]>
Commit | Line | Data |
---|---|---|
6e35fa2d VG |
1 | /* |
2 | * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License version 2 as | |
6 | * published by the Free Software Foundation. | |
7 | */ | |
8 | ||
9 | #ifndef __ASM_SPINLOCK_H | |
10 | #define __ASM_SPINLOCK_H | |
11 | ||
12 | #include <asm/spinlock_types.h> | |
13 | #include <asm/processor.h> | |
14 | #include <asm/barrier.h> | |
15 | ||
16 | #define arch_spin_is_locked(x) ((x)->slock != __ARCH_SPIN_LOCK_UNLOCKED__) | |
17 | #define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock) | |
726328d9 PZ |
18 | |
19 | static inline void arch_spin_unlock_wait(arch_spinlock_t *lock) | |
20 | { | |
21 | smp_cond_load_acquire(&lock->slock, !VAL); | |
22 | } | |
6e35fa2d | 23 | |
ae7eae9e VG |
24 | #ifdef CONFIG_ARC_HAS_LLSC |
25 | ||
26 | static inline void arch_spin_lock(arch_spinlock_t *lock) | |
27 | { | |
28 | unsigned int val; | |
29 | ||
30 | smp_mb(); | |
31 | ||
32 | __asm__ __volatile__( | |
33 | "1: llock %[val], [%[slock]] \n" | |
34 | " breq %[val], %[LOCKED], 1b \n" /* spin while LOCKED */ | |
35 | " scond %[LOCKED], [%[slock]] \n" /* acquire */ | |
36 | " bnz 1b \n" | |
37 | " \n" | |
38 | : [val] "=&r" (val) | |
39 | : [slock] "r" (&(lock->slock)), | |
40 | [LOCKED] "r" (__ARCH_SPIN_LOCK_LOCKED__) | |
41 | : "memory", "cc"); | |
42 | ||
43 | smp_mb(); | |
44 | } | |
45 | ||
46 | /* 1 - lock taken successfully */ | |
47 | static inline int arch_spin_trylock(arch_spinlock_t *lock) | |
48 | { | |
49 | unsigned int val, got_it = 0; | |
50 | ||
51 | smp_mb(); | |
52 | ||
53 | __asm__ __volatile__( | |
54 | "1: llock %[val], [%[slock]] \n" | |
55 | " breq %[val], %[LOCKED], 4f \n" /* already LOCKED, just bail */ | |
56 | " scond %[LOCKED], [%[slock]] \n" /* acquire */ | |
57 | " bnz 1b \n" | |
58 | " mov %[got_it], 1 \n" | |
59 | "4: \n" | |
60 | " \n" | |
61 | : [val] "=&r" (val), | |
62 | [got_it] "+&r" (got_it) | |
63 | : [slock] "r" (&(lock->slock)), | |
64 | [LOCKED] "r" (__ARCH_SPIN_LOCK_LOCKED__) | |
65 | : "memory", "cc"); | |
66 | ||
67 | smp_mb(); | |
68 | ||
69 | return got_it; | |
70 | } | |
71 | ||
72 | static inline void arch_spin_unlock(arch_spinlock_t *lock) | |
73 | { | |
74 | smp_mb(); | |
75 | ||
76 | lock->slock = __ARCH_SPIN_LOCK_UNLOCKED__; | |
77 | ||
78 | smp_mb(); | |
79 | } | |
80 | ||
69cbe630 VG |
81 | /* |
82 | * Read-write spinlocks, allowing multiple readers but only one writer. | |
83 | * Unfair locking as Writers could be starved indefinitely by Reader(s) | |
84 | */ | |
85 | ||
86 | static inline void arch_read_lock(arch_rwlock_t *rw) | |
87 | { | |
88 | unsigned int val; | |
89 | ||
90 | smp_mb(); | |
91 | ||
92 | /* | |
93 | * zero means writer holds the lock exclusively, deny Reader. | |
94 | * Otherwise grant lock to first/subseq reader | |
95 | * | |
96 | * if (rw->counter > 0) { | |
97 | * rw->counter--; | |
98 | * ret = 1; | |
99 | * } | |
100 | */ | |
101 | ||
102 | __asm__ __volatile__( | |
103 | "1: llock %[val], [%[rwlock]] \n" | |
104 | " brls %[val], %[WR_LOCKED], 1b\n" /* <= 0: spin while write locked */ | |
105 | " sub %[val], %[val], 1 \n" /* reader lock */ | |
106 | " scond %[val], [%[rwlock]] \n" | |
107 | " bnz 1b \n" | |
108 | " \n" | |
109 | : [val] "=&r" (val) | |
110 | : [rwlock] "r" (&(rw->counter)), | |
111 | [WR_LOCKED] "ir" (0) | |
112 | : "memory", "cc"); | |
113 | ||
114 | smp_mb(); | |
115 | } | |
116 | ||
117 | /* 1 - lock taken successfully */ | |
118 | static inline int arch_read_trylock(arch_rwlock_t *rw) | |
119 | { | |
120 | unsigned int val, got_it = 0; | |
121 | ||
122 | smp_mb(); | |
123 | ||
124 | __asm__ __volatile__( | |
125 | "1: llock %[val], [%[rwlock]] \n" | |
126 | " brls %[val], %[WR_LOCKED], 4f\n" /* <= 0: already write locked, bail */ | |
127 | " sub %[val], %[val], 1 \n" /* counter-- */ | |
128 | " scond %[val], [%[rwlock]] \n" | |
129 | " bnz 1b \n" /* retry if collided with someone */ | |
130 | " mov %[got_it], 1 \n" | |
131 | " \n" | |
132 | "4: ; --- done --- \n" | |
133 | ||
134 | : [val] "=&r" (val), | |
135 | [got_it] "+&r" (got_it) | |
136 | : [rwlock] "r" (&(rw->counter)), | |
137 | [WR_LOCKED] "ir" (0) | |
138 | : "memory", "cc"); | |
139 | ||
140 | smp_mb(); | |
141 | ||
142 | return got_it; | |
143 | } | |
144 | ||
145 | static inline void arch_write_lock(arch_rwlock_t *rw) | |
146 | { | |
147 | unsigned int val; | |
148 | ||
149 | smp_mb(); | |
150 | ||
151 | /* | |
152 | * If reader(s) hold lock (lock < __ARCH_RW_LOCK_UNLOCKED__), | |
153 | * deny writer. Otherwise if unlocked grant to writer | |
154 | * Hence the claim that Linux rwlocks are unfair to writers. | |
155 | * (can be starved for an indefinite time by readers). | |
156 | * | |
157 | * if (rw->counter == __ARCH_RW_LOCK_UNLOCKED__) { | |
158 | * rw->counter = 0; | |
159 | * ret = 1; | |
160 | * } | |
161 | */ | |
162 | ||
163 | __asm__ __volatile__( | |
164 | "1: llock %[val], [%[rwlock]] \n" | |
165 | " brne %[val], %[UNLOCKED], 1b \n" /* while !UNLOCKED spin */ | |
166 | " mov %[val], %[WR_LOCKED] \n" | |
167 | " scond %[val], [%[rwlock]] \n" | |
168 | " bnz 1b \n" | |
169 | " \n" | |
170 | : [val] "=&r" (val) | |
171 | : [rwlock] "r" (&(rw->counter)), | |
172 | [UNLOCKED] "ir" (__ARCH_RW_LOCK_UNLOCKED__), | |
173 | [WR_LOCKED] "ir" (0) | |
174 | : "memory", "cc"); | |
175 | ||
176 | smp_mb(); | |
177 | } | |
178 | ||
179 | /* 1 - lock taken successfully */ | |
180 | static inline int arch_write_trylock(arch_rwlock_t *rw) | |
181 | { | |
182 | unsigned int val, got_it = 0; | |
183 | ||
184 | smp_mb(); | |
185 | ||
186 | __asm__ __volatile__( | |
187 | "1: llock %[val], [%[rwlock]] \n" | |
188 | " brne %[val], %[UNLOCKED], 4f \n" /* !UNLOCKED, bail */ | |
189 | " mov %[val], %[WR_LOCKED] \n" | |
190 | " scond %[val], [%[rwlock]] \n" | |
191 | " bnz 1b \n" /* retry if collided with someone */ | |
192 | " mov %[got_it], 1 \n" | |
193 | " \n" | |
194 | "4: ; --- done --- \n" | |
195 | ||
196 | : [val] "=&r" (val), | |
197 | [got_it] "+&r" (got_it) | |
198 | : [rwlock] "r" (&(rw->counter)), | |
199 | [UNLOCKED] "ir" (__ARCH_RW_LOCK_UNLOCKED__), | |
200 | [WR_LOCKED] "ir" (0) | |
201 | : "memory", "cc"); | |
202 | ||
203 | smp_mb(); | |
204 | ||
205 | return got_it; | |
206 | } | |
207 | ||
208 | static inline void arch_read_unlock(arch_rwlock_t *rw) | |
209 | { | |
210 | unsigned int val; | |
211 | ||
212 | smp_mb(); | |
213 | ||
214 | /* | |
215 | * rw->counter++; | |
216 | */ | |
217 | __asm__ __volatile__( | |
218 | "1: llock %[val], [%[rwlock]] \n" | |
219 | " add %[val], %[val], 1 \n" | |
220 | " scond %[val], [%[rwlock]] \n" | |
221 | " bnz 1b \n" | |
222 | " \n" | |
223 | : [val] "=&r" (val) | |
224 | : [rwlock] "r" (&(rw->counter)) | |
225 | : "memory", "cc"); | |
226 | ||
227 | smp_mb(); | |
228 | } | |
229 | ||
230 | static inline void arch_write_unlock(arch_rwlock_t *rw) | |
231 | { | |
232 | smp_mb(); | |
233 | ||
234 | rw->counter = __ARCH_RW_LOCK_UNLOCKED__; | |
235 | ||
236 | smp_mb(); | |
237 | } | |
238 | ||
ae7eae9e VG |
239 | #else /* !CONFIG_ARC_HAS_LLSC */ |
240 | ||
6e35fa2d VG |
241 | static inline void arch_spin_lock(arch_spinlock_t *lock) |
242 | { | |
ae7eae9e | 243 | unsigned int val = __ARCH_SPIN_LOCK_LOCKED__; |
6e35fa2d | 244 | |
2576c28e VG |
245 | /* |
246 | * This smp_mb() is technically superfluous, we only need the one | |
247 | * after the lock for providing the ACQUIRE semantics. | |
248 | * However doing the "right" thing was regressing hackbench | |
249 | * so keeping this, pending further investigation | |
250 | */ | |
251 | smp_mb(); | |
252 | ||
6e35fa2d VG |
253 | __asm__ __volatile__( |
254 | "1: ex %0, [%1] \n" | |
255 | " breq %0, %2, 1b \n" | |
ae7eae9e | 256 | : "+&r" (val) |
6e35fa2d VG |
257 | : "r"(&(lock->slock)), "ir"(__ARCH_SPIN_LOCK_LOCKED__) |
258 | : "memory"); | |
2576c28e VG |
259 | |
260 | /* | |
261 | * ACQUIRE barrier to ensure load/store after taking the lock | |
262 | * don't "bleed-up" out of the critical section (leak-in is allowed) | |
263 | * http://www.spinics.net/lists/kernel/msg2010409.html | |
264 | * | |
265 | * ARCv2 only has load-load, store-store and all-all barrier | |
266 | * thus need the full all-all barrier | |
267 | */ | |
268 | smp_mb(); | |
6e35fa2d VG |
269 | } |
270 | ||
ae7eae9e | 271 | /* 1 - lock taken successfully */ |
6e35fa2d VG |
272 | static inline int arch_spin_trylock(arch_spinlock_t *lock) |
273 | { | |
ae7eae9e | 274 | unsigned int val = __ARCH_SPIN_LOCK_LOCKED__; |
6e35fa2d | 275 | |
2576c28e VG |
276 | smp_mb(); |
277 | ||
6e35fa2d VG |
278 | __asm__ __volatile__( |
279 | "1: ex %0, [%1] \n" | |
ae7eae9e | 280 | : "+r" (val) |
6e35fa2d VG |
281 | : "r"(&(lock->slock)) |
282 | : "memory"); | |
283 | ||
2576c28e VG |
284 | smp_mb(); |
285 | ||
ae7eae9e | 286 | return (val == __ARCH_SPIN_LOCK_UNLOCKED__); |
6e35fa2d VG |
287 | } |
288 | ||
289 | static inline void arch_spin_unlock(arch_spinlock_t *lock) | |
290 | { | |
ae7eae9e | 291 | unsigned int val = __ARCH_SPIN_LOCK_UNLOCKED__; |
6c00350b | 292 | |
2576c28e VG |
293 | /* |
294 | * RELEASE barrier: given the instructions avail on ARCv2, full barrier | |
295 | * is the only option | |
296 | */ | |
297 | smp_mb(); | |
298 | ||
6c00350b VG |
299 | __asm__ __volatile__( |
300 | " ex %0, [%1] \n" | |
ae7eae9e | 301 | : "+r" (val) |
6c00350b VG |
302 | : "r"(&(lock->slock)) |
303 | : "memory"); | |
304 | ||
2576c28e VG |
305 | /* |
306 | * superfluous, but keeping for now - see pairing version in | |
307 | * arch_spin_lock above | |
308 | */ | |
6e35fa2d VG |
309 | smp_mb(); |
310 | } | |
311 | ||
312 | /* | |
313 | * Read-write spinlocks, allowing multiple readers but only one writer. | |
69cbe630 | 314 | * Unfair locking as Writers could be starved indefinitely by Reader(s) |
6e35fa2d VG |
315 | * |
316 | * The spinlock itself is contained in @counter and access to it is | |
317 | * serialized with @lock_mutex. | |
6e35fa2d VG |
318 | */ |
319 | ||
6e35fa2d VG |
320 | /* 1 - lock taken successfully */ |
321 | static inline int arch_read_trylock(arch_rwlock_t *rw) | |
322 | { | |
323 | int ret = 0; | |
2a1021fc | 324 | unsigned long flags; |
6e35fa2d | 325 | |
2a1021fc | 326 | local_irq_save(flags); |
6e35fa2d VG |
327 | arch_spin_lock(&(rw->lock_mutex)); |
328 | ||
329 | /* | |
330 | * zero means writer holds the lock exclusively, deny Reader. | |
331 | * Otherwise grant lock to first/subseq reader | |
332 | */ | |
333 | if (rw->counter > 0) { | |
334 | rw->counter--; | |
335 | ret = 1; | |
336 | } | |
337 | ||
338 | arch_spin_unlock(&(rw->lock_mutex)); | |
2a1021fc | 339 | local_irq_restore(flags); |
6e35fa2d VG |
340 | |
341 | smp_mb(); | |
342 | return ret; | |
343 | } | |
344 | ||
345 | /* 1 - lock taken successfully */ | |
346 | static inline int arch_write_trylock(arch_rwlock_t *rw) | |
347 | { | |
348 | int ret = 0; | |
2a1021fc | 349 | unsigned long flags; |
6e35fa2d | 350 | |
2a1021fc | 351 | local_irq_save(flags); |
6e35fa2d VG |
352 | arch_spin_lock(&(rw->lock_mutex)); |
353 | ||
354 | /* | |
355 | * If reader(s) hold lock (lock < __ARCH_RW_LOCK_UNLOCKED__), | |
356 | * deny writer. Otherwise if unlocked grant to writer | |
357 | * Hence the claim that Linux rwlocks are unfair to writers. | |
358 | * (can be starved for an indefinite time by readers). | |
359 | */ | |
360 | if (rw->counter == __ARCH_RW_LOCK_UNLOCKED__) { | |
361 | rw->counter = 0; | |
362 | ret = 1; | |
363 | } | |
364 | arch_spin_unlock(&(rw->lock_mutex)); | |
2a1021fc | 365 | local_irq_restore(flags); |
6e35fa2d VG |
366 | |
367 | return ret; | |
368 | } | |
369 | ||
370 | static inline void arch_read_lock(arch_rwlock_t *rw) | |
371 | { | |
372 | while (!arch_read_trylock(rw)) | |
373 | cpu_relax(); | |
374 | } | |
375 | ||
376 | static inline void arch_write_lock(arch_rwlock_t *rw) | |
377 | { | |
378 | while (!arch_write_trylock(rw)) | |
379 | cpu_relax(); | |
380 | } | |
381 | ||
382 | static inline void arch_read_unlock(arch_rwlock_t *rw) | |
383 | { | |
2a1021fc NC |
384 | unsigned long flags; |
385 | ||
386 | local_irq_save(flags); | |
6e35fa2d VG |
387 | arch_spin_lock(&(rw->lock_mutex)); |
388 | rw->counter++; | |
389 | arch_spin_unlock(&(rw->lock_mutex)); | |
2a1021fc | 390 | local_irq_restore(flags); |
6e35fa2d VG |
391 | } |
392 | ||
393 | static inline void arch_write_unlock(arch_rwlock_t *rw) | |
394 | { | |
2a1021fc NC |
395 | unsigned long flags; |
396 | ||
397 | local_irq_save(flags); | |
6e35fa2d VG |
398 | arch_spin_lock(&(rw->lock_mutex)); |
399 | rw->counter = __ARCH_RW_LOCK_UNLOCKED__; | |
400 | arch_spin_unlock(&(rw->lock_mutex)); | |
2a1021fc | 401 | local_irq_restore(flags); |
6e35fa2d VG |
402 | } |
403 | ||
69cbe630 VG |
404 | #endif |
405 | ||
406 | #define arch_read_can_lock(x) ((x)->counter > 0) | |
407 | #define arch_write_can_lock(x) ((x)->counter == __ARCH_RW_LOCK_UNLOCKED__) | |
408 | ||
6e35fa2d VG |
409 | #define arch_read_lock_flags(lock, flags) arch_read_lock(lock) |
410 | #define arch_write_lock_flags(lock, flags) arch_write_lock(lock) | |
411 | ||
412 | #define arch_spin_relax(lock) cpu_relax() | |
413 | #define arch_read_relax(lock) cpu_relax() | |
414 | #define arch_write_relax(lock) cpu_relax() | |
415 | ||
416 | #endif /* __ASM_SPINLOCK_H */ |