Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | #ifndef _S390_RWSEM_H |
2 | #define _S390_RWSEM_H | |
3 | ||
4 | /* | |
5 | * include/asm-s390/rwsem.h | |
6 | * | |
7 | * S390 version | |
8 | * Copyright (C) 2002 IBM Deutschland Entwicklung GmbH, IBM Corporation | |
9 | * Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com) | |
10 | * | |
11 | * Based on asm-alpha/semaphore.h and asm-i386/rwsem.h | |
12 | */ | |
13 | ||
14 | /* | |
15 | * | |
16 | * The MSW of the count is the negated number of active writers and waiting | |
17 | * lockers, and the LSW is the total number of active locks | |
18 | * | |
19 | * The lock count is initialized to 0 (no active and no waiting lockers). | |
20 | * | |
21 | * When a writer subtracts WRITE_BIAS, it'll get 0xffff0001 for the case of an | |
22 | * uncontended lock. This can be determined because XADD returns the old value. | |
23 | * Readers increment by 1 and see a positive value when uncontended, negative | |
24 | * if there are writers (and maybe) readers waiting (in which case it goes to | |
25 | * sleep). | |
26 | * | |
27 | * The value of WAITING_BIAS supports up to 32766 waiting processes. This can | |
28 | * be extended to 65534 by manually checking the whole MSW rather than relying | |
29 | * on the S flag. | |
30 | * | |
31 | * The value of ACTIVE_BIAS supports up to 65535 active processes. | |
32 | * | |
33 | * This should be totally fair - if anything is waiting, a process that wants a | |
34 | * lock will go to the back of the queue. When the currently active lock is | |
35 | * released, if there's a writer at the front of the queue, then that and only | |
36 | * that will be woken up; if there's a bunch of consequtive readers at the | |
37 | * front, then they'll all be woken up, but no other readers will be. | |
38 | */ | |
39 | ||
40 | #ifndef _LINUX_RWSEM_H | |
41 | #error "please don't include asm/rwsem.h directly, use linux/rwsem.h instead" | |
42 | #endif | |
43 | ||
44 | #ifdef __KERNEL__ | |
45 | ||
46 | #include <linux/list.h> | |
47 | #include <linux/spinlock.h> | |
48 | ||
49 | struct rwsem_waiter; | |
50 | ||
51 | extern struct rw_semaphore *rwsem_down_read_failed(struct rw_semaphore *); | |
52 | extern struct rw_semaphore *rwsem_down_write_failed(struct rw_semaphore *); | |
53 | extern struct rw_semaphore *rwsem_wake(struct rw_semaphore *); | |
54 | extern struct rw_semaphore *rwsem_downgrade_wake(struct rw_semaphore *); | |
55 | extern struct rw_semaphore *rwsem_downgrade_write(struct rw_semaphore *); | |
56 | ||
57 | /* | |
58 | * the semaphore definition | |
59 | */ | |
60 | struct rw_semaphore { | |
61 | signed long count; | |
62 | spinlock_t wait_lock; | |
63 | struct list_head wait_list; | |
64 | }; | |
65 | ||
66 | #ifndef __s390x__ | |
67 | #define RWSEM_UNLOCKED_VALUE 0x00000000 | |
68 | #define RWSEM_ACTIVE_BIAS 0x00000001 | |
69 | #define RWSEM_ACTIVE_MASK 0x0000ffff | |
70 | #define RWSEM_WAITING_BIAS (-0x00010000) | |
71 | #else /* __s390x__ */ | |
72 | #define RWSEM_UNLOCKED_VALUE 0x0000000000000000L | |
73 | #define RWSEM_ACTIVE_BIAS 0x0000000000000001L | |
74 | #define RWSEM_ACTIVE_MASK 0x00000000ffffffffL | |
75 | #define RWSEM_WAITING_BIAS (-0x0000000100000000L) | |
76 | #endif /* __s390x__ */ | |
77 | #define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS | |
78 | #define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS) | |
79 | ||
80 | /* | |
81 | * initialisation | |
82 | */ | |
83 | #define __RWSEM_INITIALIZER(name) \ | |
84 | { RWSEM_UNLOCKED_VALUE, SPIN_LOCK_UNLOCKED, LIST_HEAD_INIT((name).wait_list) } | |
85 | ||
86 | #define DECLARE_RWSEM(name) \ | |
87 | struct rw_semaphore name = __RWSEM_INITIALIZER(name) | |
88 | ||
89 | static inline void init_rwsem(struct rw_semaphore *sem) | |
90 | { | |
91 | sem->count = RWSEM_UNLOCKED_VALUE; | |
92 | spin_lock_init(&sem->wait_lock); | |
93 | INIT_LIST_HEAD(&sem->wait_list); | |
94 | } | |
95 | ||
96 | /* | |
97 | * lock for reading | |
98 | */ | |
99 | static inline void __down_read(struct rw_semaphore *sem) | |
100 | { | |
101 | signed long old, new; | |
102 | ||
103 | __asm__ __volatile__( | |
104 | #ifndef __s390x__ | |
105 | " l %0,0(%3)\n" | |
106 | "0: lr %1,%0\n" | |
107 | " ahi %1,%5\n" | |
108 | " cs %0,%1,0(%3)\n" | |
109 | " jl 0b" | |
110 | #else /* __s390x__ */ | |
111 | " lg %0,0(%3)\n" | |
112 | "0: lgr %1,%0\n" | |
113 | " aghi %1,%5\n" | |
114 | " csg %0,%1,0(%3)\n" | |
115 | " jl 0b" | |
116 | #endif /* __s390x__ */ | |
117 | : "=&d" (old), "=&d" (new), "=m" (sem->count) | |
118 | : "a" (&sem->count), "m" (sem->count), | |
119 | "i" (RWSEM_ACTIVE_READ_BIAS) : "cc", "memory" ); | |
120 | if (old < 0) | |
121 | rwsem_down_read_failed(sem); | |
122 | } | |
123 | ||
124 | /* | |
125 | * trylock for reading -- returns 1 if successful, 0 if contention | |
126 | */ | |
127 | static inline int __down_read_trylock(struct rw_semaphore *sem) | |
128 | { | |
129 | signed long old, new; | |
130 | ||
131 | __asm__ __volatile__( | |
132 | #ifndef __s390x__ | |
133 | " l %0,0(%3)\n" | |
134 | "0: ltr %1,%0\n" | |
135 | " jm 1f\n" | |
136 | " ahi %1,%5\n" | |
137 | " cs %0,%1,0(%3)\n" | |
138 | " jl 0b\n" | |
139 | "1:" | |
140 | #else /* __s390x__ */ | |
141 | " lg %0,0(%3)\n" | |
142 | "0: ltgr %1,%0\n" | |
143 | " jm 1f\n" | |
144 | " aghi %1,%5\n" | |
145 | " csg %0,%1,0(%3)\n" | |
146 | " jl 0b\n" | |
147 | "1:" | |
148 | #endif /* __s390x__ */ | |
149 | : "=&d" (old), "=&d" (new), "=m" (sem->count) | |
150 | : "a" (&sem->count), "m" (sem->count), | |
151 | "i" (RWSEM_ACTIVE_READ_BIAS) : "cc", "memory" ); | |
152 | return old >= 0 ? 1 : 0; | |
153 | } | |
154 | ||
155 | /* | |
156 | * lock for writing | |
157 | */ | |
158 | static inline void __down_write(struct rw_semaphore *sem) | |
159 | { | |
160 | signed long old, new, tmp; | |
161 | ||
162 | tmp = RWSEM_ACTIVE_WRITE_BIAS; | |
163 | __asm__ __volatile__( | |
164 | #ifndef __s390x__ | |
165 | " l %0,0(%3)\n" | |
166 | "0: lr %1,%0\n" | |
167 | " a %1,%5\n" | |
168 | " cs %0,%1,0(%3)\n" | |
169 | " jl 0b" | |
170 | #else /* __s390x__ */ | |
171 | " lg %0,0(%3)\n" | |
172 | "0: lgr %1,%0\n" | |
173 | " ag %1,%5\n" | |
174 | " csg %0,%1,0(%3)\n" | |
175 | " jl 0b" | |
176 | #endif /* __s390x__ */ | |
177 | : "=&d" (old), "=&d" (new), "=m" (sem->count) | |
178 | : "a" (&sem->count), "m" (sem->count), "m" (tmp) | |
179 | : "cc", "memory" ); | |
180 | if (old != 0) | |
181 | rwsem_down_write_failed(sem); | |
182 | } | |
183 | ||
184 | /* | |
185 | * trylock for writing -- returns 1 if successful, 0 if contention | |
186 | */ | |
187 | static inline int __down_write_trylock(struct rw_semaphore *sem) | |
188 | { | |
189 | signed long old; | |
190 | ||
191 | __asm__ __volatile__( | |
192 | #ifndef __s390x__ | |
193 | " l %0,0(%2)\n" | |
194 | "0: ltr %0,%0\n" | |
195 | " jnz 1f\n" | |
196 | " cs %0,%4,0(%2)\n" | |
197 | " jl 0b\n" | |
198 | #else /* __s390x__ */ | |
199 | " lg %0,0(%2)\n" | |
200 | "0: ltgr %0,%0\n" | |
201 | " jnz 1f\n" | |
202 | " csg %0,%4,0(%2)\n" | |
203 | " jl 0b\n" | |
204 | #endif /* __s390x__ */ | |
205 | "1:" | |
206 | : "=&d" (old), "=m" (sem->count) | |
207 | : "a" (&sem->count), "m" (sem->count), | |
208 | "d" (RWSEM_ACTIVE_WRITE_BIAS) : "cc", "memory" ); | |
209 | return (old == RWSEM_UNLOCKED_VALUE) ? 1 : 0; | |
210 | } | |
211 | ||
212 | /* | |
213 | * unlock after reading | |
214 | */ | |
215 | static inline void __up_read(struct rw_semaphore *sem) | |
216 | { | |
217 | signed long old, new; | |
218 | ||
219 | __asm__ __volatile__( | |
220 | #ifndef __s390x__ | |
221 | " l %0,0(%3)\n" | |
222 | "0: lr %1,%0\n" | |
223 | " ahi %1,%5\n" | |
224 | " cs %0,%1,0(%3)\n" | |
225 | " jl 0b" | |
226 | #else /* __s390x__ */ | |
227 | " lg %0,0(%3)\n" | |
228 | "0: lgr %1,%0\n" | |
229 | " aghi %1,%5\n" | |
230 | " csg %0,%1,0(%3)\n" | |
231 | " jl 0b" | |
232 | #endif /* __s390x__ */ | |
233 | : "=&d" (old), "=&d" (new), "=m" (sem->count) | |
234 | : "a" (&sem->count), "m" (sem->count), | |
235 | "i" (-RWSEM_ACTIVE_READ_BIAS) | |
236 | : "cc", "memory" ); | |
237 | if (new < 0) | |
238 | if ((new & RWSEM_ACTIVE_MASK) == 0) | |
239 | rwsem_wake(sem); | |
240 | } | |
241 | ||
242 | /* | |
243 | * unlock after writing | |
244 | */ | |
245 | static inline void __up_write(struct rw_semaphore *sem) | |
246 | { | |
247 | signed long old, new, tmp; | |
248 | ||
249 | tmp = -RWSEM_ACTIVE_WRITE_BIAS; | |
250 | __asm__ __volatile__( | |
251 | #ifndef __s390x__ | |
252 | " l %0,0(%3)\n" | |
253 | "0: lr %1,%0\n" | |
254 | " a %1,%5\n" | |
255 | " cs %0,%1,0(%3)\n" | |
256 | " jl 0b" | |
257 | #else /* __s390x__ */ | |
258 | " lg %0,0(%3)\n" | |
259 | "0: lgr %1,%0\n" | |
260 | " ag %1,%5\n" | |
261 | " csg %0,%1,0(%3)\n" | |
262 | " jl 0b" | |
263 | #endif /* __s390x__ */ | |
264 | : "=&d" (old), "=&d" (new), "=m" (sem->count) | |
265 | : "a" (&sem->count), "m" (sem->count), "m" (tmp) | |
266 | : "cc", "memory" ); | |
267 | if (new < 0) | |
268 | if ((new & RWSEM_ACTIVE_MASK) == 0) | |
269 | rwsem_wake(sem); | |
270 | } | |
271 | ||
272 | /* | |
273 | * downgrade write lock to read lock | |
274 | */ | |
275 | static inline void __downgrade_write(struct rw_semaphore *sem) | |
276 | { | |
277 | signed long old, new, tmp; | |
278 | ||
279 | tmp = -RWSEM_WAITING_BIAS; | |
280 | __asm__ __volatile__( | |
281 | #ifndef __s390x__ | |
282 | " l %0,0(%3)\n" | |
283 | "0: lr %1,%0\n" | |
284 | " a %1,%5\n" | |
285 | " cs %0,%1,0(%3)\n" | |
286 | " jl 0b" | |
287 | #else /* __s390x__ */ | |
288 | " lg %0,0(%3)\n" | |
289 | "0: lgr %1,%0\n" | |
290 | " ag %1,%5\n" | |
291 | " csg %0,%1,0(%3)\n" | |
292 | " jl 0b" | |
293 | #endif /* __s390x__ */ | |
294 | : "=&d" (old), "=&d" (new), "=m" (sem->count) | |
295 | : "a" (&sem->count), "m" (sem->count), "m" (tmp) | |
296 | : "cc", "memory" ); | |
297 | if (new > 1) | |
298 | rwsem_downgrade_wake(sem); | |
299 | } | |
300 | ||
301 | /* | |
302 | * implement atomic add functionality | |
303 | */ | |
304 | static inline void rwsem_atomic_add(long delta, struct rw_semaphore *sem) | |
305 | { | |
306 | signed long old, new; | |
307 | ||
308 | __asm__ __volatile__( | |
309 | #ifndef __s390x__ | |
310 | " l %0,0(%3)\n" | |
311 | "0: lr %1,%0\n" | |
312 | " ar %1,%5\n" | |
313 | " cs %0,%1,0(%3)\n" | |
314 | " jl 0b" | |
315 | #else /* __s390x__ */ | |
316 | " lg %0,0(%3)\n" | |
317 | "0: lgr %1,%0\n" | |
318 | " agr %1,%5\n" | |
319 | " csg %0,%1,0(%3)\n" | |
320 | " jl 0b" | |
321 | #endif /* __s390x__ */ | |
322 | : "=&d" (old), "=&d" (new), "=m" (sem->count) | |
323 | : "a" (&sem->count), "m" (sem->count), "d" (delta) | |
324 | : "cc", "memory" ); | |
325 | } | |
326 | ||
327 | /* | |
328 | * implement exchange and add functionality | |
329 | */ | |
330 | static inline long rwsem_atomic_update(long delta, struct rw_semaphore *sem) | |
331 | { | |
332 | signed long old, new; | |
333 | ||
334 | __asm__ __volatile__( | |
335 | #ifndef __s390x__ | |
336 | " l %0,0(%3)\n" | |
337 | "0: lr %1,%0\n" | |
338 | " ar %1,%5\n" | |
339 | " cs %0,%1,0(%3)\n" | |
340 | " jl 0b" | |
341 | #else /* __s390x__ */ | |
342 | " lg %0,0(%3)\n" | |
343 | "0: lgr %1,%0\n" | |
344 | " agr %1,%5\n" | |
345 | " csg %0,%1,0(%3)\n" | |
346 | " jl 0b" | |
347 | #endif /* __s390x__ */ | |
348 | : "=&d" (old), "=&d" (new), "=m" (sem->count) | |
349 | : "a" (&sem->count), "m" (sem->count), "d" (delta) | |
350 | : "cc", "memory" ); | |
351 | return new; | |
352 | } | |
353 | ||
eb92f4ef RVR |
354 | static inline int rwsem_is_locked(struct rw_semaphore *sem) |
355 | { | |
356 | return (sem->count != 0); | |
357 | } | |
358 | ||
1da177e4 LT |
359 | #endif /* __KERNEL__ */ |
360 | #endif /* _S390_RWSEM_H */ |