xref: /freebsd/sys/sys/mutex.h (revision d6b92ffa)
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_MUTEX_H_
33 #define _SYS_MUTEX_H_
34 
35 #include <sys/queue.h>
36 #include <sys/_lock.h>
37 #include <sys/_mutex.h>
38 
39 #ifdef _KERNEL
40 #include <sys/pcpu.h>
41 #include <sys/lock_profile.h>
42 #include <sys/lockstat.h>
43 #include <machine/atomic.h>
44 #include <machine/cpufunc.h>
45 
46 /*
47  * Mutex types and options passed to mtx_init().  MTX_QUIET and MTX_DUPOK
48  * can also be passed in.
49  */
50 #define	MTX_DEF		0x00000000	/* DEFAULT (sleep) lock */
51 #define MTX_SPIN	0x00000001	/* Spin lock (disables interrupts) */
52 #define MTX_RECURSE	0x00000004	/* Option: lock allowed to recurse */
53 #define	MTX_NOWITNESS	0x00000008	/* Don't do any witness checking. */
54 #define MTX_NOPROFILE   0x00000020	/* Don't profile this lock */
55 #define	MTX_NEW		0x00000040	/* Don't check for double-init */
56 
57 /*
58  * Option flags passed to certain lock/unlock routines, through the use
59  * of corresponding mtx_{lock,unlock}_flags() interface macros.
60  */
61 #define	MTX_QUIET	LOP_QUIET	/* Don't log a mutex event */
62 #define	MTX_DUPOK	LOP_DUPOK	/* Don't log a duplicate acquire */
63 
64 /*
65  * State bits kept in mutex->mtx_lock, for the DEFAULT lock type. None of this,
66  * with the exception of MTX_UNOWNED, applies to spin locks.
67  */
68 #define	MTX_RECURSED	0x00000001	/* lock recursed (for MTX_DEF only) */
69 #define	MTX_CONTESTED	0x00000002	/* lock contested (for MTX_DEF only) */
70 #define MTX_UNOWNED	0x00000004	/* Cookie for free mutex */
71 #define	MTX_FLAGMASK	(MTX_RECURSED | MTX_CONTESTED | MTX_UNOWNED)
72 
73 /*
74  * Value stored in mutex->mtx_lock to denote a destroyed mutex.
75  */
76 #define	MTX_DESTROYED	(MTX_CONTESTED | MTX_UNOWNED)
77 
78 /*
79  * Prototypes
80  *
81  * NOTE: Functions prepended with `_' (underscore) are exported to other parts
82  *	 of the kernel via macros, thus allowing us to use the cpp LOCK_FILE
83  *	 and LOCK_LINE or for hiding the lock cookie crunching to the
84  *	 consumers. These functions should not be called directly by any
85  *	 code using the API. Their macros cover their functionality.
86  *	 Functions with a `_' suffix are the entrypoint for the common
87  *	 KPI covering both compat shims and fast path case.  These can be
88  *	 used by consumers willing to pass options, file and line
89  *	 informations, in an option-independent way.
90  *
91  * [See below for descriptions]
92  *
93  */
94 void	_mtx_init(volatile uintptr_t *c, const char *name, const char *type,
95 	    int opts);
96 void	_mtx_destroy(volatile uintptr_t *c);
97 void	mtx_sysinit(void *arg);
98 int	_mtx_trylock_flags_(volatile uintptr_t *c, int opts, const char *file,
99 	    int line);
100 void	mutex_init(void);
101 #if LOCK_DEBUG > 0
102 void	__mtx_lock_sleep(volatile uintptr_t *c, uintptr_t v, uintptr_t tid,
103 	    int opts, const char *file, int line);
104 void	__mtx_unlock_sleep(volatile uintptr_t *c, int opts, const char *file,
105 	    int line);
106 #else
107 void	__mtx_lock_sleep(volatile uintptr_t *c, uintptr_t v, uintptr_t tid);
108 void	__mtx_unlock_sleep(volatile uintptr_t *c);
109 #endif
110 
111 #ifdef SMP
112 void	_mtx_lock_spin_cookie(volatile uintptr_t *c, uintptr_t v, uintptr_t tid,
113 	    int opts, const char *file, int line);
114 #endif
115 void	__mtx_lock_flags(volatile uintptr_t *c, int opts, const char *file,
116 	    int line);
117 void	__mtx_unlock_flags(volatile uintptr_t *c, int opts, const char *file,
118 	    int line);
119 void	__mtx_lock_spin_flags(volatile uintptr_t *c, int opts, const char *file,
120 	     int line);
121 int	__mtx_trylock_spin_flags(volatile uintptr_t *c, int opts,
122 	     const char *file, int line);
123 void	__mtx_unlock_spin_flags(volatile uintptr_t *c, int opts,
124 	    const char *file, int line);
125 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT)
126 void	__mtx_assert(const volatile uintptr_t *c, int what, const char *file,
127 	    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 /*
139  * Top-level macros to provide lock cookie once the actual mtx is passed.
140  * They will also prevent passing a malformed object to the mtx KPI by
141  * failing compilation as the mtx_lock reserved member will not be found.
142  */
143 #define	mtx_init(m, n, t, o)						\
144 	_mtx_init(&(m)->mtx_lock, n, t, o)
145 #define	mtx_destroy(m)							\
146 	_mtx_destroy(&(m)->mtx_lock)
147 #define	mtx_trylock_flags_(m, o, f, l)					\
148 	_mtx_trylock_flags_(&(m)->mtx_lock, o, f, l)
149 #if LOCK_DEBUG > 0
150 #define	_mtx_lock_sleep(m, v, t, o, f, l)				\
151 	__mtx_lock_sleep(&(m)->mtx_lock, v, t, o, f, l)
152 #define	_mtx_unlock_sleep(m, o, f, l)					\
153 	__mtx_unlock_sleep(&(m)->mtx_lock, o, f, l)
154 #else
155 #define	_mtx_lock_sleep(m, v, t, o, f, l)				\
156 	__mtx_lock_sleep(&(m)->mtx_lock, v, t)
157 #define	_mtx_unlock_sleep(m, o, f, l)					\
158 	__mtx_unlock_sleep(&(m)->mtx_lock)
159 #endif
160 #ifdef SMP
161 #define	_mtx_lock_spin(m, v, t, o, f, l)				\
162 	_mtx_lock_spin_cookie(&(m)->mtx_lock, v, t, o, f, l)
163 #endif
164 #define	_mtx_lock_flags(m, o, f, l)					\
165 	__mtx_lock_flags(&(m)->mtx_lock, o, f, l)
166 #define	_mtx_unlock_flags(m, o, f, l)					\
167 	__mtx_unlock_flags(&(m)->mtx_lock, o, f, l)
168 #define	_mtx_lock_spin_flags(m, o, f, l)				\
169 	__mtx_lock_spin_flags(&(m)->mtx_lock, o, f, l)
170 #define	_mtx_trylock_spin_flags(m, o, f, l)				\
171 	__mtx_trylock_spin_flags(&(m)->mtx_lock, o, f, l)
172 #define	_mtx_unlock_spin_flags(m, o, f, l)				\
173 	__mtx_unlock_spin_flags(&(m)->mtx_lock, o, f, l)
174 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT)
175 #define	_mtx_assert(m, w, f, l)						\
176 	__mtx_assert(&(m)->mtx_lock, w, f, l)
177 #endif
178 
179 #define	mtx_recurse	lock_object.lo_data
180 
181 /* Very simple operations on mtx_lock. */
182 
183 /* Try to obtain mtx_lock once. */
184 #define _mtx_obtain_lock(mp, tid)					\
185 	atomic_cmpset_acq_ptr(&(mp)->mtx_lock, MTX_UNOWNED, (tid))
186 
187 #define _mtx_obtain_lock_fetch(mp, vp, tid)				\
188 	atomic_fcmpset_acq_ptr(&(mp)->mtx_lock, vp, (tid))
189 
190 /* Try to release mtx_lock if it is unrecursed and uncontested. */
191 #define _mtx_release_lock(mp, tid)					\
192 	atomic_cmpset_rel_ptr(&(mp)->mtx_lock, (tid), MTX_UNOWNED)
193 
194 /* Release mtx_lock quickly, assuming we own it. */
195 #define _mtx_release_lock_quick(mp)					\
196 	atomic_store_rel_ptr(&(mp)->mtx_lock, MTX_UNOWNED)
197 
198 /*
199  * Full lock operations that are suitable to be inlined in non-debug
200  * kernels.  If the lock cannot be acquired or released trivially then
201  * the work is deferred to another function.
202  */
203 
204 /* Lock a normal mutex. */
205 #define __mtx_lock(mp, tid, opts, file, line) do {			\
206 	uintptr_t _tid = (uintptr_t)(tid);				\
207 	uintptr_t _v = MTX_UNOWNED;					\
208 									\
209 	if (__predict_false(LOCKSTAT_PROFILE_ENABLED(adaptive__acquire) ||\
210 	    !_mtx_obtain_lock_fetch((mp), &_v, _tid)))			\
211 		_mtx_lock_sleep((mp), _v, _tid, (opts), (file), (line));\
212 } while (0)
213 
214 /*
215  * Lock a spin mutex.  For spinlocks, we handle recursion inline (it
216  * turns out that function calls can be significantly expensive on
217  * some architectures).  Since spin locks are not _too_ common,
218  * inlining this code is not too big a deal.
219  */
220 #ifdef SMP
221 #define __mtx_lock_spin(mp, tid, opts, file, line) do {			\
222 	uintptr_t _tid = (uintptr_t)(tid);				\
223 	uintptr_t _v = MTX_UNOWNED;					\
224 									\
225 	spinlock_enter();						\
226 	if (!_mtx_obtain_lock_fetch((mp), &_v, _tid)) 			\
227 		_mtx_lock_spin((mp), _v, _tid, (opts), (file), (line)); \
228 	else 								\
229 		LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(spin__acquire,	\
230 		    mp, 0, 0, file, line);				\
231 } while (0)
232 #define __mtx_trylock_spin(mp, tid, opts, file, line) __extension__  ({	\
233 	uintptr_t _tid = (uintptr_t)(tid);				\
234 	int _ret;							\
235 									\
236 	spinlock_enter();						\
237 	if (((mp)->mtx_lock != MTX_UNOWNED || !_mtx_obtain_lock((mp), _tid))) {\
238 		spinlock_exit();					\
239 		_ret = 0;						\
240 	} else {							\
241 		LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(spin__acquire,	\
242 		    mp, 0, 0, file, line);				\
243 		_ret = 1;						\
244 	}								\
245 	_ret;								\
246 })
247 #else /* SMP */
248 #define __mtx_lock_spin(mp, tid, opts, file, line) do {			\
249 	uintptr_t _tid = (uintptr_t)(tid);				\
250 									\
251 	spinlock_enter();						\
252 	if ((mp)->mtx_lock == _tid)					\
253 		(mp)->mtx_recurse++;					\
254 	else {								\
255 		KASSERT((mp)->mtx_lock == MTX_UNOWNED, ("corrupt spinlock")); \
256 		(mp)->mtx_lock = _tid;					\
257 	}								\
258 } while (0)
259 #define __mtx_trylock_spin(mp, tid, opts, file, line) __extension__  ({	\
260 	uintptr_t _tid = (uintptr_t)(tid);				\
261 	int _ret;							\
262 									\
263 	spinlock_enter();						\
264 	if ((mp)->mtx_lock != MTX_UNOWNED) {				\
265 		spinlock_exit();					\
266 		_ret = 0;						\
267 	} else {							\
268 		(mp)->mtx_lock = _tid;					\
269 		_ret = 1;						\
270 	}								\
271 	_ret;								\
272 })
273 #endif /* SMP */
274 
275 /* Unlock a normal mutex. */
276 #define __mtx_unlock(mp, tid, opts, file, line) do {			\
277 	uintptr_t _tid = (uintptr_t)(tid);				\
278 									\
279 	if (__predict_false(LOCKSTAT_PROFILE_ENABLED(adaptive__release) ||\
280 	    !_mtx_release_lock((mp), _tid)))				\
281 		_mtx_unlock_sleep((mp), (opts), (file), (line));	\
282 } while (0)
283 
284 /*
285  * Unlock a spin mutex.  For spinlocks, we can handle everything
286  * inline, as it's pretty simple and a function call would be too
287  * expensive (at least on some architectures).  Since spin locks are
288  * not _too_ common, inlining this code is not too big a deal.
289  *
290  * Since we always perform a spinlock_enter() when attempting to acquire a
291  * spin lock, we need to always perform a matching spinlock_exit() when
292  * releasing a spin lock.  This includes the recursion cases.
293  */
294 #ifdef SMP
295 #define __mtx_unlock_spin(mp) do {					\
296 	if (mtx_recursed((mp)))						\
297 		(mp)->mtx_recurse--;					\
298 	else {								\
299 		LOCKSTAT_PROFILE_RELEASE_LOCK(spin__release, mp);	\
300 		_mtx_release_lock_quick((mp));				\
301 	}								\
302 	spinlock_exit();						\
303 } while (0)
304 #else /* SMP */
305 #define __mtx_unlock_spin(mp) do {					\
306 	if (mtx_recursed((mp)))						\
307 		(mp)->mtx_recurse--;					\
308 	else {								\
309 		LOCKSTAT_PROFILE_RELEASE_LOCK(spin__release, mp);	\
310 		(mp)->mtx_lock = MTX_UNOWNED;				\
311 	}								\
312 	spinlock_exit();						\
313 } while (0)
314 #endif /* SMP */
315 
316 /*
317  * Exported lock manipulation interface.
318  *
319  * mtx_lock(m) locks MTX_DEF mutex `m'
320  *
321  * mtx_lock_spin(m) locks MTX_SPIN mutex `m'
322  *
323  * mtx_unlock(m) unlocks MTX_DEF mutex `m'
324  *
325  * mtx_unlock_spin(m) unlocks MTX_SPIN mutex `m'
326  *
327  * mtx_lock_spin_flags(m, opts) and mtx_lock_flags(m, opts) locks mutex `m'
328  *     and passes option flags `opts' to the "hard" function, if required.
329  *     With these routines, it is possible to pass flags such as MTX_QUIET
330  *     to the appropriate lock manipulation routines.
331  *
332  * mtx_trylock(m) attempts to acquire MTX_DEF mutex `m' but doesn't sleep if
333  *     it cannot. Rather, it returns 0 on failure and non-zero on success.
334  *     It does NOT handle recursion as we assume that if a caller is properly
335  *     using this part of the interface, he will know that the lock in question
336  *     is _not_ recursed.
337  *
338  * mtx_trylock_flags(m, opts) is used the same way as mtx_trylock() but accepts
339  *     relevant option flags `opts.'
340  *
341  * mtx_trylock_spin(m) attempts to acquire MTX_SPIN mutex `m' but doesn't
342  *     spin if it cannot.  Rather, it returns 0 on failure and non-zero on
343  *     success.  It always returns failure for recursed lock attempts.
344  *
345  * mtx_initialized(m) returns non-zero if the lock `m' has been initialized.
346  *
347  * mtx_owned(m) returns non-zero if the current thread owns the lock `m'
348  *
349  * mtx_recursed(m) returns non-zero if the lock `m' is presently recursed.
350  */
351 #define mtx_lock(m)		mtx_lock_flags((m), 0)
352 #define mtx_lock_spin(m)	mtx_lock_spin_flags((m), 0)
353 #define mtx_trylock(m)		mtx_trylock_flags((m), 0)
354 #define mtx_trylock_spin(m)	mtx_trylock_spin_flags((m), 0)
355 #define mtx_unlock(m)		mtx_unlock_flags((m), 0)
356 #define mtx_unlock_spin(m)	mtx_unlock_spin_flags((m), 0)
357 
358 struct mtx_pool;
359 
360 struct mtx_pool *mtx_pool_create(const char *mtx_name, int pool_size, int opts);
361 void mtx_pool_destroy(struct mtx_pool **poolp);
362 struct mtx *mtx_pool_find(struct mtx_pool *pool, void *ptr);
363 struct mtx *mtx_pool_alloc(struct mtx_pool *pool);
364 #define mtx_pool_lock(pool, ptr)					\
365 	mtx_lock(mtx_pool_find((pool), (ptr)))
366 #define mtx_pool_lock_spin(pool, ptr)					\
367 	mtx_lock_spin(mtx_pool_find((pool), (ptr)))
368 #define mtx_pool_unlock(pool, ptr)					\
369 	mtx_unlock(mtx_pool_find((pool), (ptr)))
370 #define mtx_pool_unlock_spin(pool, ptr)					\
371 	mtx_unlock_spin(mtx_pool_find((pool), (ptr)))
372 
373 /*
374  * mtxpool_sleep is a general purpose pool of sleep mutexes.
375  */
376 extern struct mtx_pool *mtxpool_sleep;
377 
378 #ifndef LOCK_DEBUG
379 #error LOCK_DEBUG not defined, include <sys/lock.h> before <sys/mutex.h>
380 #endif
381 #if LOCK_DEBUG > 0 || defined(MUTEX_NOINLINE)
382 #define	mtx_lock_flags_(m, opts, file, line)				\
383 	_mtx_lock_flags((m), (opts), (file), (line))
384 #define	mtx_unlock_flags_(m, opts, file, line)				\
385 	_mtx_unlock_flags((m), (opts), (file), (line))
386 #define	mtx_lock_spin_flags_(m, opts, file, line)			\
387 	_mtx_lock_spin_flags((m), (opts), (file), (line))
388 #define	mtx_trylock_spin_flags_(m, opts, file, line)			\
389 	_mtx_trylock_spin_flags((m), (opts), (file), (line))
390 #define	mtx_unlock_spin_flags_(m, opts, file, line)			\
391 	_mtx_unlock_spin_flags((m), (opts), (file), (line))
392 #else	/* LOCK_DEBUG == 0 && !MUTEX_NOINLINE */
393 #define	mtx_lock_flags_(m, opts, file, line)				\
394 	__mtx_lock((m), curthread, (opts), (file), (line))
395 #define	mtx_unlock_flags_(m, opts, file, line)				\
396 	__mtx_unlock((m), curthread, (opts), (file), (line))
397 #define	mtx_lock_spin_flags_(m, opts, file, line)			\
398 	__mtx_lock_spin((m), curthread, (opts), (file), (line))
399 #define	mtx_trylock_spin_flags_(m, opts, file, line)			\
400 	__mtx_trylock_spin((m), curthread, (opts), (file), (line))
401 #define	mtx_unlock_spin_flags_(m, opts, file, line)			\
402 	__mtx_unlock_spin((m))
403 #endif	/* LOCK_DEBUG > 0 || MUTEX_NOINLINE */
404 
405 #ifdef INVARIANTS
406 #define	mtx_assert_(m, what, file, line)				\
407 	_mtx_assert((m), (what), (file), (line))
408 
409 #define GIANT_REQUIRED	mtx_assert_(&Giant, MA_OWNED, __FILE__, __LINE__)
410 
411 #else	/* INVARIANTS */
412 #define mtx_assert_(m, what, file, line)	(void)0
413 #define GIANT_REQUIRED
414 #endif	/* INVARIANTS */
415 
416 #define	mtx_lock_flags(m, opts)						\
417 	mtx_lock_flags_((m), (opts), LOCK_FILE, LOCK_LINE)
418 #define	mtx_unlock_flags(m, opts)					\
419 	mtx_unlock_flags_((m), (opts), LOCK_FILE, LOCK_LINE)
420 #define	mtx_lock_spin_flags(m, opts)					\
421 	mtx_lock_spin_flags_((m), (opts), LOCK_FILE, LOCK_LINE)
422 #define	mtx_unlock_spin_flags(m, opts)					\
423 	mtx_unlock_spin_flags_((m), (opts), LOCK_FILE, LOCK_LINE)
424 #define mtx_trylock_flags(m, opts)					\
425 	mtx_trylock_flags_((m), (opts), LOCK_FILE, LOCK_LINE)
426 #define mtx_trylock_spin_flags(m, opts)					\
427 	mtx_trylock_spin_flags_((m), (opts), LOCK_FILE, LOCK_LINE)
428 #define	mtx_assert(m, what)						\
429 	mtx_assert_((m), (what), __FILE__, __LINE__)
430 
431 #define	mtx_sleep(chan, mtx, pri, wmesg, timo)				\
432 	_sleep((chan), &(mtx)->lock_object, (pri), (wmesg),		\
433 	    tick_sbt * (timo), 0, C_HARDCLOCK)
434 
435 #define	MTX_READ_VALUE(m)	((m)->mtx_lock)
436 
437 #define	mtx_initialized(m)	lock_initialized(&(m)->lock_object)
438 
439 #define lv_mtx_owner(v)	((struct thread *)((v) & ~MTX_FLAGMASK))
440 
441 #define mtx_owner(m)	lv_mtx_owner(MTX_READ_VALUE(m))
442 
443 #define mtx_owned(m)	(mtx_owner(m) == curthread)
444 
445 #define mtx_recursed(m)	((m)->mtx_recurse != 0)
446 
447 #define mtx_name(m)	((m)->lock_object.lo_name)
448 
449 /*
450  * Global locks.
451  */
452 extern struct mtx Giant;
453 extern struct mtx blocked_lock;
454 
455 /*
456  * Giant lock manipulation and clean exit macros.
457  * Used to replace return with an exit Giant and return.
458  *
459  * Note that DROP_GIANT*() needs to be paired with PICKUP_GIANT()
460  * The #ifndef is to allow lint-like tools to redefine DROP_GIANT.
461  */
462 #ifndef DROP_GIANT
463 #define DROP_GIANT()							\
464 do {									\
465 	int _giantcnt = 0;						\
466 	WITNESS_SAVE_DECL(Giant);					\
467 									\
468 	if (mtx_owned(&Giant)) {					\
469 		WITNESS_SAVE(&Giant.lock_object, Giant);		\
470 		for (_giantcnt = 0; mtx_owned(&Giant) &&		\
471 		    !SCHEDULER_STOPPED(); _giantcnt++)			\
472 			mtx_unlock(&Giant);				\
473 	}
474 
475 #define PICKUP_GIANT()							\
476 	PARTIAL_PICKUP_GIANT();						\
477 } while (0)
478 
479 #define PARTIAL_PICKUP_GIANT()						\
480 	mtx_assert(&Giant, MA_NOTOWNED);				\
481 	if (_giantcnt > 0) {						\
482 		while (_giantcnt--)					\
483 			mtx_lock(&Giant);				\
484 		WITNESS_RESTORE(&Giant.lock_object, Giant);		\
485 	}
486 #endif
487 
488 struct mtx_args {
489 	void		*ma_mtx;
490 	const char 	*ma_desc;
491 	int		 ma_opts;
492 };
493 
494 #define	MTX_SYSINIT(name, mtx, desc, opts)				\
495 	static struct mtx_args name##_args = {				\
496 		(mtx),							\
497 		(desc),							\
498 		(opts)							\
499 	};								\
500 	SYSINIT(name##_mtx_sysinit, SI_SUB_LOCK, SI_ORDER_MIDDLE,	\
501 	    mtx_sysinit, &name##_args);					\
502 	SYSUNINIT(name##_mtx_sysuninit, SI_SUB_LOCK, SI_ORDER_MIDDLE,	\
503 	    _mtx_destroy, __DEVOLATILE(void *, &(mtx)->mtx_lock))
504 
505 /*
506  * The INVARIANTS-enabled mtx_assert() functionality.
507  *
508  * The constants need to be defined for INVARIANT_SUPPORT infrastructure
509  * support as _mtx_assert() itself uses them and the latter implies that
510  * _mtx_assert() must build.
511  */
512 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT)
513 #define MA_OWNED	LA_XLOCKED
514 #define MA_NOTOWNED	LA_UNLOCKED
515 #define MA_RECURSED	LA_RECURSED
516 #define MA_NOTRECURSED	LA_NOTRECURSED
517 #endif
518 
519 /*
520  * Common lock type names.
521  */
522 #define	MTX_NETWORK_LOCK	"network driver"
523 
524 #endif	/* _KERNEL */
525 #endif	/* _SYS_MUTEX_H_ */
526