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/5.0/sys/sys/mutex.h 100754 2002-07-27 16:54:23Z 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 can also be
53 * 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 #define MTX_SLEEPABLE 0x00000010 /* We can sleep with this lock. */
60 #define MTX_DUPOK 0x00000020 /* Don't log a duplicate acquire */
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
68 /*
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.
71 */
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)
76
77 #endif /* _KERNEL */
78
79 #ifndef LOCORE
80
81 /*
82 * XXX: Friendly reminder to fix things in MP code that is presently being
83 * XXX: worked on.
84 */
85 #define mp_fixme(string)
86
87 #ifdef _KERNEL
88
89 /*
90 * Prototypes
91 *
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.
96 *
97 * [See below for descriptions]
98 *
99 */
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,
112 int line);
113 void _mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file,
114 int line);
115 #ifdef INVARIANT_SUPPORT
116 void _mtx_assert(struct mtx *m, int what, const char *file, int line);
117 #endif
118 int mtx_lock_giant(int sysctlvar);
119 void mtx_unlock_giant(int s);
120
121 /*
122 * We define our machine-independent (unoptimized) mutex micro-operations
123 * here, if they are not already defined in the machine-dependent mutex.h
124 */
125
126 /* Actually obtain mtx_lock */
127 #ifndef _obtain_lock
128 #define _obtain_lock(mp, tid) \
129 atomic_cmpset_acq_ptr(&(mp)->mtx_lock, (void *)MTX_UNOWNED, (tid))
130 #endif
131
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)
136 #endif
137
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)
142 #endif
143
144 /*
145 * Obtain a sleep lock inline, or call the "hard" function if we can't get it
146 * easy.
147 */
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)); \
152 } while (0)
153 #endif
154
155 /*
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
160 * a deal.
161 */
162 #ifndef _get_spin_lock
163 #define _get_spin_lock(mp, tid, opts, file, line) do { \
164 critical_enter(); \
165 if (!_obtain_lock((mp), (tid))) { \
166 if ((mp)->mtx_lock == (uintptr_t)(tid)) \
167 (mp)->mtx_recurse++; \
168 else \
169 _mtx_lock_spin((mp), (opts), (file), (line)); \
170 } \
171 } while (0)
172 #endif
173
174 /*
175 * Release a sleep lock inline, or call the "hard" function if we can't do it
176 * easy.
177 */
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)); \
182 } while (0)
183 #endif
184
185 /*
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
189 * a deal.
190 *
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.
194 */
195 #ifndef _rel_spin_lock
196 #define _rel_spin_lock(mp) do { \
197 if (mtx_recursed((mp))) \
198 (mp)->mtx_recurse--; \
199 else \
200 _release_lock_quick((mp)); \
201 critical_exit(); \
202 } while (0)
203 #endif
204
205 /*
206 * Exported lock manipulation interface.
207 *
208 * mtx_lock(m) locks MTX_DEF mutex `m'
209 *
210 * mtx_lock_spin(m) locks MTX_SPIN mutex `m'
211 *
212 * mtx_unlock(m) unlocks MTX_DEF mutex `m'
213 *
214 * mtx_unlock_spin(m) unlocks MTX_SPIN mutex `m'
215 *
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.
220 *
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
225 * is _not_ recursed.
226 *
227 * mtx_trylock_flags(m, opts) is used the same way as mtx_trylock() but accepts
228 * relevant option flags `opts.'
229 *
230 * mtx_initialized(m) returns non-zero if the lock `m' has been initialized.
231 *
232 * mtx_owned(m) returns non-zero if the current thread owns the lock `m'
233 *
234 * mtx_recursed(m) returns non-zero if the lock `m' is presently recursed.
235 */
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)
241
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);
246
247 extern int mtx_pool_valid;
248
249 #ifndef LOCK_DEBUG
250 #error LOCK_DEBUG not defined, include <sys/lock.h> before <sys/mutex.h>
251 #endif
252 #if LOCK_DEBUG > 0
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)
266 #ifndef SMPnotyet
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) \
270 _rel_spin_lock((m))
271 #else /* SMP */
272 #define mtx_lock_spin_flags(m, opts) critical_enter()
273 #define mtx_unlock_spin_flags(m, opts) critical_exit()
274 #endif /* SMP */
275 #endif /* LOCK_DEBUG */
276
277 #define mtx_trylock_flags(m, opts) \
278 _mtx_trylock((m), (opts), LOCK_FILE, LOCK_LINE)
279
280 #define mtx_initialized(m) ((m)->mtx_object.lo_flags & LO_INITIALIZED)
281
282 #define mtx_owned(m) (((m)->mtx_lock & MTX_FLAGMASK) == (uintptr_t)curthread)
283
284 #define mtx_recursed(m) ((m)->mtx_recurse != 0)
285
286 #define mtx_name(m) ((m)->mtx_object.lo_name)
287
288 /*
289 * Global locks.
290 */
291 extern struct mtx sched_lock;
292 extern struct mtx Giant;
293
294 /*
295 * Giant lock sysctl variables used by other modules
296 */
297 extern int kern_giant_proc;
298 extern int kern_giant_file;
299 extern int kern_giant_ucred;
300
301 /*
302 * Giant lock manipulation and clean exit macros.
303 * Used to replace return with an exit Giant and return.
304 *
305 * Note that DROP_GIANT*() needs to be paired with PICKUP_GIANT()
306 */
307 #define DROP_GIANT() \
308 do { \
309 int _giantcnt; \
310 WITNESS_SAVE_DECL(Giant); \
311 \
312 if (mtx_owned(&Giant)) \
313 WITNESS_SAVE(&Giant.mtx_object, Giant); \
314 for (_giantcnt = 0; mtx_owned(&Giant); _giantcnt++) \
315 mtx_unlock(&Giant)
316
317 #define PICKUP_GIANT() \
318 mtx_assert(&Giant, MA_NOTOWNED); \
319 while (_giantcnt--) \
320 mtx_lock(&Giant); \
321 if (mtx_owned(&Giant)) \
322 WITNESS_RESTORE(&Giant.mtx_object, Giant); \
323 } while (0)
324
325 #define PARTIAL_PICKUP_GIANT() \
326 mtx_assert(&Giant, MA_NOTOWNED); \
327 while (_giantcnt--) \
328 mtx_lock(&Giant); \
329 if (mtx_owned(&Giant)) \
330 WITNESS_RESTORE(&Giant.mtx_object, Giant)
331
332 #define UGAR(rval) do { \
333 int _val = (rval); \
334 mtx_unlock(&Giant); \
335 return (_val); \
336 } while (0)
337
338 struct mtx_args {
339 struct mtx *ma_mtx;
340 const char *ma_desc;
341 int ma_opts;
342 };
343
344 #define MTX_SYSINIT(name, mtx, desc, opts) \
345 static struct mtx_args name##_args = { \
346 mtx, \
347 desc, \
348 opts \
349 }; \
350 SYSINIT(name##_mtx_sysinit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \
351 mtx_sysinit, &name##_args)
352
353 /*
354 * The INVARIANTS-enabled mtx_assert() functionality.
355 *
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.
359 */
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 */
366
367 #ifdef INVARIANTS
368 #define mtx_assert(m, what) \
369 _mtx_assert((m), (what), __FILE__, __LINE__)
370
371 #define GIANT_REQUIRED mtx_assert(&Giant, MA_OWNED)
372
373 #else /* INVARIANTS */
374 #define mtx_assert(m, what)
375 #define GIANT_REQUIRED
376 #endif /* INVARIANTS */
377
378 /*
379 * Common lock type names.
380 */
381 #define MTX_NETWORK_LOCK "network driver"
382
383 #endif /* _KERNEL */
384 #endif /* !LOCORE */
385 #endif /* _SYS_MUTEX_H_ */
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