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/7.4/sys/sys/mutex.h 213724 2010-10-12 15:48:27Z jhb $
   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 <machine/atomic.h>
   44 #include <machine/cpufunc.h>
   45 #endif  /* _KERNEL_ */
   46 #endif  /* !LOCORE */
   47 
   48 #include <machine/mutex.h>
   49 
   50 #ifdef _KERNEL
   51 
   52 /*
   53  * Mutex types and options passed to mtx_init().  MTX_QUIET and MTX_DUPOK
   54  * can also be passed in.
   55  */
   56 #define MTX_DEF         0x00000000      /* DEFAULT (sleep) lock */ 
   57 #define MTX_SPIN        0x00000001      /* Spin lock (disables interrupts) */
   58 #define MTX_RECURSE     0x00000004      /* Option: lock allowed to recurse */
   59 #define MTX_NOWITNESS   0x00000008      /* Don't do any witness checking. */
   60 #define MTX_NOPROFILE   0x00000020      /* Don't profile this lock */
   61 
   62 /*
   63  * Option flags passed to certain lock/unlock routines, through the use
   64  * of corresponding mtx_{lock,unlock}_flags() interface macros.
   65  */
   66 #define MTX_QUIET       LOP_QUIET       /* Don't log a mutex event */
   67 #define MTX_DUPOK       LOP_DUPOK       /* Don't log a duplicate acquire */
   68 
   69 /*
   70  * State bits kept in mutex->mtx_lock, for the DEFAULT lock type. None of this,
   71  * with the exception of MTX_UNOWNED, applies to spin locks.
   72  */
   73 #define MTX_RECURSED    0x00000001      /* lock recursed (for MTX_DEF only) */
   74 #define MTX_CONTESTED   0x00000002      /* lock contested (for MTX_DEF only) */
   75 #define MTX_UNOWNED     0x00000004      /* Cookie for free mutex */
   76 #define MTX_FLAGMASK    (MTX_RECURSED | MTX_CONTESTED | MTX_UNOWNED)
   77 
   78 /*
   79  * Value stored in mutex->mtx_lock to denote a destroyed mutex.
   80  */
   81 #define MTX_DESTROYED   (MTX_CONTESTED | MTX_UNOWNED)
   82 
   83 #endif  /* _KERNEL */
   84 
   85 #ifndef LOCORE
   86 
   87 /*
   88  * XXX: Friendly reminder to fix things in MP code that is presently being
   89  * XXX: worked on.
   90  */
   91 #define mp_fixme(string)
   92 
   93 #ifdef _KERNEL
   94 
   95 /*
   96  * Prototypes
   97  *
   98  * NOTE: Functions prepended with `_' (underscore) are exported to other parts
   99  *       of the kernel via macros, thus allowing us to use the cpp LOCK_FILE
  100  *       and LOCK_LINE. These functions should not be called directly by any
  101  *       code using the API. Their macros cover their functionality.
  102  *
  103  * [See below for descriptions]
  104  *
  105  */
  106 void    mtx_init(struct mtx *m, const char *name, const char *type, int opts);
  107 void    mtx_destroy(struct mtx *m);
  108 void    mtx_sysinit(void *arg);
  109 void    mutex_init(void);
  110 void    _mtx_lock_sleep(struct mtx *m, uintptr_t tid, int opts,
  111             const char *file, int line);
  112 void    _mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line);
  113 #ifdef SMP
  114 void    _mtx_lock_spin(struct mtx *m, uintptr_t tid, int opts,
  115             const char *file, int line);
  116 #endif
  117 void    _mtx_unlock_spin(struct mtx *m, int opts, const char *file, int line);
  118 int     _mtx_trylock(struct mtx *m, int opts, const char *file, int line);
  119 void    _mtx_lock_flags(struct mtx *m, int opts, const char *file, int line);
  120 void    _mtx_unlock_flags(struct mtx *m, int opts, const char *file, int line);
  121 void    _mtx_lock_spin_flags(struct mtx *m, int opts, const char *file,
  122              int line);
  123 void    _mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file,
  124              int line);
  125 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT)
  126 void    _mtx_assert(struct mtx *m, int what, const char *file, int line);
  127 #endif
  128 void    _thread_lock_flags(struct thread *, int, const char *, int);
  129 
  130 #define thread_lock(tdp)                                                \
  131     _thread_lock_flags((tdp), 0, __FILE__, __LINE__)
  132 #define thread_lock_flags(tdp, opt)                                     \
  133     _thread_lock_flags((tdp), (opt), __FILE__, __LINE__)
  134 #define thread_unlock(tdp)                                              \
  135        mtx_unlock_spin((tdp)->td_lock)
  136 
  137 /*
  138  * We define our machine-independent (unoptimized) mutex micro-operations
  139  * here, if they are not already defined in the machine-dependent mutex.h 
  140  */
  141 
  142 /* Try to obtain mtx_lock once. */
  143 #ifndef _obtain_lock
  144 #define _obtain_lock(mp, tid)                                           \
  145         atomic_cmpset_acq_ptr(&(mp)->mtx_lock, MTX_UNOWNED, (tid))
  146 #endif
  147 
  148 /* Try to release mtx_lock if it is unrecursed and uncontested. */
  149 #ifndef _release_lock
  150 #define _release_lock(mp, tid)                                          \
  151         atomic_cmpset_rel_ptr(&(mp)->mtx_lock, (tid), MTX_UNOWNED)
  152 #endif
  153 
  154 /* Release mtx_lock quickly, assuming we own it. */
  155 #ifndef _release_lock_quick
  156 #define _release_lock_quick(mp)                                         \
  157         atomic_store_rel_ptr(&(mp)->mtx_lock, MTX_UNOWNED)
  158 #endif
  159 
  160 /*
  161  * Obtain a sleep lock inline, or call the "hard" function if we can't get it
  162  * easy.
  163  */
  164 #ifndef _get_sleep_lock
  165 #define _get_sleep_lock(mp, tid, opts, file, line) do {                 \
  166         uintptr_t _tid = (uintptr_t)(tid);                              \
  167         if (!_obtain_lock((mp), _tid)) {                                \
  168                 _mtx_lock_sleep((mp), _tid, (opts), (file), (line));    \
  169         } else                                                          \
  170                 lock_profile_obtain_lock_success(&(mp)->lock_object, 0, \
  171                     0, (file), (line));                                 \
  172 } while (0)
  173 #endif
  174 
  175 /*
  176  * Obtain a spin lock inline, or call the "hard" function if we can't get it
  177  * easy. For spinlocks, we handle recursion inline (it turns out that function
  178  * calls can be significantly expensive on some architectures).
  179  * Since spin locks are not _too_ common, inlining this code is not too big 
  180  * a deal.
  181  */
  182 #ifndef _get_spin_lock
  183 #ifdef SMP
  184 #define _get_spin_lock(mp, tid, opts, file, line) do {  \
  185         uintptr_t _tid = (uintptr_t)(tid);                              \
  186         spinlock_enter();                                               \
  187         if (!_obtain_lock((mp), _tid)) {                                \
  188                 if ((mp)->mtx_lock == _tid)                             \
  189                         (mp)->mtx_recurse++;                            \
  190                 else {                                                  \
  191                         _mtx_lock_spin((mp), _tid, (opts), (file), (line)); \
  192                 }                                                       \
  193         } else                                                          \
  194                 lock_profile_obtain_lock_success(&(mp)->lock_object, 0, \
  195                     0, (file), (line));                                 \
  196 } while (0)
  197 #else /* SMP */
  198 #define _get_spin_lock(mp, tid, opts, file, line) do {                  \
  199         uintptr_t _tid = (uintptr_t)(tid);                              \
  200                                                                         \
  201         spinlock_enter();                                               \
  202         if ((mp)->mtx_lock == _tid)                                     \
  203                 (mp)->mtx_recurse++;                                    \
  204         else {                                                          \
  205                 KASSERT((mp)->mtx_lock == MTX_UNOWNED, ("corrupt spinlock")); \
  206                 (mp)->mtx_lock = _tid;                          \
  207         }                                                               \
  208 } while (0)
  209 #endif /* SMP */
  210 #endif
  211 
  212 /*
  213  * Release a sleep lock inline, or call the "hard" function if we can't do it
  214  * easy.
  215  */
  216 #ifndef _rel_sleep_lock
  217 #define _rel_sleep_lock(mp, tid, opts, file, line) do {                 \
  218         uintptr_t _tid = (uintptr_t)(tid);                              \
  219                                                                         \
  220         if (!_release_lock((mp), _tid))                                 \
  221                 _mtx_unlock_sleep((mp), (opts), (file), (line));        \
  222 } while (0)
  223 #endif
  224 
  225 /*
  226  * For spinlocks, we can handle everything inline, as it's pretty simple and
  227  * a function call would be too expensive (at least on some architectures).
  228  * Since spin locks are not _too_ common, inlining this code is not too big 
  229  * a deal.
  230  *
  231  * Since we always perform a spinlock_enter() when attempting to acquire a
  232  * spin lock, we need to always perform a matching spinlock_exit() when
  233  * releasing a spin lock.  This includes the recursion cases.
  234  */
  235 #ifndef _rel_spin_lock
  236 #ifdef SMP
  237 #define _rel_spin_lock(mp) do {                                         \
  238         if (mtx_recursed((mp)))                                         \
  239                 (mp)->mtx_recurse--;                                    \
  240         else {                                                          \
  241                 lock_profile_release_lock(&(mp)->lock_object);          \
  242                 _release_lock_quick((mp));                              \
  243         }                                                               \
  244         spinlock_exit();                                                \
  245 } while (0)
  246 #else /* SMP */
  247 #define _rel_spin_lock(mp) do {                                         \
  248         if (mtx_recursed((mp)))                                         \
  249                 (mp)->mtx_recurse--;                                    \
  250         else {                                                          \
  251                 lock_profile_release_lock(&(mp)->lock_object);          \
  252                 (mp)->mtx_lock = MTX_UNOWNED;                           \
  253         }                                                               \
  254         spinlock_exit();                                                \
  255 } while (0)
  256 #endif /* SMP */
  257 #endif
  258 
  259 /*
  260  * Exported lock manipulation interface.
  261  *
  262  * mtx_lock(m) locks MTX_DEF mutex `m'
  263  *
  264  * mtx_lock_spin(m) locks MTX_SPIN mutex `m'
  265  *
  266  * mtx_unlock(m) unlocks MTX_DEF mutex `m'
  267  *
  268  * mtx_unlock_spin(m) unlocks MTX_SPIN mutex `m'
  269  *
  270  * mtx_lock_spin_flags(m, opts) and mtx_lock_flags(m, opts) locks mutex `m'
  271  *     and passes option flags `opts' to the "hard" function, if required.
  272  *     With these routines, it is possible to pass flags such as MTX_QUIET
  273  *     to the appropriate lock manipulation routines.
  274  *
  275  * mtx_trylock(m) attempts to acquire MTX_DEF mutex `m' but doesn't sleep if
  276  *     it cannot. Rather, it returns 0 on failure and non-zero on success.
  277  *     It does NOT handle recursion as we assume that if a caller is properly
  278  *     using this part of the interface, he will know that the lock in question
  279  *     is _not_ recursed.
  280  *
  281  * mtx_trylock_flags(m, opts) is used the same way as mtx_trylock() but accepts
  282  *     relevant option flags `opts.'
  283  *
  284  * mtx_initialized(m) returns non-zero if the lock `m' has been initialized.
  285  *
  286  * mtx_owned(m) returns non-zero if the current thread owns the lock `m'
  287  *
  288  * mtx_recursed(m) returns non-zero if the lock `m' is presently recursed.
  289  */ 
  290 #define mtx_lock(m)             mtx_lock_flags((m), 0)
  291 #define mtx_lock_spin(m)        mtx_lock_spin_flags((m), 0)
  292 #define mtx_trylock(m)          mtx_trylock_flags((m), 0)
  293 #define mtx_unlock(m)           mtx_unlock_flags((m), 0)
  294 #define mtx_unlock_spin(m)      mtx_unlock_spin_flags((m), 0)
  295 
  296 struct mtx_pool;
  297 
  298 struct mtx_pool *mtx_pool_create(const char *mtx_name, int pool_size, int opts);
  299 void mtx_pool_destroy(struct mtx_pool **poolp);
  300 struct mtx *mtx_pool_find(struct mtx_pool *pool, void *ptr);
  301 struct mtx *mtx_pool_alloc(struct mtx_pool *pool);
  302 #define mtx_pool_lock(pool, ptr)                                        \
  303         mtx_lock(mtx_pool_find((pool), (ptr)))
  304 #define mtx_pool_lock_spin(pool, ptr)                                   \
  305         mtx_lock_spin(mtx_pool_find((pool), (ptr)))
  306 #define mtx_pool_unlock(pool, ptr)                                      \
  307         mtx_unlock(mtx_pool_find((pool), (ptr)))
  308 #define mtx_pool_unlock_spin(pool, ptr)                                 \
  309         mtx_unlock_spin(mtx_pool_find((pool), (ptr)))
  310 
  311 /*
  312  * mtxpool_lockbuilder is a pool of sleep locks that is not witness
  313  * checked and should only be used for building higher level locks.
  314  *
  315  * mtxpool_sleep is a general purpose pool of sleep mutexes.
  316  */
  317 extern struct mtx_pool *mtxpool_lockbuilder;
  318 extern struct mtx_pool *mtxpool_sleep;
  319 
  320 #ifndef LOCK_DEBUG
  321 #error LOCK_DEBUG not defined, include <sys/lock.h> before <sys/mutex.h>
  322 #endif
  323 #if LOCK_DEBUG > 0 || defined(MUTEX_NOINLINE)
  324 #define mtx_lock_flags(m, opts)                                         \
  325         _mtx_lock_flags((m), (opts), LOCK_FILE, LOCK_LINE)
  326 #define mtx_unlock_flags(m, opts)                                       \
  327         _mtx_unlock_flags((m), (opts), LOCK_FILE, LOCK_LINE)
  328 #define mtx_lock_spin_flags(m, opts)                                    \
  329         _mtx_lock_spin_flags((m), (opts), LOCK_FILE, LOCK_LINE)
  330 #define mtx_unlock_spin_flags(m, opts)                                  \
  331         _mtx_unlock_spin_flags((m), (opts), LOCK_FILE, LOCK_LINE)
  332 #else   /* LOCK_DEBUG == 0 && !MUTEX_NOINLINE */
  333 #define mtx_lock_flags(m, opts)                                         \
  334         _get_sleep_lock((m), curthread, (opts), LOCK_FILE, LOCK_LINE)
  335 #define mtx_unlock_flags(m, opts)                                       \
  336         _rel_sleep_lock((m), curthread, (opts), LOCK_FILE, LOCK_LINE)
  337 #define mtx_lock_spin_flags(m, opts)                                    \
  338         _get_spin_lock((m), curthread, (opts), LOCK_FILE, LOCK_LINE)
  339 #define mtx_unlock_spin_flags(m, opts)                                  \
  340         _rel_spin_lock((m))
  341 #endif  /* LOCK_DEBUG > 0 || MUTEX_NOINLINE */
  342 
  343 #define mtx_trylock_flags(m, opts)                                      \
  344         _mtx_trylock((m), (opts), LOCK_FILE, LOCK_LINE)
  345 
  346 #define mtx_sleep(chan, mtx, pri, wmesg, timo)                          \
  347         _sleep((chan), &(mtx)->lock_object, (pri), (wmesg), (timo))
  348 
  349 #define mtx_initialized(m)      lock_initalized(&(m)->lock_object)
  350 
  351 #define mtx_owned(m)    (((m)->mtx_lock & ~MTX_FLAGMASK) == (uintptr_t)curthread)
  352 
  353 #define mtx_recursed(m) ((m)->mtx_recurse != 0)
  354 
  355 #define mtx_name(m)     ((m)->lock_object.lo_name)
  356 
  357 /*
  358  * Global locks.
  359  */
  360 extern struct mtx Giant;
  361 extern struct mtx blocked_lock;
  362 
  363 /*
  364  * Giant lock manipulation and clean exit macros.
  365  * Used to replace return with an exit Giant and return.
  366  *
  367  * Note that DROP_GIANT*() needs to be paired with PICKUP_GIANT() 
  368  * The #ifndef is to allow lint-like tools to redefine DROP_GIANT.
  369  */
  370 #ifndef DROP_GIANT
  371 #define DROP_GIANT()                                                    \
  372 do {                                                                    \
  373         int _giantcnt = 0;                                              \
  374         WITNESS_SAVE_DECL(Giant);                                       \
  375                                                                         \
  376         if (mtx_owned(&Giant)) {                                        \
  377                 WITNESS_SAVE(&Giant.lock_object, Giant);                \
  378                 for (_giantcnt = 0; mtx_owned(&Giant); _giantcnt++)     \
  379                         mtx_unlock(&Giant);                             \
  380         }
  381 
  382 #define PICKUP_GIANT()                                                  \
  383         PARTIAL_PICKUP_GIANT();                                         \
  384 } while (0)
  385 
  386 #define PARTIAL_PICKUP_GIANT()                                          \
  387         mtx_assert(&Giant, MA_NOTOWNED);                                \
  388         if (_giantcnt > 0) {                                            \
  389                 while (_giantcnt--)                                     \
  390                         mtx_lock(&Giant);                               \
  391                 WITNESS_RESTORE(&Giant.lock_object, Giant);             \
  392         }
  393 #endif
  394 
  395 #define UGAR(rval) do {                                                 \
  396         int _val = (rval);                                              \
  397         mtx_unlock(&Giant);                                             \
  398         return (_val);                                                  \
  399 } while (0)
  400 
  401 struct mtx_args {
  402         struct mtx      *ma_mtx;
  403         const char      *ma_desc;
  404         int              ma_opts;
  405 };
  406 
  407 #define MTX_SYSINIT(name, mtx, desc, opts)                              \
  408         static struct mtx_args name##_args = {                          \
  409                 (mtx),                                                  \
  410                 (desc),                                                 \
  411                 (opts)                                                  \
  412         };                                                              \
  413         SYSINIT(name##_mtx_sysinit, SI_SUB_LOCK, SI_ORDER_MIDDLE,       \
  414             mtx_sysinit, &name##_args);                                 \
  415         SYSUNINIT(name##_mtx_sysuninit, SI_SUB_LOCK, SI_ORDER_MIDDLE,   \
  416             mtx_destroy, (mtx))
  417 
  418 /*
  419  * The INVARIANTS-enabled mtx_assert() functionality.
  420  *
  421  * The constants need to be defined for INVARIANT_SUPPORT infrastructure
  422  * support as _mtx_assert() itself uses them and the latter implies that
  423  * _mtx_assert() must build.
  424  */
  425 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT)
  426 #define MA_OWNED        LA_XLOCKED
  427 #define MA_NOTOWNED     LA_UNLOCKED
  428 #define MA_RECURSED     LA_RECURSED
  429 #define MA_NOTRECURSED  LA_NOTRECURSED
  430 #endif
  431 
  432 #ifdef INVARIANTS
  433 #define mtx_assert(m, what)                                             \
  434         _mtx_assert((m), (what), __FILE__, __LINE__)
  435 
  436 #define GIANT_REQUIRED  mtx_assert(&Giant, MA_OWNED)
  437 
  438 #else   /* INVARIANTS */
  439 #define mtx_assert(m, what)
  440 #define GIANT_REQUIRED
  441 #endif  /* INVARIANTS */
  442 
  443 /*
  444  * Common lock type names.
  445  */
  446 #define MTX_NETWORK_LOCK        "network driver"
  447 
  448 #endif  /* _KERNEL */
  449 #endif  /* !LOCORE */
  450 #endif  /* _SYS_MUTEX_H_ */

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