work with both debug and non-debug kernels.
  154  */
  155 #if defined(KLD_MODULE) || defined(WITNESS) || defined(INVARIANTS) || defined(INVARIANT_SUPPORT) || defined(KTR) || defined(LOCK_PROFILING)
  156 #define LOCK_DEBUG      1
  157 #else
  158 #define LOCK_DEBUG      0
  159 #endif
  160 
  161 /*
  162  * In the LOCK_DEBUG case, use the filename and line numbers for debugging
  163  * operations.  Otherwise, use default values to avoid the unneeded bloat.
  164  */
  165 #if LOCK_DEBUG > 0
  166 #define LOCK_FILE       __FILE__
  167 #define LOCK_LINE       __LINE__
  168 #else
  169 #define LOCK_FILE       NULL
  170 #define LOCK_LINE       0
  171 #endif
  172 
  173 /*
  174  * Macros for KTR_LOCK tracing.
  175  *
  176  * opname  - name of this operation (LOCK/UNLOCK/SLOCK, etc.)
  177  * lo      - struct lock_object * for this lock
  178  * flags   - flags passed to the lock operation
  179  * recurse - this locks recursion level (or 0 if class is not recursable)
  180  * result  - result of a try lock operation
  181  * file    - file name
  182  * line    - line number
  183  */
  184 #define LOCK_LOG_TEST(lo, flags)                                        \
  185         (((flags) & LOP_QUIET) == 0 && ((lo)->lo_flags & LO_QUIET) == 0)
  186 
  187 #define LOCK_LOG_LOCK(opname, lo, flags, recurse, file, line) do {      \
  188         if (LOCK_LOG_TEST((lo), (flags)))                               \
  189                 CTR5(KTR_LOCK, opname " (%s) %s r = %d at %s:%d",       \
  190                     LOCK_CLASS(lo)->lc_name, (lo)->lo_name,             \
  191                     (u_int)(recurse), (file), (line));                  \
  192 } while (0)
  193 
  194 #define LOCK_LOG_TRY(opname, lo, flags, result, file, line) do {        \
  195         if (LOCK_LOG_TEST((lo), (flags)))                               \
  196                 CTR5(KTR_LOCK, "TRY_" opname " (%s) %s result=%d at %s:%d",\
  197                     LOCK_CLASS(lo)->lc_name, (lo)->lo_name,             \
  198                     (u_int)(result), (file), (line));                   \
  199 } while (0)
  200 
  201 #define LOCK_LOG_INIT(lo, flags) do {                                   \
  202         if (LOCK_LOG_TEST((lo), (flags)))                               \
  203                 CTR4(KTR_LOCK, "%s: %p (%s) %s", __func__, (lo),        \
  204                     LOCK_CLASS(lo)->lc_name, (lo)->lo_name);            \
  205 } while (0)
  206 
  207 #define LOCK_LOG_DESTROY(lo, flags)     LOCK_LOG_INIT(lo, flags)
  208 
  209 #define lock_initalized(lo)     ((lo)->lo_flags & LO_INITIALIZED)
  210 
  211 /*
  212  * Helpful macros for quickly coming up with assertions with informative
  213  * panic messages.
  214  */
  215 #define MPASS(ex)               MPASS4(ex, #ex, __FILE__, __LINE__)
  216 #define MPASS2(ex, what)        MPASS4(ex, what, __FILE__, __LINE__)
  217 #define MPASS3(ex, file, line)  MPASS4(ex, #ex, file, line)
  218 #define MPASS4(ex, what, file, line)                                    \
  219         KASSERT((ex), ("Assertion %s failed at %s:%d", what, file, line))
  220 
  221 extern struct lock_class lock_class_mtx_sleep;
  222 extern struct lock_class lock_class_mtx_spin;
  223 extern struct lock_class lock_class_sx;
  224 extern struct lock_class lock_class_rw;
  225 extern struct lock_class lock_class_lockmgr;
  226 
  227 extern struct lock_class *lock_classes[];
  228 
  229 void    lock_init(struct lock_object *, struct lock_class *,
  230     const char *, const char *, int);
  231 void    lock_destroy(struct lock_object *);
  232 void    spinlock_enter(void);
  233 void    spinlock_exit(void);
  234 void    witness_init(struct lock_object *);
  235 void    witness_destroy(struct lock_object *);
  236 int     witness_defineorder(struct lock_object *, struct lock_object *);
  237 void    witness_checkorder(struct lock_object *, int, const char *, int);
  238 void    witness_lock(struct lock_object *, int, const char *, int);
  239 void    witness_upgrade(struct lock_object *, int, const char *, int);
  240 void    witness_downgrade(struct lock_object *, int, const char *, int);
  241 void    witness_unlock(struct lock_object *, int, const char *, int);
  242 void    witness_save(struct lock_object *, const char **, int *);
  243 void    witness_restore(struct lock_object *, const char *, int);
  244 int     witness_list_locks(struct lock_list_entry **);
  245 int     witness_warn(int, struct lock_object *, const char *, ...);
  246 void    witness_assert(struct lock_object *, int, const char *, int);
  247 void    witness_display_spinlock(struct lock_object *, struct thread *);
  248 int     witness_line(struct lock_object *);
  249 const char *witness_file(struct lock_object *);
  250 
  251 #ifdef  WITNESS
  252 
  253 /* Flags for witness_warn(). */
  254 #define WARN_GIANTOK    0x01    /* Giant is exempt from this check. */
  255 #define WARN_PANIC      0x02    /* Panic if check fails. */
  256 #define WARN_SLEEPOK    0x04    /* Sleepable locks are exempt from check. */
  257 
  258 #define WITNESS_INIT(lock)                                              \
  259         witness_init((lock))
  260 
  261 #define WITNESS_DESTROY(lock)                                           \
  262         witness_destroy(lock)
  263 
  264 #define WITNESS_CHECKORDER(lock, flags, file, line)                     \
  265         witness_checkorder((lock), (flags), (file), (line))
  266 
  267 #define WITNESS_DEFINEORDER(lock1, lock2)                               \
  268         witness_defineorder((struct lock_object *)(lock1),              \
  269             (struct lock_object *)(lock2))
  270 
  271 #define WITNESS_LOCK(lock, flags, file, line)                           \
  272         witness_lock((lock), (flags), (file), (line))
  273 
  274 #define WITNESS_UPGRADE(lock, flags, file, line)                        \
  275         witness_upgrade((lock), (flags), (file), (line))
  276 
  277 #define WITNESS_DOWNGRADE(lock, flags, file, line)                      \
  278         witness_downgrade((lock), (flags), (file), (line))
  279 
  280 #define WITNESS_UNLOCK(lock, flags, file, line)                         \
  281         witness_unlock((lock), (flags), (file), (line))
  282 
  283 #define WITNESS_CHECK(flags, lock, fmt, ...)                            \
  284         witness_warn((flags), (lock), (fmt), ## __VA_ARGS__)
  285 
  286 #define WITNESS_WARN(flags, lock, fmt, ...)                             \
  287         witness_warn((flags), (lock), (fmt), ## __VA_ARGS__)
  288 
  289 #define WITNESS_SAVE_DECL(n)                                            \
  290         const char * __CONCAT(n, __wf);                                 \
  291         int __CONCAT(n, __wl)
  292 
  293 #define WITNESS_SAVE(lock, n)                                           \
  294         witness_save((lock), &__CONCAT(n, __wf), &__CONCAT(n, __wl))
  295 
  296 #define WITNESS_RESTORE(lock, n)                                        \
  297         witness_restore((lock), __CONCAT(n, __wf), __CONCAT(n, __wl))
  298 
  299 #define WITNESS_FILE(lock)                                              \
  300         witness_file(lock)
  301 
  302 #define WITNESS_LINE(lock)                                              \
  303         witness_line(lock)
  304 
  305 #else   /* WITNESS */
  306 #define WITNESS_INIT(lock)
  307 #define WITNESS_DESTROY(lock)
  308 #define WITNESS_DEFINEORDER(lock1, lock2)       0
  309 #define WITNESS_CHECKORDER(lock, flags, file, line)
  310 #define WITNESS_LOCK(lock, flags, file, line)
  311 #define WITNESS_UPGRADE(lock, flags, file, line)
  312 #define WITNESS_DOWNGRADE(lock, flags, file, line)
  313 #define WITNESS_UNLOCK(lock, flags, file, line)
  314 #define WITNESS_CHECK(flags, lock, fmt, ...)    0
  315 #define WITNESS_WARN(flags, lock, fmt, ...)
  316 #define WITNESS_SAVE_DECL(n)
  317 #define WITNESS_SAVE(lock, n)
  318 #define WITNESS_RESTORE(lock, n)
  319 #define WITNESS_FILE(lock) ("?")
  320 #define WITNESS_LINE(lock) (0)
  321 #endif  /* WITNESS */
  322 
  323 /*
  324  * Helper macros to allow developers to add explicit lock order checks
  325  * wherever they please without having to actually grab a lock to do so.
  326  */
  327 #define witness_check(l)                                                \
  328         WITNESS_CHECKORDER(&(l)->lock_object, LOP_EXCLUSIVE, LOCK_FILE, \
  329             LOCK_LINE)
  330 
  331 #define witness_check_shared(l)                                         \
  332         WITNESS_CHECKORDER(&(l)->lock_object, 0, LOCK_FILE, LOCK_LINE)
  333         
  334 #endif  /* _KERNEL */
  335 #endif  /* _SYS_LOCK_H_ */

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