2 * Copyright (c) 1997 Berkeley Software Design, Inc. All rights reserved.
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
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
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
28 * from BSDI $Id: mutex.h,v 2.7.2.35 2000/04/27 03:10:26 cp Exp $
36 #include <sys/queue.h>
37 #include <sys/_lock.h>
38 #include <sys/_mutex.h>
42 #include <machine/atomic.h>
43 #include <machine/cpufunc.h>
47 #include <machine/mutex.h>
52 * Mutex types and options passed to mtx_init(). MTX_QUIET can also be
55 #define MTX_DEF 0x00000000 /* DEFAULT (sleep) lock */
56 #define MTX_SPIN 0x00000001 /* Spin lock (disables interrupts) */
57 #define MTX_RECURSE 0x00000004 /* Option: lock allowed to recurse */
58 #define MTX_NOWITNESS 0x00000008 /* Don't do any witness checking. */
59 #define MTX_SLEEPABLE 0x00000010 /* We can sleep with this lock. */
60 #define MTX_DUPOK 0x00000020 /* Don't log a duplicate acquire */
63 * Option flags passed to certain lock/unlock routines, through the use
64 * of corresponding mtx_{lock,unlock}_flags() interface macros.
66 #define MTX_QUIET LOP_QUIET /* Don't log a mutex event */
69 * State bits kept in mutex->mtx_lock, for the DEFAULT lock type. None of this,
70 * with the exception of MTX_UNOWNED, applies to spin locks.
72 #define MTX_RECURSED 0x00000001 /* lock recursed (for MTX_DEF only) */
73 #define MTX_CONTESTED 0x00000002 /* lock contested (for MTX_DEF only) */
74 #define MTX_UNOWNED 0x00000004 /* Cookie for free mutex */
75 #define MTX_FLAGMASK ~(MTX_RECURSED | MTX_CONTESTED)
82 * XXX: Friendly reminder to fix things in MP code that is presently being
85 #define mp_fixme(string)
92 * NOTE: Functions prepended with `_' (underscore) are exported to other parts
93 * of the kernel via macros, thus allowing us to use the cpp LOCK_FILE
94 * and LOCK_LINE. These functions should not be called directly by any
95 * code using the API. Their macros cover their functionality.
97 * [See below for descriptions]
100 void mtx_init(struct mtx *m, const char *name, const char *type, int opts);
101 void mtx_destroy(struct mtx *m);
102 void mtx_sysinit(void *arg);
103 void mutex_init(void);
104 void _mtx_lock_sleep(struct mtx *m, int opts, const char *file, int line);
105 void _mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line);
106 void _mtx_lock_spin(struct mtx *m, int opts, const char *file, int line);
107 void _mtx_unlock_spin(struct mtx *m, int opts, const char *file, int line);
108 int _mtx_trylock(struct mtx *m, int opts, const char *file, int line);
109 void _mtx_lock_flags(struct mtx *m, int opts, const char *file, int line);
110 void _mtx_unlock_flags(struct mtx *m, int opts, const char *file, int line);
111 void _mtx_lock_spin_flags(struct mtx *m, int opts, const char *file,
113 void _mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file,
115 #ifdef INVARIANT_SUPPORT
116 void _mtx_assert(struct mtx *m, int what, const char *file, int line);
118 int mtx_lock_giant(int sysctlvar);
119 void mtx_unlock_giant(int s);
122 * We define our machine-independent (unoptimized) mutex micro-operations
123 * here, if they are not already defined in the machine-dependent mutex.h
126 /* Actually obtain mtx_lock */
128 #define _obtain_lock(mp, tid) \
129 atomic_cmpset_acq_ptr(&(mp)->mtx_lock, (void *)MTX_UNOWNED, (tid))
132 /* Actually release mtx_lock */
133 #ifndef _release_lock
134 #define _release_lock(mp, tid) \
135 atomic_cmpset_rel_ptr(&(mp)->mtx_lock, (tid), (void *)MTX_UNOWNED)
138 /* Actually release mtx_lock quickly, assuming we own it. */
139 #ifndef _release_lock_quick
140 #define _release_lock_quick(mp) \
141 atomic_store_rel_ptr(&(mp)->mtx_lock, (void *)MTX_UNOWNED)
145 * Obtain a sleep lock inline, or call the "hard" function if we can't get it
148 #ifndef _get_sleep_lock
149 #define _get_sleep_lock(mp, tid, opts, file, line) do { \
150 if (!_obtain_lock((mp), (tid))) \
151 _mtx_lock_sleep((mp), (opts), (file), (line)); \
156 * Obtain a spin lock inline, or call the "hard" function if we can't get it
157 * easy. For spinlocks, we handle recursion inline (it turns out that function
158 * calls can be significantly expensive on some architectures).
159 * Since spin locks are not _too_ common, inlining this code is not too big
162 #ifndef _get_spin_lock
163 #define _get_spin_lock(mp, tid, opts, file, line) do { \
165 if (!_obtain_lock((mp), (tid))) { \
166 if ((mp)->mtx_lock == (uintptr_t)(tid)) \
167 (mp)->mtx_recurse++; \
169 _mtx_lock_spin((mp), (opts), (file), (line)); \
175 * Release a sleep lock inline, or call the "hard" function if we can't do it
178 #ifndef _rel_sleep_lock
179 #define _rel_sleep_lock(mp, tid, opts, file, line) do { \
180 if (!_release_lock((mp), (tid))) \
181 _mtx_unlock_sleep((mp), (opts), (file), (line)); \
186 * For spinlocks, we can handle everything inline, as it's pretty simple and
187 * a function call would be too expensive (at least on some architectures).
188 * Since spin locks are not _too_ common, inlining this code is not too big
191 * Since we always perform a critical_enter() when attempting to acquire a
192 * spin lock, we need to always perform a matching critical_exit() when
193 * releasing a spin lock. This includes the recursion cases.
195 #ifndef _rel_spin_lock
196 #define _rel_spin_lock(mp) do { \
197 if (mtx_recursed((mp))) \
198 (mp)->mtx_recurse--; \
200 _release_lock_quick((mp)); \
206 * Exported lock manipulation interface.
208 * mtx_lock(m) locks MTX_DEF mutex `m'
210 * mtx_lock_spin(m) locks MTX_SPIN mutex `m'
212 * mtx_unlock(m) unlocks MTX_DEF mutex `m'
214 * mtx_unlock_spin(m) unlocks MTX_SPIN mutex `m'
216 * mtx_lock_spin_flags(m, opts) and mtx_lock_flags(m, opts) locks mutex `m'
217 * and passes option flags `opts' to the "hard" function, if required.
218 * With these routines, it is possible to pass flags such as MTX_QUIET
219 * to the appropriate lock manipulation routines.
221 * mtx_trylock(m) attempts to acquire MTX_DEF mutex `m' but doesn't sleep if
222 * it cannot. Rather, it returns 0 on failure and non-zero on success.
223 * It does NOT handle recursion as we assume that if a caller is properly
224 * using this part of the interface, he will know that the lock in question
227 * mtx_trylock_flags(m, opts) is used the same way as mtx_trylock() but accepts
228 * relevant option flags `opts.'
230 * mtx_initialized(m) returns non-zero if the lock `m' has been initialized.
232 * mtx_owned(m) returns non-zero if the current thread owns the lock `m'
234 * mtx_recursed(m) returns non-zero if the lock `m' is presently recursed.
236 #define mtx_lock(m) mtx_lock_flags((m), 0)
237 #define mtx_lock_spin(m) mtx_lock_spin_flags((m), 0)
238 #define mtx_trylock(m) mtx_trylock_flags((m), 0)
239 #define mtx_unlock(m) mtx_unlock_flags((m), 0)
240 #define mtx_unlock_spin(m) mtx_unlock_spin_flags((m), 0)
242 struct mtx *mtx_pool_find(void *ptr);
243 struct mtx *mtx_pool_alloc(void);
244 void mtx_pool_lock(void *ptr);
245 void mtx_pool_unlock(void *ptr);
247 extern int mtx_pool_valid;
250 #error LOCK_DEBUG not defined, include <sys/lock.h> before <sys/mutex.h>
253 #define mtx_lock_flags(m, opts) \
254 _mtx_lock_flags((m), (opts), LOCK_FILE, LOCK_LINE)
255 #define mtx_unlock_flags(m, opts) \
256 _mtx_unlock_flags((m), (opts), LOCK_FILE, LOCK_LINE)
257 #define mtx_lock_spin_flags(m, opts) \
258 _mtx_lock_spin_flags((m), (opts), LOCK_FILE, LOCK_LINE)
259 #define mtx_unlock_spin_flags(m, opts) \
260 _mtx_unlock_spin_flags((m), (opts), LOCK_FILE, LOCK_LINE)
261 #else /* LOCK_DEBUG == 0 */
262 #define mtx_lock_flags(m, opts) \
263 _get_sleep_lock((m), curthread, (opts), LOCK_FILE, LOCK_LINE)
264 #define mtx_unlock_flags(m, opts) \
265 _rel_sleep_lock((m), curthread, (opts), LOCK_FILE, LOCK_LINE)
267 #define mtx_lock_spin_flags(m, opts) \
268 _get_spin_lock((m), curthread, (opts), LOCK_FILE, LOCK_LINE)
269 #define mtx_unlock_spin_flags(m, opts) \
272 #define mtx_lock_spin_flags(m, opts) critical_enter()
273 #define mtx_unlock_spin_flags(m, opts) critical_exit()
275 #endif /* LOCK_DEBUG */
277 #define mtx_trylock_flags(m, opts) \
278 _mtx_trylock((m), (opts), LOCK_FILE, LOCK_LINE)
280 #define mtx_initialized(m) ((m)->mtx_object.lo_flags & LO_INITIALIZED)
282 #define mtx_owned(m) (((m)->mtx_lock & MTX_FLAGMASK) == (uintptr_t)curthread)
284 #define mtx_recursed(m) ((m)->mtx_recurse != 0)
286 #define mtx_name(m) ((m)->mtx_object.lo_name)
291 extern struct mtx sched_lock;
292 extern struct mtx Giant;
295 * Giant lock sysctl variables used by other modules
297 extern int kern_giant_proc;
298 extern int kern_giant_file;
299 extern int kern_giant_ucred;
302 * Giant lock manipulation and clean exit macros.
303 * Used to replace return with an exit Giant and return.
305 * Note that DROP_GIANT*() needs to be paired with PICKUP_GIANT()
307 #define DROP_GIANT() \
310 WITNESS_SAVE_DECL(Giant); \
312 if (mtx_owned(&Giant)) \
313 WITNESS_SAVE(&Giant.mtx_object, Giant); \
314 for (_giantcnt = 0; mtx_owned(&Giant); _giantcnt++) \
317 #define PICKUP_GIANT() \
318 mtx_assert(&Giant, MA_NOTOWNED); \
319 while (_giantcnt--) \
321 if (mtx_owned(&Giant)) \
322 WITNESS_RESTORE(&Giant.mtx_object, Giant); \
325 #define PARTIAL_PICKUP_GIANT() \
326 mtx_assert(&Giant, MA_NOTOWNED); \
327 while (_giantcnt--) \
329 if (mtx_owned(&Giant)) \
330 WITNESS_RESTORE(&Giant.mtx_object, Giant)
332 #define UGAR(rval) do { \
334 mtx_unlock(&Giant); \
344 #define MTX_SYSINIT(name, mtx, desc, opts) \
345 static struct mtx_args name##_args = { \
350 SYSINIT(name##_mtx_sysinit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \
351 mtx_sysinit, &name##_args)
354 * The INVARIANTS-enabled mtx_assert() functionality.
356 * The constants need to be defined for INVARIANT_SUPPORT infrastructure
357 * support as _mtx_assert() itself uses them and the latter implies that
358 * _mtx_assert() must build.
360 #ifdef INVARIANT_SUPPORT
361 #define MA_OWNED 0x01
362 #define MA_NOTOWNED 0x02
363 #define MA_RECURSED 0x04
364 #define MA_NOTRECURSED 0x08
365 #endif /* INVARIANT_SUPPORT */
368 #define mtx_assert(m, what) \
369 _mtx_assert((m), (what), __FILE__, __LINE__)
371 #define GIANT_REQUIRED mtx_assert(&Giant, MA_OWNED)
373 #else /* INVARIANTS */
374 #define mtx_assert(m, what)
375 #define GIANT_REQUIRED
376 #endif /* INVARIANTS */
379 * Common lock type names.
381 #define MTX_NETWORK_LOCK "network driver"
385 #endif /* _SYS_MUTEX_H_ */