The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/sys/mutex.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: releng/8.0/sys/sys/mutex.h 194578 2009-06-21 09:01:12Z rdivacky $
   30  */
   31 
   32 #ifndef _SYS_MUTEX_H_
   33 #define _SYS_MUTEX_H_
   34 
   35 #ifndef LOCORE
   36 #include <sys/queue.h>
   37 #include <sys/_lock.h>
   38 #include <sys/_mutex.h>
   39 
   40 #ifdef _KERNEL
   41 #include <sys/pcpu.h>
   42 #include <sys/lock_profile.h>
   43 #include <sys/lockstat.h>
   44 #include <machine/atomic.h>
   45 #include <machine/cpufunc.h>
   46 #endif  /* _KERNEL_ */
   47 #endif  /* !LOCORE */
   48 
   49 #include <machine/mutex.h>
   50 
   51 #ifdef _KERNEL
   52 
   53 /*
   54  * Mutex types and options passed to mtx_init().  MTX_QUIET and MTX_DUPOK
   55  * can also be passed in.
   56  */
   57 #define MTX_DEF         0x00000000      /* DEFAULT (sleep) lock */ 
   58 #define MTX_SPIN        0x00000001      /* Spin lock (disables interrupts) */
   59 #define MTX_RECURSE     0x00000004      /* Option: lock allowed to recurse */
   60 #define MTX_NOWITNESS   0x00000008      /* Don't do any witness checking. */
   61 #define MTX_NOPROFILE   0x00000020      /* Don't profile this lock */
   62 
   63 /*
   64  * Option flags passed to certain lock/unlock routines, through the use
   65  * of corresponding mtx_{lock,unlock}_flags() interface macros.
   66  */
   67 #define MTX_QUIET       LOP_QUIET       /* Don't log a mutex event */
   68 #define MTX_DUPOK       LOP_DUPOK       /* Don't log a duplicate acquire */
   69 
   70 /*
   71  * State bits kept in mutex->mtx_lock, for the DEFAULT lock type. None of this,
   72  * with the exception of MTX_UNOWNED, applies to spin locks.
   73  */
   74 #define MTX_RECURSED    0x00000001      /* lock recursed (for MTX_DEF only) */
   75 #define MTX_CONTESTED   0x00000002      /* lock contested (for MTX_DEF only) */
   76 #define MTX_UNOWNED     0x00000004      /* Cookie for free mutex */
   77 #define MTX_FLAGMASK    (MTX_RECURSED | MTX_CONTESTED | MTX_UNOWNED)
   78 
   79 /*
   80  * Value stored in mutex->mtx_lock to denote a destroyed mutex.
   81  */
   82 #define MTX_DESTROYED   (MTX_CONTESTED | MTX_UNOWNED)
   83 
   84 #endif  /* _KERNEL */
   85 
   86 #ifndef LOCORE
   87 
   88 /*
   89  * XXX: Friendly reminder to fix things in MP code that is presently being
   90  * XXX: worked on.
   91  */
   92 #define mp_fixme(string)
   93 
   94 #ifdef _KERNEL
   95 
   96 /*
   97  * Prototypes
   98  *
   99  * NOTE: Functions prepended with `_' (underscore) are exported to other parts
  100  *       of the kernel via macros, thus allowing us to use the cpp LOCK_FILE
  101  *       and LOCK_LINE. These functions should not be called directly by any
  102  *       code using the API. Their macros cover their functionality.
  103  *
  104  * [See below for descriptions]
  105  *
  106  */
  107 void    mtx_init(struct mtx *m, const char *name, const char *type, int opts);
  108 void    mtx_destroy(struct mtx *m);
  109 void    mtx_sysinit(void *arg);
  110 void    mutex_init(void);
  111 void    _mtx_lock_sleep(struct mtx *m, uintptr_t tid, int opts,
  112             const char *file, int line);
  113 void    _mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line);
  114 #ifdef SMP
  115 void    _mtx_lock_spin(struct mtx *m, uintptr_t tid, int opts,
  116             const char *file, int line);
  117 #endif
  118 void    _mtx_unlock_spin(struct mtx *m, int opts, const char *file, int line);
  119 int     _mtx_trylock(struct mtx *m, int opts, const char *file, int line);
  120 void    _mtx_lock_flags(struct mtx *m, int opts, const char *file, int line);
  121 void    _mtx_unlock_flags(struct mtx *m, int opts, const char *file, int line);
  122 void    _mtx_lock_spin_flags(struct mtx *m, int opts, const char *file,
  123              int line);
  124 void    _mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file,
  125              int line);
  126 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT)
  127 void    _mtx_assert(struct mtx *m, int what, const char *file, int line);
  128 #endif
  129 void    _thread_lock_flags(struct thread *, int, const char *, int);
  130 
  131 #define thread_lock(tdp)                                                \
  132     _thread_lock_flags((tdp), 0, __FILE__, __LINE__)
  133 #define thread_lock_flags(tdp, opt)                                     \
  134     _thread_lock_flags((tdp), (opt), __FILE__, __LINE__)
  135 #define thread_unlock(tdp)                                              \
  136        mtx_unlock_spin((tdp)->td_lock)
  137 
  138 #define mtx_recurse     lock_object.lo_data
  139 
  140 /*
  141  * We define our machine-independent (unoptimized) mutex micro-operations
  142  * here, if they are not already defined in the machine-dependent mutex.h 
  143  */
  144 
  145 /* Try to obtain mtx_lock once. */
  146 #ifndef _obtain_lock
  147 #define _obtain_lock(mp, tid)                                           \
  148         atomic_cmpset_acq_ptr(&(mp)->mtx_lock, MTX_UNOWNED, (tid))
  149 #endif
  150 
  151 /* Try to release mtx_lock if it is unrecursed and uncontested. */
  152 #ifndef _release_lock
  153 #define _release_lock(mp, tid)                                          \
  154         atomic_cmpset_rel_ptr(&(mp)->mtx_lock, (tid), MTX_UNOWNED)
  155 #endif
  156 
  157 /* Release mtx_lock quickly, assuming we own it. */
  158 #ifndef _release_lock_quick
  159 #define _release_lock_quick(mp)                                         \
  160         atomic_store_rel_ptr(&(mp)->mtx_lock, MTX_UNOWNED)
  161 #endif
  162 
  163 /*
  164  * Obtain a sleep lock inline, or call the "hard" function if we can't get it
  165  * easy.
  166  */
  167 #ifndef _get_sleep_lock
  168 #define _get_sleep_lock(mp, tid, opts, file, line) do {                 \
  169         uintptr_t _tid = (uintptr_t)(tid);                              \
  170         if (!_obtain_lock((mp), _tid))                                  \
  171                 _mtx_lock_sleep((mp), _tid, (opts), (file), (line));    \
  172         else                                                            \
  173                 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_LOCK_ACQUIRE, \
  174                     mp, 0, 0, (file), (line));                          \
  175 } while (0)
  176 #endif
  177 
  178 /*
  179  * Obtain a spin lock inline, or call the "hard" function if we can't get it
  180  * easy. For spinlocks, we handle recursion inline (it turns out that function
  181  * calls can be significantly expensive on some architectures).
  182  * Since spin locks are not _too_ common, inlining this code is not too big 
  183  * a deal.
  184  */
  185 #ifndef _get_spin_lock
  186 #ifdef SMP
  187 #define _get_spin_lock(mp, tid, opts, file, line) do {  \
  188         uintptr_t _tid = (uintptr_t)(tid);                              \
  189         spinlock_enter();                                               \
  190         if (!_obtain_lock((mp), _tid)) {                                \
  191                 if ((mp)->mtx_lock == _tid)                             \
  192                         (mp)->mtx_recurse++;                            \
  193                 else {                                                  \
  194                         _mtx_lock_spin((mp), _tid, (opts), (file), (line)); \
  195                 }                                                       \
  196         } else                                                          \
  197                 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_SPIN_LOCK_ACQUIRE, \
  198                     mp, 0, 0, (file), (line));                          \
  199 } while (0)
  200 #else /* SMP */
  201 #define _get_spin_lock(mp, tid, opts, file, line) do {                  \
  202         uintptr_t _tid = (uintptr_t)(tid);                              \
  203                                                                         \
  204         spinlock_enter();                                               \
  205         if ((mp)->mtx_lock == _tid)                                     \
  206                 (mp)->mtx_recurse++;                                    \
  207         else {                                                          \
  208                 KASSERT((mp)->mtx_lock == MTX_UNOWNED, ("corrupt spinlock")); \
  209                 (mp)->mtx_lock = _tid;                          \
  210         }                                                               \
  211 } while (0)
  212 #endif /* SMP */
  213 #endif
  214 
  215 /*
  216  * Release a sleep lock inline, or call the "hard" function if we can't do it
  217  * easy.
  218  */
  219 #ifndef _rel_sleep_lock
  220 #define _rel_sleep_lock(mp, tid, opts, file, line) do {                 \
  221         uintptr_t _tid = (uintptr_t)(tid);                              \
  222                                                                         \
  223         if (!_release_lock((mp), _tid))                                 \
  224                 _mtx_unlock_sleep((mp), (opts), (file), (line));        \
  225 } while (0)
  226 #endif
  227 
  228 /*
  229  * For spinlocks, we can handle everything inline, as it's pretty simple and
  230  * a function call would be too expensive (at least on some architectures).
  231  * Since spin locks are not _too_ common, inlining this code is not too big 
  232  * a deal.
  233  *
  234  * Since we always perform a spinlock_enter() when attempting to acquire a
  235  * spin lock, we need to always perform a matching spinlock_exit() when
  236  * releasing a spin lock.  This includes the recursion cases.
  237  */
  238 #ifndef _rel_spin_lock
  239 #ifdef SMP
  240 #define _rel_spin_lock(mp) do {                                         \
  241         if (mtx_recursed((mp)))                                         \
  242                 (mp)->mtx_recurse--;                                    \
  243         else {                                                          \
  244                 LOCKSTAT_PROFILE_RELEASE_LOCK(LS_MTX_SPIN_UNLOCK_RELEASE, \
  245                         mp);                                            \
  246                 _release_lock_quick((mp));                              \
  247         }                                                               \
  248         spinlock_exit();                                                \
  249 } while (0)
  250 #else /* SMP */
  251 #define _rel_spin_lock(mp) do {                                         \
  252         if (mtx_recursed((mp)))                                         \
  253                 (mp)->mtx_recurse--;                                    \
  254         else                                                            \
  255                 (mp)->mtx_lock = MTX_UNOWNED;                           \
  256         spinlock_exit();                                                \
  257 } while (0)
  258 #endif /* SMP */
  259 #endif
  260 
  261 /*
  262  * Exported lock manipulation interface.
  263  *
  264  * mtx_lock(m) locks MTX_DEF mutex `m'
  265  *
  266  * mtx_lock_spin(m) locks MTX_SPIN mutex `m'
  267  *
  268  * mtx_unlock(m) unlocks MTX_DEF mutex `m'
  269  *
  270  * mtx_unlock_spin(m) unlocks MTX_SPIN mutex `m'
  271  *
  272  * mtx_lock_spin_flags(m, opts) and mtx_lock_flags(m, opts) locks mutex `m'
  273  *     and passes option flags `opts' to the "hard" function, if required.
  274  *     With these routines, it is possible to pass flags such as MTX_QUIET
  275  *     to the appropriate lock manipulation routines.
  276  *
  277  * mtx_trylock(m) attempts to acquire MTX_DEF mutex `m' but doesn't sleep if
  278  *     it cannot. Rather, it returns 0 on failure and non-zero on success.
  279  *     It does NOT handle recursion as we assume that if a caller is properly
  280  *     using this part of the interface, he will know that the lock in question
  281  *     is _not_ recursed.
  282  *
  283  * mtx_trylock_flags(m, opts) is used the same way as mtx_trylock() but accepts
  284  *     relevant option flags `opts.'
  285  *
  286  * mtx_initialized(m) returns non-zero if the lock `m' has been initialized.
  287  *
  288  * mtx_owned(m) returns non-zero if the current thread owns the lock `m'
  289  *
  290  * mtx_recursed(m) returns non-zero if the lock `m' is presently recursed.
  291  */ 
  292 #define mtx_lock(m)             mtx_lock_flags((m), 0)
  293 #define mtx_lock_spin(m)        mtx_lock_spin_flags((m), 0)
  294 #define mtx_trylock(m)          mtx_trylock_flags((m), 0)
  295 #define mtx_unlock(m)           mtx_unlock_flags((m), 0)
  296 #define mtx_unlock_spin(m)      mtx_unlock_spin_flags((m), 0)
  297 
  298 struct mtx_pool;
  299 
  300 struct mtx_pool *mtx_pool_create(const char *mtx_name, int pool_size, int opts);
  301 void mtx_pool_destroy(struct mtx_pool **poolp);
  302 struct mtx *mtx_pool_find(struct mtx_pool *pool, void *ptr);
  303 struct mtx *mtx_pool_alloc(struct mtx_pool *pool);
  304 #define mtx_pool_lock(pool, ptr)                                        \
  305         mtx_lock(mtx_pool_find((pool), (ptr)))
  306 #define mtx_pool_lock_spin(pool, ptr)                                   \
  307         mtx_lock_spin(mtx_pool_find((pool), (ptr)))
  308 #define mtx_pool_unlock(pool, ptr)                                      \
  309         mtx_unlock(mtx_pool_find((pool), (ptr)))
  310 #define mtx_pool_unlock_spin(pool, ptr)                                 \
  311         mtx_unlock_spin(mtx_pool_find((pool), (ptr)))
  312 
  313 /*
  314  * mtxpool_lockbuilder is a pool of sleep locks that is not witness
  315  * checked and should only be used for building higher level locks.
  316  *
  317  * mtxpool_sleep is a general purpose pool of sleep mutexes.
  318  */
  319 extern struct mtx_pool *mtxpool_lockbuilder;
  320 extern struct mtx_pool *mtxpool_sleep;
  321 
  322 #ifndef LOCK_DEBUG
  323 #error LOCK_DEBUG not defined, include <sys/lock.h> before <sys/mutex.h>
  324 #endif
  325 #if LOCK_DEBUG > 0 || defined(MUTEX_NOINLINE)
  326 #define mtx_lock_flags(m, opts)                                         \
  327         _mtx_lock_flags((m), (opts), LOCK_FILE, LOCK_LINE)
  328 #define mtx_unlock_flags(m, opts)                                       \
  329         _mtx_unlock_flags((m), (opts), LOCK_FILE, LOCK_LINE)
  330 #define mtx_lock_spin_flags(m, opts)                                    \
  331         _mtx_lock_spin_flags((m), (opts), LOCK_FILE, LOCK_LINE)
  332 #define mtx_unlock_spin_flags(m, opts)                                  \
  333         _mtx_unlock_spin_flags((m), (opts), LOCK_FILE, LOCK_LINE)
  334 #else   /* LOCK_DEBUG == 0 && !MUTEX_NOINLINE */
  335 #define mtx_lock_flags(m, opts)                                         \
  336         _get_sleep_lock((m), curthread, (opts), LOCK_FILE, LOCK_LINE)
  337 #define mtx_unlock_flags(m, opts)                                       \
  338         _rel_sleep_lock((m), curthread, (opts), LOCK_FILE, LOCK_LINE)
  339 #define mtx_lock_spin_flags(m, opts)                                    \
  340         _get_spin_lock((m), curthread, (opts), LOCK_FILE, LOCK_LINE)
  341 #define mtx_unlock_spin_flags(m, opts)                                  \
  342         _rel_spin_lock((m))
  343 #endif  /* LOCK_DEBUG > 0 || MUTEX_NOINLINE */
  344 
  345 #define mtx_trylock_flags(m, opts)                                      \
  346         _mtx_trylock((m), (opts), LOCK_FILE, LOCK_LINE)
  347 
  348 #define mtx_sleep(chan, mtx, pri, wmesg, timo)                          \
  349         _sleep((chan), &(mtx)->lock_object, (pri), (wmesg), (timo))
  350 
  351 #define mtx_initialized(m)      lock_initalized(&(m)->lock_object)
  352 
  353 #define mtx_owned(m)    (((m)->mtx_lock & ~MTX_FLAGMASK) == (uintptr_t)curthread)
  354 
  355 #define mtx_recursed(m) ((m)->mtx_recurse != 0)
  356 
  357 #define mtx_name(m)     ((m)->lock_object.lo_name)
  358 
  359 /*
  360  * Global locks.
  361  */
  362 extern struct mtx Giant;
  363 extern struct mtx blocked_lock;
  364 
  365 /*
  366  * Giant lock manipulation and clean exit macros.
  367  * Used to replace return with an exit Giant and return.
  368  *
  369  * Note that DROP_GIANT*() needs to be paired with PICKUP_GIANT() 
  370  * The #ifndef is to allow lint-like tools to redefine DROP_GIANT.
  371  */
  372 #ifndef DROP_GIANT
  373 #define DROP_GIANT()                                                    \
  374 do {                                                                    \
  375         int _giantcnt = 0;                                              \
  376         WITNESS_SAVE_DECL(Giant);                                       \
  377                                                                         \
  378         if (mtx_owned(&Giant)) {                                        \
  379                 WITNESS_SAVE(&Giant.lock_object, Giant);                \
  380                 for (_giantcnt = 0; mtx_owned(&Giant); _giantcnt++)     \
  381                         mtx_unlock(&Giant);                             \
  382         }
  383 
  384 #define PICKUP_GIANT()                                                  \
  385         PARTIAL_PICKUP_GIANT();                                         \
  386 } while (0)
  387 
  388 #define PARTIAL_PICKUP_GIANT()                                          \
  389         mtx_assert(&Giant, MA_NOTOWNED);                                \
  390         if (_giantcnt > 0) {                                            \
  391                 while (_giantcnt--)                                     \
  392                         mtx_lock(&Giant);                               \
  393                 WITNESS_RESTORE(&Giant.lock_object, Giant);             \
  394         }
  395 #endif
  396 
  397 #define UGAR(rval) do {                                                 \
  398         int _val = (rval);                                              \
  399         mtx_unlock(&Giant);                                             \
  400         return (_val);                                                  \
  401 } while (0)
  402 
  403 struct mtx_args {
  404         struct mtx      *ma_mtx;
  405         const char      *ma_desc;
  406         int              ma_opts;
  407 };
  408 
  409 #define MTX_SYSINIT(name, mtx, desc, opts)                              \
  410         static struct mtx_args name##_args = {                          \
  411                 (mtx),                                                  \
  412                 (desc),                                                 \
  413                 (opts)                                                  \
  414         };                                                              \
  415         SYSINIT(name##_mtx_sysinit, SI_SUB_LOCK, SI_ORDER_MIDDLE,       \
  416             mtx_sysinit, &name##_args);                                 \
  417         SYSUNINIT(name##_mtx_sysuninit, SI_SUB_LOCK, SI_ORDER_MIDDLE,   \
  418             mtx_destroy, (mtx))
  419 
  420 /*
  421  * The INVARIANTS-enabled mtx_assert() functionality.
  422  *
  423  * The constants need to be defined for INVARIANT_SUPPORT infrastructure
  424  * support as _mtx_assert() itself uses them and the latter implies that
  425  * _mtx_assert() must build.
  426  */
  427 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT)
  428 #define MA_OWNED        LA_XLOCKED
  429 #define MA_NOTOWNED     LA_UNLOCKED
  430 #define MA_RECURSED     LA_RECURSED
  431 #define MA_NOTRECURSED  LA_NOTRECURSED
  432 #endif
  433 
  434 #ifdef INVARIANTS
  435 #define mtx_assert(m, what)                                             \
  436         _mtx_assert((m), (what), __FILE__, __LINE__)
  437 
  438 #define GIANT_REQUIRED  mtx_assert(&Giant, MA_OWNED)
  439 
  440 #else   /* INVARIANTS */
  441 #define mtx_assert(m, what)     (void)0
  442 #define GIANT_REQUIRED
  443 #endif  /* INVARIANTS */
  444 
  445 /*
  446  * Common lock type names.
  447  */
  448 #define MTX_NETWORK_LOCK        "network driver"
  449 
  450 #endif  /* _KERNEL */
  451 #endif  /* !LOCORE */
  452 #endif  /* _SYS_MUTEX_H_ */

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