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. */
62 * Option flags passed to certain lock/unlock routines, through the use
63 * of corresponding mtx_{lock,unlock}_flags() interface macros.
65 #define MTX_QUIET LOP_QUIET /* Don't log a mutex event */
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.
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)
81 * XXX: Friendly reminder to fix things in MP code that is presently being
84 #define mp_fixme(string)
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.
96 * [See below for descriptions]
99 void mtx_init(struct mtx *m, const char *description, int opts);
100 void mtx_destroy(struct mtx *m);
101 void _mtx_lock_sleep(struct mtx *m, int opts, const char *file, int line);
102 void _mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line);
103 void _mtx_lock_spin(struct mtx *m, int opts, const char *file, int line);
104 void _mtx_unlock_spin(struct mtx *m, int opts, const char *file, int line);
105 int _mtx_trylock(struct mtx *m, int opts, const char *file, int line);
106 void _mtx_lock_flags(struct mtx *m, int opts, const char *file, int line);
107 void _mtx_unlock_flags(struct mtx *m, int opts, const char *file, int line);
108 void _mtx_lock_spin_flags(struct mtx *m, int opts, const char *file,
110 void _mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file,
112 #ifdef INVARIANT_SUPPORT
113 void _mtx_assert(struct mtx *m, int what, const char *file, int line);
115 int mtx_lock_giant(int sysctlvar);
116 void mtx_unlock_giant(int s);
119 * We define our machine-independent (unoptimized) mutex micro-operations
120 * here, if they are not already defined in the machine-dependent mutex.h
123 /* Actually obtain mtx_lock */
125 #define _obtain_lock(mp, tid) \
126 atomic_cmpset_acq_ptr(&(mp)->mtx_lock, (void *)MTX_UNOWNED, (tid))
129 /* Actually release mtx_lock */
130 #ifndef _release_lock
131 #define _release_lock(mp, tid) \
132 atomic_cmpset_rel_ptr(&(mp)->mtx_lock, (tid), (void *)MTX_UNOWNED)
135 /* Actually release mtx_lock quickly, assuming we own it. */
136 #ifndef _release_lock_quick
137 #define _release_lock_quick(mp) \
138 atomic_store_rel_ptr(&(mp)->mtx_lock, (void *)MTX_UNOWNED)
142 * Obtain a sleep lock inline, or call the "hard" function if we can't get it
145 #ifndef _get_sleep_lock
146 #define _get_sleep_lock(mp, tid, opts, file, line) do { \
147 if (!_obtain_lock((mp), (tid))) \
148 _mtx_lock_sleep((mp), (opts), (file), (line)); \
153 * Obtain a spin lock inline, or call the "hard" function if we can't get it
154 * easy. For spinlocks, we handle recursion inline (it turns out that function
155 * calls can be significantly expensive on some architectures).
156 * Since spin locks are not _too_ common, inlining this code is not too big
159 #ifndef _get_spin_lock
160 #define _get_spin_lock(mp, tid, opts, file, line) do { \
162 if (!_obtain_lock((mp), (tid))) { \
163 if ((mp)->mtx_lock == (uintptr_t)(tid)) \
164 (mp)->mtx_recurse++; \
166 _mtx_lock_spin((mp), (opts), (file), (line)); \
172 * Release a sleep lock inline, or call the "hard" function if we can't do it
175 #ifndef _rel_sleep_lock
176 #define _rel_sleep_lock(mp, tid, opts, file, line) do { \
177 if (!_release_lock((mp), (tid))) \
178 _mtx_unlock_sleep((mp), (opts), (file), (line)); \
183 * For spinlocks, we can handle everything inline, as it's pretty simple and
184 * a function call would be too expensive (at least on some architectures).
185 * Since spin locks are not _too_ common, inlining this code is not too big
188 * Since we always perform a critical_enter() when attempting to acquire a
189 * spin lock, we need to always perform a matching critical_exit() when
190 * releasing a spin lock. This includes the recursion cases.
192 #ifndef _rel_spin_lock
193 #define _rel_spin_lock(mp) do { \
194 if (mtx_recursed((mp))) \
195 (mp)->mtx_recurse--; \
197 _release_lock_quick((mp)); \
203 * Exported lock manipulation interface.
205 * mtx_lock(m) locks MTX_DEF mutex `m'
207 * mtx_lock_spin(m) locks MTX_SPIN mutex `m'
209 * mtx_unlock(m) unlocks MTX_DEF mutex `m'
211 * mtx_unlock_spin(m) unlocks MTX_SPIN mutex `m'
213 * mtx_lock_spin_flags(m, opts) and mtx_lock_flags(m, opts) locks mutex `m'
214 * and passes option flags `opts' to the "hard" function, if required.
215 * With these routines, it is possible to pass flags such as MTX_QUIET
216 * to the appropriate lock manipulation routines.
218 * mtx_trylock(m) attempts to acquire MTX_DEF mutex `m' but doesn't sleep if
219 * it cannot. Rather, it returns 0 on failure and non-zero on success.
220 * It does NOT handle recursion as we assume that if a caller is properly
221 * using this part of the interface, he will know that the lock in question
224 * mtx_trylock_flags(m, opts) is used the same way as mtx_trylock() but accepts
225 * relevant option flags `opts.'
227 * mtx_initialized(m) returns non-zero if the lock `m' has been initialized.
229 * mtx_owned(m) returns non-zero if the current thread owns the lock `m'
231 * mtx_recursed(m) returns non-zero if the lock `m' is presently recursed.
233 #define mtx_lock(m) mtx_lock_flags((m), 0)
234 #define mtx_lock_spin(m) mtx_lock_spin_flags((m), 0)
235 #define mtx_trylock(m) mtx_trylock_flags((m), 0)
236 #define mtx_unlock(m) mtx_unlock_flags((m), 0)
237 #define mtx_unlock_spin(m) mtx_unlock_spin_flags((m), 0)
239 struct mtx *mtx_pool_find(void *ptr);
240 struct mtx *mtx_pool_alloc(void);
241 void mtx_pool_lock(void *ptr);
242 void mtx_pool_unlock(void *ptr);
244 extern int mtx_pool_valid;
247 #error LOCK_DEBUG not defined, include <sys/lock.h> before <sys/mutex.h>
250 #define mtx_lock_flags(m, opts) \
251 _mtx_lock_flags((m), (opts), LOCK_FILE, LOCK_LINE)
252 #define mtx_unlock_flags(m, opts) \
253 _mtx_unlock_flags((m), (opts), LOCK_FILE, LOCK_LINE)
254 #define mtx_lock_spin_flags(m, opts) \
255 _mtx_lock_spin_flags((m), (opts), LOCK_FILE, LOCK_LINE)
256 #define mtx_unlock_spin_flags(m, opts) \
257 _mtx_unlock_spin_flags((m), (opts), LOCK_FILE, LOCK_LINE)
259 #define mtx_lock_flags(m, opts) \
260 _get_sleep_lock((m), curthread, (opts), LOCK_FILE, LOCK_LINE)
261 #define mtx_unlock_flags(m, opts) \
262 _rel_sleep_lock((m), curthread, (opts), LOCK_FILE, LOCK_LINE)
263 #define mtx_lock_spin_flags(m, opts) \
264 _get_spin_lock((m), curthread, (opts), LOCK_FILE, LOCK_LINE)
265 #define mtx_unlock_spin_flags(m, opts) \
269 #define mtx_trylock_flags(m, opts) \
270 _mtx_trylock((m), (opts), LOCK_FILE, LOCK_LINE)
272 #define mtx_initialized(m) ((m)->mtx_object.lo_flags & LO_INITIALIZED)
274 #define mtx_owned(m) (((m)->mtx_lock & MTX_FLAGMASK) == (uintptr_t)curthread)
276 #define mtx_recursed(m) ((m)->mtx_recurse != 0)
281 extern struct mtx sched_lock;
282 extern struct mtx Giant;
285 * Giant lock sysctl variables used by other modules
287 extern int kern_giant_proc;
288 extern int kern_giant_file;
289 extern int kern_giant_ucred;
292 * Giant lock manipulation and clean exit macros.
293 * Used to replace return with an exit Giant and return.
295 * Note that DROP_GIANT*() needs to be paired with PICKUP_GIANT()
297 #define DROP_GIANT() \
300 WITNESS_SAVE_DECL(Giant); \
302 if (mtx_owned(&Giant)) \
303 WITNESS_SAVE(&Giant.mtx_object, Giant); \
304 for (_giantcnt = 0; mtx_owned(&Giant); _giantcnt++) \
307 #define PICKUP_GIANT() \
308 mtx_assert(&Giant, MA_NOTOWNED); \
309 while (_giantcnt--) \
311 if (mtx_owned(&Giant)) \
312 WITNESS_RESTORE(&Giant.mtx_object, Giant); \
315 #define PARTIAL_PICKUP_GIANT() \
316 mtx_assert(&Giant, MA_NOTOWNED); \
317 while (_giantcnt--) \
319 if (mtx_owned(&Giant)) \
320 WITNESS_RESTORE(&Giant.mtx_object, Giant)
322 #define UGAR(rval) do { \
324 mtx_unlock(&Giant); \
329 * The INVARIANTS-enabled mtx_assert() functionality.
331 * The constants need to be defined for INVARIANT_SUPPORT infrastructure
332 * support as _mtx_assert() itself uses them and the latter implies that
333 * _mtx_assert() must build.
335 #ifdef INVARIANT_SUPPORT
336 #define MA_OWNED 0x01
337 #define MA_NOTOWNED 0x02
338 #define MA_RECURSED 0x04
339 #define MA_NOTRECURSED 0x08
340 #endif /* INVARIANT_SUPPORT */
343 #define mtx_assert(m, what) \
344 _mtx_assert((m), (what), __FILE__, __LINE__)
346 #define GIANT_REQUIRED mtx_assert(&Giant, MA_OWNED)
348 #else /* INVARIANTS */
349 #define mtx_assert(m, what)
350 #define GIANT_REQUIRED
351 #endif /* INVARIANTS */
355 #endif /* _SYS_MUTEX_H_ */