FreeBSD/Linux Kernel Cross Reference
sys/sys/mutex.h
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/6.0/sys/sys/mutex.h 148757 2005-08-05 20:21:46Z 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 <machine/atomic.h>
43 #include <machine/cpufunc.h>
44 #endif /* _KERNEL_ */
45 #endif /* !LOCORE */
46
47 #include <machine/mutex.h>
48
49 #ifdef _KERNEL
50
51 /*
52 * Mutex types and options passed to mtx_init(). MTX_QUIET and MTX_DUPOK
53 * can also be passed in.
54 */
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
60 /*
61 * Option flags passed to certain lock/unlock routines, through the use
62 * of corresponding mtx_{lock,unlock}_flags() interface macros.
63 */
64 #define MTX_QUIET LOP_QUIET /* Don't log a mutex event */
65 #define MTX_DUPOK LOP_DUPOK /* Don't log a duplicate acquire */
66
67 /*
68 * State bits kept in mutex->mtx_lock, for the DEFAULT lock type. None of this,
69 * with the exception of MTX_UNOWNED, applies to spin locks.
70 */
71 #define MTX_RECURSED 0x00000001 /* lock recursed (for MTX_DEF only) */
72 #define MTX_CONTESTED 0x00000002 /* lock contested (for MTX_DEF only) */
73 #define MTX_UNOWNED 0x00000004 /* Cookie for free mutex */
74 #define MTX_FLAGMASK ~(MTX_RECURSED | MTX_CONTESTED)
75
76 #endif /* _KERNEL */
77
78 #ifndef LOCORE
79
80 /*
81 * XXX: Friendly reminder to fix things in MP code that is presently being
82 * XXX: worked on.
83 */
84 #define mp_fixme(string)
85
86 #ifdef _KERNEL
87
88 /*
89 * Prototypes
90 *
91 * NOTE: Functions prepended with `_' (underscore) are exported to other parts
92 * of the kernel via macros, thus allowing us to use the cpp LOCK_FILE
93 * and LOCK_LINE. These functions should not be called directly by any
94 * code using the API. Their macros cover their functionality.
95 *
96 * [See below for descriptions]
97 *
98 */
99 void mtx_init(struct mtx *m, const char *name, const char *type, int opts);
100 void mtx_destroy(struct mtx *m);
101 void mtx_sysinit(void *arg);
102 void mutex_init(void);
103 void _mtx_lock_sleep(struct mtx *m, uintptr_t tid, int opts,
104 const char *file, int line);
105 void _mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line);
106 #ifdef SMP
107 void _mtx_lock_spin(struct mtx *m, uintptr_t tid, int opts,
108 const char *file, int line);
109 #endif
110 void _mtx_unlock_spin(struct mtx *m, int opts, const char *file, int line);
111 int _mtx_trylock(struct mtx *m, int opts, const char *file, int line);
112 void _mtx_lock_flags(struct mtx *m, int opts, const char *file, int line);
113 void _mtx_unlock_flags(struct mtx *m, int opts, const char *file, int line);
114 void _mtx_lock_spin_flags(struct mtx *m, int opts, const char *file,
115 int line);
116 void _mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file,
117 int line);
118 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT)
119 void _mtx_assert(struct mtx *m, int what, const char *file, int line);
120 #endif
121
122 /*
123 * We define our machine-independent (unoptimized) mutex micro-operations
124 * here, if they are not already defined in the machine-dependent mutex.h
125 */
126
127 /* Try to obtain mtx_lock once. */
128 #ifndef _obtain_lock
129 #define _obtain_lock(mp, tid) \
130 atomic_cmpset_acq_ptr(&(mp)->mtx_lock, MTX_UNOWNED, (tid))
131 #endif
132
133 /* Try to release mtx_lock if it is unrecursed and uncontested. */
134 #ifndef _release_lock
135 #define _release_lock(mp, tid) \
136 atomic_cmpset_rel_ptr(&(mp)->mtx_lock, (tid), MTX_UNOWNED)
137 #endif
138
139 /* Release mtx_lock quickly, assuming we own it. */
140 #ifndef _release_lock_quick
141 #define _release_lock_quick(mp) \
142 atomic_store_rel_ptr(&(mp)->mtx_lock, MTX_UNOWNED)
143 #endif
144
145 /*
146 * Obtain a sleep lock inline, or call the "hard" function if we can't get it
147 * easy.
148 */
149 #ifndef _get_sleep_lock
150 #define _get_sleep_lock(mp, tid, opts, file, line) do { \
151 uintptr_t _tid = (uintptr_t)(tid); \
152 \
153 if (!_obtain_lock((mp), _tid)) \
154 _mtx_lock_sleep((mp), _tid, (opts), (file), (line)); \
155 } while (0)
156 #endif
157
158 /*
159 * Obtain a spin lock inline, or call the "hard" function if we can't get it
160 * easy. For spinlocks, we handle recursion inline (it turns out that function
161 * calls can be significantly expensive on some architectures).
162 * Since spin locks are not _too_ common, inlining this code is not too big
163 * a deal.
164 */
165 #ifndef _get_spin_lock
166 #ifdef SMP
167 #define _get_spin_lock(mp, tid, opts, file, line) do { \
168 uintptr_t _tid = (uintptr_t)(tid); \
169 \
170 spinlock_enter(); \
171 if (!_obtain_lock((mp), _tid)) { \
172 if ((mp)->mtx_lock == _tid) \
173 (mp)->mtx_recurse++; \
174 else \
175 _mtx_lock_spin((mp), _tid, (opts), (file), (line)); \
176 } \
177 } while (0)
178 #else /* SMP */
179 #define _get_spin_lock(mp, tid, opts, file, line) do { \
180 uintptr_t _tid = (uintptr_t)(tid); \
181 \
182 spinlock_enter(); \
183 if ((mp)->mtx_lock == _tid) \
184 (mp)->mtx_recurse++; \
185 else { \
186 KASSERT((mp)->mtx_lock == MTX_UNOWNED, ("corrupt spinlock")); \
187 (mp)->mtx_lock = _tid; \
188 } \
189 } while (0)
190 #endif /* SMP */
191 #endif
192
193 /*
194 * Release a sleep lock inline, or call the "hard" function if we can't do it
195 * easy.
196 */
197 #ifndef _rel_sleep_lock
198 #define _rel_sleep_lock(mp, tid, opts, file, line) do { \
199 uintptr_t _tid = (uintptr_t)(tid); \
200 \
201 if (!_release_lock((mp), _tid)) \
202 _mtx_unlock_sleep((mp), (opts), (file), (line)); \
203 } while (0)
204 #endif
205
206 /*
207 * For spinlocks, we can handle everything inline, as it's pretty simple and
208 * a function call would be too expensive (at least on some architectures).
209 * Since spin locks are not _too_ common, inlining this code is not too big
210 * a deal.
211 *
212 * Since we always perform a spinlock_enter() when attempting to acquire a
213 * spin lock, we need to always perform a matching spinlock_exit() when
214 * releasing a spin lock. This includes the recursion cases.
215 */
216 #ifndef _rel_spin_lock
217 #ifdef SMP
218 #define _rel_spin_lock(mp) do { \
219 if (mtx_recursed((mp))) \
220 (mp)->mtx_recurse--; \
221 else \
222 _release_lock_quick((mp)); \
223 spinlock_exit(); \
224 } while (0)
225 #else /* SMP */
226 #define _rel_spin_lock(mp) do { \
227 if (mtx_recursed((mp))) \
228 (mp)->mtx_recurse--; \
229 else \
230 (mp)->mtx_lock = MTX_UNOWNED; \
231 spinlock_exit(); \
232 } while (0)
233 #endif /* SMP */
234 #endif
235
236 /*
237 * Exported lock manipulation interface.
238 *
239 * mtx_lock(m) locks MTX_DEF mutex `m'
240 *
241 * mtx_lock_spin(m) locks MTX_SPIN mutex `m'
242 *
243 * mtx_unlock(m) unlocks MTX_DEF mutex `m'
244 *
245 * mtx_unlock_spin(m) unlocks MTX_SPIN mutex `m'
246 *
247 * mtx_lock_spin_flags(m, opts) and mtx_lock_flags(m, opts) locks mutex `m'
248 * and passes option flags `opts' to the "hard" function, if required.
249 * With these routines, it is possible to pass flags such as MTX_QUIET
250 * to the appropriate lock manipulation routines.
251 *
252 * mtx_trylock(m) attempts to acquire MTX_DEF mutex `m' but doesn't sleep if
253 * it cannot. Rather, it returns 0 on failure and non-zero on success.
254 * It does NOT handle recursion as we assume that if a caller is properly
255 * using this part of the interface, he will know that the lock in question
256 * is _not_ recursed.
257 *
258 * mtx_trylock_flags(m, opts) is used the same way as mtx_trylock() but accepts
259 * relevant option flags `opts.'
260 *
261 * mtx_initialized(m) returns non-zero if the lock `m' has been initialized.
262 *
263 * mtx_owned(m) returns non-zero if the current thread owns the lock `m'
264 *
265 * mtx_recursed(m) returns non-zero if the lock `m' is presently recursed.
266 */
267 #define mtx_lock(m) mtx_lock_flags((m), 0)
268 #define mtx_lock_spin(m) mtx_lock_spin_flags((m), 0)
269 #define mtx_trylock(m) mtx_trylock_flags((m), 0)
270 #define mtx_unlock(m) mtx_unlock_flags((m), 0)
271 #define mtx_unlock_spin(m) mtx_unlock_spin_flags((m), 0)
272
273 struct mtx_pool;
274
275 struct mtx_pool *mtx_pool_create(const char *mtx_name, int pool_size, int opts);
276 void mtx_pool_destroy(struct mtx_pool **poolp);
277 struct mtx *mtx_pool_find(struct mtx_pool *pool, void *ptr);
278 struct mtx *mtx_pool_alloc(struct mtx_pool *pool);
279 #define mtx_pool_lock(pool, ptr) \
280 mtx_lock(mtx_pool_find((pool), (ptr)))
281 #define mtx_pool_lock_spin(pool, ptr) \
282 mtx_lock_spin(mtx_pool_find((pool), (ptr)))
283 #define mtx_pool_unlock(pool, ptr) \
284 mtx_unlock(mtx_pool_find((pool), (ptr)))
285 #define mtx_pool_unlock_spin(pool, ptr) \
286 mtx_unlock_spin(mtx_pool_find((pool), (ptr)))
287
288 /*
289 * mtxpool_lockbuilder is a pool of sleep locks that is not witness
290 * checked and should only be used for building higher level locks.
291 *
292 * mtxpool_sleep is a general purpose pool of sleep mutexes.
293 */
294 extern struct mtx_pool *mtxpool_lockbuilder;
295 extern struct mtx_pool *mtxpool_sleep;
296
297 #ifndef LOCK_DEBUG
298 #error LOCK_DEBUG not defined, include <sys/lock.h> before <sys/mutex.h>
299 #endif
300 #if LOCK_DEBUG > 0 || defined(MUTEX_NOINLINE)
301 #define mtx_lock_flags(m, opts) \
302 _mtx_lock_flags((m), (opts), LOCK_FILE, LOCK_LINE)
303 #define mtx_unlock_flags(m, opts) \
304 _mtx_unlock_flags((m), (opts), LOCK_FILE, LOCK_LINE)
305 #define mtx_lock_spin_flags(m, opts) \
306 _mtx_lock_spin_flags((m), (opts), LOCK_FILE, LOCK_LINE)
307 #define mtx_unlock_spin_flags(m, opts) \
308 _mtx_unlock_spin_flags((m), (opts), LOCK_FILE, LOCK_LINE)
309 #else /* LOCK_DEBUG == 0 && !MUTEX_NOINLINE */
310 #define mtx_lock_flags(m, opts) \
311 _get_sleep_lock((m), curthread, (opts), LOCK_FILE, LOCK_LINE)
312 #define mtx_unlock_flags(m, opts) \
313 _rel_sleep_lock((m), curthread, (opts), LOCK_FILE, LOCK_LINE)
314 #define mtx_lock_spin_flags(m, opts) \
315 _get_spin_lock((m), curthread, (opts), LOCK_FILE, LOCK_LINE)
316 #define mtx_unlock_spin_flags(m, opts) \
317 _rel_spin_lock((m))
318 #endif /* LOCK_DEBUG > 0 || MUTEX_NOINLINE */
319
320 #define mtx_trylock_flags(m, opts) \
321 _mtx_trylock((m), (opts), LOCK_FILE, LOCK_LINE)
322
323 #define mtx_initialized(m) ((m)->mtx_object.lo_flags & LO_INITIALIZED)
324
325 #define mtx_owned(m) (((m)->mtx_lock & MTX_FLAGMASK) == (uintptr_t)curthread)
326
327 #define mtx_recursed(m) ((m)->mtx_recurse != 0)
328
329 #define mtx_name(m) ((m)->mtx_object.lo_name)
330
331 /*
332 * Global locks.
333 */
334 extern struct mtx sched_lock;
335 extern struct mtx Giant;
336
337 /*
338 * Giant lock manipulation and clean exit macros.
339 * Used to replace return with an exit Giant and return.
340 *
341 * Note that DROP_GIANT*() needs to be paired with PICKUP_GIANT()
342 * The #ifndef is to allow lint-like tools to redefine DROP_GIANT.
343 */
344 #ifndef DROP_GIANT
345 #define DROP_GIANT() \
346 do { \
347 int _giantcnt; \
348 WITNESS_SAVE_DECL(Giant); \
349 \
350 if (mtx_owned(&Giant)) \
351 WITNESS_SAVE(&Giant.mtx_object, Giant); \
352 for (_giantcnt = 0; mtx_owned(&Giant); _giantcnt++) \
353 mtx_unlock(&Giant)
354
355 #define PICKUP_GIANT() \
356 mtx_assert(&Giant, MA_NOTOWNED); \
357 while (_giantcnt--) \
358 mtx_lock(&Giant); \
359 if (mtx_owned(&Giant)) \
360 WITNESS_RESTORE(&Giant.mtx_object, Giant); \
361 } while (0)
362
363 #define PARTIAL_PICKUP_GIANT() \
364 mtx_assert(&Giant, MA_NOTOWNED); \
365 while (_giantcnt--) \
366 mtx_lock(&Giant); \
367 if (mtx_owned(&Giant)) \
368 WITNESS_RESTORE(&Giant.mtx_object, Giant)
369 #endif
370
371 /*
372 * Network MPSAFE temporary workarounds. When debug_mpsafenet
373 * is 1 the network is assumed to operate without Giant on the
374 * input path and protocols that require Giant must collect it
375 * on entry. When 0 Giant is grabbed in the network interface
376 * ISR's and in the netisr path and there is no need to grab
377 * the Giant lock. Note that, unlike GIANT_PICKUP() and
378 * GIANT_DROP(), these macros directly wrap mutex operations
379 * without special recursion handling.
380 *
381 * This mechanism is intended as temporary until everything of
382 * importance is properly locked. Note: the semantics for
383 * NET_{LOCK,UNLOCK}_GIANT() are not the same as DROP_GIANT()
384 * and PICKUP_GIANT(), as they are plain mutex operations
385 * without a recursion counter.
386 */
387 extern int debug_mpsafenet; /* defined in net/netisr.c */
388 #define NET_LOCK_GIANT() do { \
389 if (!debug_mpsafenet) \
390 mtx_lock(&Giant); \
391 } while (0)
392 #define NET_UNLOCK_GIANT() do { \
393 if (!debug_mpsafenet) \
394 mtx_unlock(&Giant); \
395 } while (0)
396 #define NET_ASSERT_GIANT() do { \
397 if (!debug_mpsafenet) \
398 mtx_assert(&Giant, MA_OWNED); \
399 } while (0)
400 #define NET_CALLOUT_MPSAFE (debug_mpsafenet ? CALLOUT_MPSAFE : 0)
401
402 #define UGAR(rval) do { \
403 int _val = (rval); \
404 mtx_unlock(&Giant); \
405 return (_val); \
406 } while (0)
407
408 struct mtx_args {
409 struct mtx *ma_mtx;
410 const char *ma_desc;
411 int ma_opts;
412 };
413
414 #define MTX_SYSINIT(name, mtx, desc, opts) \
415 static struct mtx_args name##_args = { \
416 (mtx), \
417 (desc), \
418 (opts) \
419 }; \
420 SYSINIT(name##_mtx_sysinit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \
421 mtx_sysinit, &name##_args); \
422 SYSUNINIT(name##_mtx_sysuninit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \
423 mtx_destroy, (mtx))
424
425 /*
426 * The INVARIANTS-enabled mtx_assert() functionality.
427 *
428 * The constants need to be defined for INVARIANT_SUPPORT infrastructure
429 * support as _mtx_assert() itself uses them and the latter implies that
430 * _mtx_assert() must build.
431 */
432 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT)
433 #define MA_OWNED 0x01
434 #define MA_NOTOWNED 0x02
435 #define MA_RECURSED 0x04
436 #define MA_NOTRECURSED 0x08
437 #endif
438
439 #ifdef INVARIANTS
440 #define mtx_assert(m, what) \
441 _mtx_assert((m), (what), __FILE__, __LINE__)
442
443 #define GIANT_REQUIRED mtx_assert(&Giant, MA_OWNED)
444
445 #else /* INVARIANTS */
446 #define mtx_assert(m, what)
447 #define GIANT_REQUIRED
448 #endif /* INVARIANTS */
449
450 /*
451 * Common lock type names.
452 */
453 #define MTX_NETWORK_LOCK "network driver"
454
455 #endif /* _KERNEL */
456 #endif /* !LOCORE */
457 #endif /* _SYS_MUTEX_H_ */
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