source: rtems-libbsd/freebsd/sys/sys/sx.h @ 66659ff

4.1155-freebsd-126-freebsd-12freebsd-9.3
Last change on this file since 66659ff was 66659ff, checked in by Sebastian Huber <sebastian.huber@…>, on 11/06/13 at 15:20:21

Update to FreeBSD 9.2
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File size: 11.4 KB
Line 
1/*-
2 * Copyright (c) 2007 Attilio Rao <attilio@freebsd.org>
3 * Copyright (c) 2001 Jason Evans <jasone@freebsd.org>
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice(s), this list of conditions and the following disclaimer as
11 *    the first lines of this file unmodified other than the possible
12 *    addition of one or more copyright notices.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice(s), this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
18 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
19 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
20 * DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
21 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
22 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
23 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
24 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
27 * DAMAGE.
28 *
29 * $FreeBSD$
30 */
31
32#ifndef _SYS_SX_H_
33#define _SYS_SX_H_
34
35#include <sys/_lock.h>
36#include <sys/_sx.h>
37
38#ifdef  _KERNEL
39#include <sys/pcpu.h>
40#include <sys/lock_profile.h>
41#include <sys/lockstat.h>
42#include <machine/atomic.h>
43#endif
44
45#ifdef __rtems__
46#define SX_NOINLINE 1
47#define _sx_slock _bsd__sx_xlock
48#define _sx_try_slock _bsd__sx_try_xlock
49#define _sx_sunlock _bsd__sx_xunlock
50#endif /* __rtems__ */
51/*
52 * In general, the sx locks and rwlocks use very similar algorithms.
53 * The main difference in the implementations is how threads are
54 * blocked when a lock is unavailable.  For this, sx locks use sleep
55 * queues which do not support priority propagation, and rwlocks use
56 * turnstiles which do.
57 *
58 * The sx_lock field consists of several fields.  The low bit
59 * indicates if the lock is locked with a shared or exclusive lock.  A
60 * value of 0 indicates an exclusive lock, and a value of 1 indicates
61 * a shared lock.  Bit 1 is a boolean indicating if there are any
62 * threads waiting for a shared lock.  Bit 2 is a boolean indicating
63 * if there are any threads waiting for an exclusive lock.  Bit 3 is a
64 * boolean indicating if an exclusive lock is recursively held.  The
65 * rest of the variable's definition is dependent on the value of the
66 * first bit.  For an exclusive lock, it is a pointer to the thread
67 * holding the lock, similar to the mtx_lock field of mutexes.  For
68 * shared locks, it is a count of read locks that are held.
69 *
70 * When the lock is not locked by any thread, it is encoded as a
71 * shared lock with zero waiters.
72 */
73
74#define SX_LOCK_SHARED                  0x01
75#define SX_LOCK_SHARED_WAITERS          0x02
76#define SX_LOCK_EXCLUSIVE_WAITERS       0x04
77#define SX_LOCK_RECURSED                0x08
78#define SX_LOCK_FLAGMASK                                                \
79        (SX_LOCK_SHARED | SX_LOCK_SHARED_WAITERS |                      \
80        SX_LOCK_EXCLUSIVE_WAITERS | SX_LOCK_RECURSED)
81
82#define SX_OWNER(x)                     ((x) & ~SX_LOCK_FLAGMASK)
83#define SX_SHARERS_SHIFT                4
84#define SX_SHARERS(x)                   (SX_OWNER(x) >> SX_SHARERS_SHIFT)
85#define SX_SHARERS_LOCK(x)                                              \
86        ((x) << SX_SHARERS_SHIFT | SX_LOCK_SHARED)
87#define SX_ONE_SHARER                   (1 << SX_SHARERS_SHIFT)
88
89#define SX_LOCK_UNLOCKED                SX_SHARERS_LOCK(0)
90#define SX_LOCK_DESTROYED                                               \
91        (SX_LOCK_SHARED_WAITERS | SX_LOCK_EXCLUSIVE_WAITERS)
92
93#ifdef _KERNEL
94
95/*
96 * Function prototipes.  Routines that start with an underscore are not part
97 * of the public interface and are wrappered with a macro.
98 */
99void    sx_sysinit(void *arg);
100#define sx_init(sx, desc)       sx_init_flags((sx), (desc), 0)
101void    sx_init_flags(struct sx *sx, const char *description, int opts);
102void    sx_destroy(struct sx *sx);
103int     _sx_slock(struct sx *sx, int opts, const char *file, int line);
104int     _sx_xlock(struct sx *sx, int opts, const char *file, int line);
105int     _sx_try_slock(struct sx *sx, const char *file, int line);
106int     _sx_try_xlock(struct sx *sx, const char *file, int line);
107void    _sx_sunlock(struct sx *sx, const char *file, int line);
108void    _sx_xunlock(struct sx *sx, const char *file, int line);
109int     _sx_try_upgrade(struct sx *sx, const char *file, int line);
110void    _sx_downgrade(struct sx *sx, const char *file, int line);
111int     _sx_xlock_hard(struct sx *sx, uintptr_t tid, int opts,
112            const char *file, int line);
113int     _sx_slock_hard(struct sx *sx, int opts, const char *file, int line);
114void    _sx_xunlock_hard(struct sx *sx, uintptr_t tid, const char *file, int
115            line);
116void    _sx_sunlock_hard(struct sx *sx, const char *file, int line);
117#if defined(INVARIANTS) || defined(INVARIANT_SUPPORT)
118void    _sx_assert(struct sx *sx, int what, const char *file, int line);
119#endif
120#ifdef DDB
121int     sx_chain(struct thread *td, struct thread **ownerp);
122#endif
123
124#define sx_downgrade_(sx, file, line)                                   \
125        _sx_downgrade((sx), (file), (line))
126#define sx_try_slock_(sx, file, line)                                   \
127        _sx_try_slock((sx), (file), (line))
128#define sx_try_xlock_(sx, file, line)                                   \
129        _sx_try_xlock((sx), (file), (line))
130#define sx_try_upgrade_(sx, file, line)                                 \
131        _sx_try_upgrade((sx), (file), (line))
132
133struct sx_args {
134        struct sx       *sa_sx;
135        const char      *sa_desc;
136        int             sa_flags;
137};
138
139#define SX_SYSINIT_FLAGS(name, sxa, desc, flags)                        \
140        static struct sx_args name##_args = {                           \
141                (sxa),                                                  \
142                (desc),                                                 \
143                (flags)                                                 \
144        };                                                              \
145        SYSINIT(name##_sx_sysinit, SI_SUB_LOCK, SI_ORDER_MIDDLE,        \
146            sx_sysinit, &name##_args);                                  \
147        SYSUNINIT(name##_sx_sysuninit, SI_SUB_LOCK, SI_ORDER_MIDDLE,    \
148            sx_destroy, (sxa))
149
150#define SX_SYSINIT(name, sxa, desc)     SX_SYSINIT_FLAGS(name, sxa, desc, 0)
151
152#ifndef __rtems__
153/*
154 * Full lock operations that are suitable to be inlined in non-debug kernels.
155 * If the lock can't be acquired or released trivially then the work is
156 * deferred to 'tougher' functions.
157 */
158
159/* Acquire an exclusive lock. */
160static __inline int
161__sx_xlock(struct sx *sx, struct thread *td, int opts, const char *file,
162    int line)
163{
164        uintptr_t tid = (uintptr_t)td;
165        int error = 0;
166
167        if (!atomic_cmpset_acq_ptr(&sx->sx_lock, SX_LOCK_UNLOCKED, tid))
168                error = _sx_xlock_hard(sx, tid, opts, file, line);
169        else
170                LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_SX_XLOCK_ACQUIRE,
171                    sx, 0, 0, file, line);
172
173        return (error);
174}
175
176/* Release an exclusive lock. */
177static __inline void
178__sx_xunlock(struct sx *sx, struct thread *td, const char *file, int line)
179{
180        uintptr_t tid = (uintptr_t)td;
181
182        if (!atomic_cmpset_rel_ptr(&sx->sx_lock, tid, SX_LOCK_UNLOCKED))
183                _sx_xunlock_hard(sx, tid, file, line);
184}
185
186/* Acquire a shared lock. */
187static __inline int
188__sx_slock(struct sx *sx, int opts, const char *file, int line)
189{
190        uintptr_t x = sx->sx_lock;
191        int error = 0;
192
193        if (!(x & SX_LOCK_SHARED) ||
194            !atomic_cmpset_acq_ptr(&sx->sx_lock, x, x + SX_ONE_SHARER))
195                error = _sx_slock_hard(sx, opts, file, line);
196        else
197                LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_SX_SLOCK_ACQUIRE, sx, 0,
198                    0, file, line);
199
200        return (error);
201}
202
203/*
204 * Release a shared lock.  We can just drop a single shared lock so
205 * long as we aren't trying to drop the last shared lock when other
206 * threads are waiting for an exclusive lock.  This takes advantage of
207 * the fact that an unlocked lock is encoded as a shared lock with a
208 * count of 0.
209 */
210static __inline void
211__sx_sunlock(struct sx *sx, const char *file, int line)
212{
213        uintptr_t x = sx->sx_lock;
214
215        if (x == (SX_SHARERS_LOCK(1) | SX_LOCK_EXCLUSIVE_WAITERS) ||
216            !atomic_cmpset_rel_ptr(&sx->sx_lock, x, x - SX_ONE_SHARER))
217                _sx_sunlock_hard(sx, file, line);
218}
219#endif /* __rtems__ */
220
221/*
222 * Public interface for lock operations.
223 */
224#ifndef LOCK_DEBUG
225#error  "LOCK_DEBUG not defined, include <sys/lock.h> before <sys/sx.h>"
226#endif
227#if     (LOCK_DEBUG > 0) || defined(SX_NOINLINE)
228#define sx_xlock_(sx, file, line)                                       \
229        (void)_sx_xlock((sx), 0, (file), (line))
230#define sx_xlock_sig_(sx, file, line)                                   \
231        _sx_xlock((sx), SX_INTERRUPTIBLE, (file), (line))
232#define sx_xunlock_(sx, file, line)                                     \
233        _sx_xunlock((sx), (file), (line))
234#define sx_slock_(sx, file, line)                                       \
235        (void)_sx_slock((sx), 0, (file), (line))
236#define sx_slock_sig_(sx, file, line)                                   \
237        _sx_slock((sx), SX_INTERRUPTIBLE, (file) , (line))
238#define sx_sunlock_(sx, file, line)                                     \
239        _sx_sunlock((sx), (file), (line))
240#else
241#define sx_xlock_(sx, file, line)                                       \
242        (void)__sx_xlock((sx), curthread, 0, (file), (line))
243#define sx_xlock_sig_(sx, file, line)                                   \
244        __sx_xlock((sx), curthread, SX_INTERRUPTIBLE, (file), (line))
245#define sx_xunlock_(sx, file, line)                                     \
246        __sx_xunlock((sx), curthread, (file), (line))
247#define sx_slock_(sx, file, line)                                       \
248        (void)__sx_slock((sx), 0, (file), (line))
249#define sx_slock_sig_(sx, file, line)                                   \
250        __sx_slock((sx), SX_INTERRUPTIBLE, (file), (line))
251#define sx_sunlock_(sx, file, line)                                     \
252        __sx_sunlock((sx), (file), (line))
253#endif  /* LOCK_DEBUG > 0 || SX_NOINLINE */
254#define sx_try_slock(sx)        sx_try_slock_((sx), LOCK_FILE, LOCK_LINE)
255#define sx_try_xlock(sx)        sx_try_xlock_((sx), LOCK_FILE, LOCK_LINE)
256#define sx_try_upgrade(sx)      sx_try_upgrade_((sx), LOCK_FILE, LOCK_LINE)
257#define sx_downgrade(sx)        sx_downgrade_((sx), LOCK_FILE, LOCK_LINE)
258#ifdef INVARIANTS
259#define sx_assert_(sx, what, file, line)                                \
260        _sx_assert((sx), (what), (file), (line))
261#else
262#define sx_assert_(sx, what, file, line)        (void)0
263#endif
264
265#define sx_xlock(sx)            sx_xlock_((sx), LOCK_FILE, LOCK_LINE)
266#define sx_xlock_sig(sx)        sx_xlock_sig_((sx), LOCK_FILE, LOCK_LINE)
267#define sx_xunlock(sx)          sx_xunlock_((sx), LOCK_FILE, LOCK_LINE)
268#define sx_slock(sx)            sx_slock_((sx), LOCK_FILE, LOCK_LINE)
269#define sx_slock_sig(sx)        sx_slock_sig_((sx), LOCK_FILE, LOCK_LINE)
270#define sx_sunlock(sx)          sx_sunlock_((sx), LOCK_FILE, LOCK_LINE)
271#define sx_assert(sx, what)     sx_assert_((sx), (what), __FILE__, __LINE__)
272
273/*
274 * Return a pointer to the owning thread if the lock is exclusively
275 * locked.
276 */
277#ifndef __rtems__
278#define sx_xholder(sx)                                                  \
279        ((sx)->sx_lock & SX_LOCK_SHARED ? NULL :                        \
280        (struct thread *)SX_OWNER((sx)->sx_lock))
281
282#define sx_xlocked(sx)                                                  \
283        (((sx)->sx_lock & ~(SX_LOCK_FLAGMASK & ~SX_LOCK_SHARED)) ==     \
284            (uintptr_t)curthread)
285#else /* __rtems__ */
286int sx_xlocked(struct sx *sx);
287#endif /* __rtems__ */
288
289#define sx_unlock_(sx, file, line) do {                                 \
290        if (sx_xlocked(sx))                                             \
291                sx_xunlock_(sx, file, line);                            \
292        else                                                            \
293                sx_sunlock_(sx, file, line);                            \
294} while (0)
295
296#define sx_unlock(sx)   sx_unlock_((sx), LOCK_FILE, LOCK_LINE)
297
298#define sx_sleep(chan, sx, pri, wmesg, timo)                            \
299        _sleep((chan), &(sx)->lock_object, (pri), (wmesg), (timo))
300
301/*
302 * Options passed to sx_init_flags().
303 */
304#define SX_DUPOK                0x01
305#define SX_NOPROFILE            0x02
306#define SX_NOWITNESS            0x04
307#define SX_QUIET                0x08
308#define SX_NOADAPTIVE           0x10
309#define SX_RECURSE              0x20
310
311/*
312 * Options passed to sx_*lock_hard().
313 */
314#define SX_INTERRUPTIBLE        0x40
315
316#if defined(INVARIANTS) || defined(INVARIANT_SUPPORT)
317#define SA_LOCKED               LA_LOCKED
318#define SA_SLOCKED              LA_SLOCKED
319#define SA_XLOCKED              LA_XLOCKED
320#define SA_UNLOCKED             LA_UNLOCKED
321#define SA_RECURSED             LA_RECURSED
322#define SA_NOTRECURSED          LA_NOTRECURSED
323
324/* Backwards compatability. */
325#define SX_LOCKED               LA_LOCKED
326#define SX_SLOCKED              LA_SLOCKED
327#define SX_XLOCKED              LA_XLOCKED
328#define SX_UNLOCKED             LA_UNLOCKED
329#define SX_RECURSED             LA_RECURSED
330#define SX_NOTRECURSED          LA_NOTRECURSED
331#endif
332
333#endif /* _KERNEL */
334
335#endif /* !_SYS_SX_H_ */
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