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5ac4a56b GKH |
1 | /* |
2 | Unix SMB/CIFS implementation. | |
3 | Samba database functions | |
4 | Copyright (C) Anton Blanchard 2001 | |
5 | ||
6 | This program is free software; you can redistribute it and/or modify | |
7 | it under the terms of the GNU General Public License as published by | |
8 | the Free Software Foundation; either version 2 of the License, or | |
9 | (at your option) any later version. | |
10 | ||
11 | This program is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | GNU General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
17 | along with this program; if not, write to the Free Software | |
18 | Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
19 | */ | |
20 | #if HAVE_CONFIG_H | |
21 | #include <config.h> | |
22 | #endif | |
23 | ||
24 | #if STANDALONE | |
25 | #include <stdlib.h> | |
26 | #include <stdio.h> | |
27 | #include <unistd.h> | |
28 | #include <string.h> | |
29 | #include <fcntl.h> | |
30 | #include <errno.h> | |
31 | #include <sys/stat.h> | |
32 | #include <time.h> | |
33 | #include <signal.h> | |
34 | #include "tdb.h" | |
35 | #include "spinlock.h" | |
36 | ||
37 | #define DEBUG | |
38 | #else | |
39 | #include "includes.h" | |
40 | #endif | |
41 | ||
42 | #ifdef USE_SPINLOCKS | |
43 | ||
44 | /* | |
45 | * ARCH SPECIFIC | |
46 | */ | |
47 | ||
48 | #if defined(SPARC_SPINLOCKS) | |
49 | ||
50 | static inline int __spin_trylock(spinlock_t *lock) | |
51 | { | |
52 | unsigned int result; | |
53 | ||
54 | asm volatile("ldstub [%1], %0" | |
55 | : "=r" (result) | |
56 | : "r" (lock) | |
57 | : "memory"); | |
58 | ||
59 | return (result == 0) ? 0 : EBUSY; | |
60 | } | |
61 | ||
62 | static inline void __spin_unlock(spinlock_t *lock) | |
63 | { | |
64 | asm volatile("":::"memory"); | |
65 | *lock = 0; | |
66 | } | |
67 | ||
68 | static inline void __spin_lock_init(spinlock_t *lock) | |
69 | { | |
70 | *lock = 0; | |
71 | } | |
72 | ||
73 | static inline int __spin_is_locked(spinlock_t *lock) | |
74 | { | |
75 | return (*lock != 0); | |
76 | } | |
77 | ||
78 | #elif defined(POWERPC_SPINLOCKS) | |
79 | ||
80 | static inline int __spin_trylock(spinlock_t *lock) | |
81 | { | |
82 | unsigned int result; | |
83 | ||
84 | __asm__ __volatile__( | |
85 | "1: lwarx %0,0,%1\n\ | |
86 | cmpwi 0,%0,0\n\ | |
87 | li %0,0\n\ | |
88 | bne- 2f\n\ | |
89 | li %0,1\n\ | |
90 | stwcx. %0,0,%1\n\ | |
91 | bne- 1b\n\ | |
92 | isync\n\ | |
93 | 2:" : "=&r"(result) | |
94 | : "r"(lock) | |
95 | : "cr0", "memory"); | |
96 | ||
97 | return (result == 1) ? 0 : EBUSY; | |
98 | } | |
99 | ||
100 | static inline void __spin_unlock(spinlock_t *lock) | |
101 | { | |
102 | asm volatile("eieio":::"memory"); | |
103 | *lock = 0; | |
104 | } | |
105 | ||
106 | static inline void __spin_lock_init(spinlock_t *lock) | |
107 | { | |
108 | *lock = 0; | |
109 | } | |
110 | ||
111 | static inline int __spin_is_locked(spinlock_t *lock) | |
112 | { | |
113 | return (*lock != 0); | |
114 | } | |
115 | ||
116 | #elif defined(INTEL_SPINLOCKS) | |
117 | ||
118 | static inline int __spin_trylock(spinlock_t *lock) | |
119 | { | |
120 | int oldval; | |
121 | ||
122 | asm volatile("xchgl %0,%1" | |
123 | : "=r" (oldval), "=m" (*lock) | |
124 | : "0" (0) | |
125 | : "memory"); | |
126 | ||
127 | return oldval > 0 ? 0 : EBUSY; | |
128 | } | |
129 | ||
130 | static inline void __spin_unlock(spinlock_t *lock) | |
131 | { | |
132 | asm volatile("":::"memory"); | |
133 | *lock = 1; | |
134 | } | |
135 | ||
136 | static inline void __spin_lock_init(spinlock_t *lock) | |
137 | { | |
138 | *lock = 1; | |
139 | } | |
140 | ||
141 | static inline int __spin_is_locked(spinlock_t *lock) | |
142 | { | |
143 | return (*lock != 1); | |
144 | } | |
145 | ||
146 | #elif defined(MIPS_SPINLOCKS) | |
147 | ||
148 | static inline unsigned int load_linked(unsigned long addr) | |
149 | { | |
150 | unsigned int res; | |
151 | ||
152 | __asm__ __volatile__("ll\t%0,(%1)" | |
153 | : "=r" (res) | |
154 | : "r" (addr)); | |
155 | ||
156 | return res; | |
157 | } | |
158 | ||
159 | static inline unsigned int store_conditional(unsigned long addr, unsigned int value) | |
160 | { | |
161 | unsigned int res; | |
162 | ||
163 | __asm__ __volatile__("sc\t%0,(%2)" | |
164 | : "=r" (res) | |
165 | : "0" (value), "r" (addr)); | |
166 | return res; | |
167 | } | |
168 | ||
169 | static inline int __spin_trylock(spinlock_t *lock) | |
170 | { | |
171 | unsigned int mw; | |
172 | ||
173 | do { | |
174 | mw = load_linked(lock); | |
175 | if (mw) | |
176 | return EBUSY; | |
177 | } while (!store_conditional(lock, 1)); | |
178 | ||
179 | asm volatile("":::"memory"); | |
180 | ||
181 | return 0; | |
182 | } | |
183 | ||
184 | static inline void __spin_unlock(spinlock_t *lock) | |
185 | { | |
186 | asm volatile("":::"memory"); | |
187 | *lock = 0; | |
188 | } | |
189 | ||
190 | static inline void __spin_lock_init(spinlock_t *lock) | |
191 | { | |
192 | *lock = 0; | |
193 | } | |
194 | ||
195 | static inline int __spin_is_locked(spinlock_t *lock) | |
196 | { | |
197 | return (*lock != 0); | |
198 | } | |
199 | ||
200 | #else | |
201 | #error Need to implement spinlock code in spinlock.c | |
202 | #endif | |
203 | ||
204 | /* | |
205 | * OS SPECIFIC | |
206 | */ | |
207 | ||
208 | static void yield_cpu(void) | |
209 | { | |
210 | struct timespec tm; | |
211 | ||
212 | #ifdef USE_SCHED_YIELD | |
213 | sched_yield(); | |
214 | #else | |
215 | /* Linux will busy loop for delays < 2ms on real time tasks */ | |
216 | tm.tv_sec = 0; | |
217 | tm.tv_nsec = 2000000L + 1; | |
218 | nanosleep(&tm, NULL); | |
219 | #endif | |
220 | } | |
221 | ||
222 | static int this_is_smp(void) | |
223 | { | |
224 | return 0; | |
225 | } | |
226 | ||
227 | /* | |
228 | * GENERIC | |
229 | */ | |
230 | ||
231 | static int smp_machine = 0; | |
232 | ||
233 | static inline void __spin_lock(spinlock_t *lock) | |
234 | { | |
235 | int ntries = 0; | |
236 | ||
237 | while(__spin_trylock(lock)) { | |
238 | while(__spin_is_locked(lock)) { | |
239 | if (smp_machine && ntries++ < MAX_BUSY_LOOPS) | |
240 | continue; | |
241 | yield_cpu(); | |
242 | } | |
243 | } | |
244 | } | |
245 | ||
246 | static void __read_lock(tdb_rwlock_t *rwlock) | |
247 | { | |
248 | int ntries = 0; | |
249 | ||
250 | while(1) { | |
251 | __spin_lock(&rwlock->lock); | |
252 | ||
253 | if (!(rwlock->count & RWLOCK_BIAS)) { | |
254 | rwlock->count++; | |
255 | __spin_unlock(&rwlock->lock); | |
256 | return; | |
257 | } | |
258 | ||
259 | __spin_unlock(&rwlock->lock); | |
260 | ||
261 | while(rwlock->count & RWLOCK_BIAS) { | |
262 | if (smp_machine && ntries++ < MAX_BUSY_LOOPS) | |
263 | continue; | |
264 | yield_cpu(); | |
265 | } | |
266 | } | |
267 | } | |
268 | ||
269 | static void __write_lock(tdb_rwlock_t *rwlock) | |
270 | { | |
271 | int ntries = 0; | |
272 | ||
273 | while(1) { | |
274 | __spin_lock(&rwlock->lock); | |
275 | ||
276 | if (rwlock->count == 0) { | |
277 | rwlock->count |= RWLOCK_BIAS; | |
278 | __spin_unlock(&rwlock->lock); | |
279 | return; | |
280 | } | |
281 | ||
282 | __spin_unlock(&rwlock->lock); | |
283 | ||
284 | while(rwlock->count != 0) { | |
285 | if (smp_machine && ntries++ < MAX_BUSY_LOOPS) | |
286 | continue; | |
287 | yield_cpu(); | |
288 | } | |
289 | } | |
290 | } | |
291 | ||
292 | static void __write_unlock(tdb_rwlock_t *rwlock) | |
293 | { | |
294 | __spin_lock(&rwlock->lock); | |
295 | ||
296 | #ifdef DEBUG | |
297 | if (!(rwlock->count & RWLOCK_BIAS)) | |
298 | fprintf(stderr, "bug: write_unlock\n"); | |
299 | #endif | |
300 | ||
301 | rwlock->count &= ~RWLOCK_BIAS; | |
302 | __spin_unlock(&rwlock->lock); | |
303 | } | |
304 | ||
305 | static void __read_unlock(tdb_rwlock_t *rwlock) | |
306 | { | |
307 | __spin_lock(&rwlock->lock); | |
308 | ||
309 | #ifdef DEBUG | |
310 | if (!rwlock->count) | |
311 | fprintf(stderr, "bug: read_unlock\n"); | |
312 | ||
313 | if (rwlock->count & RWLOCK_BIAS) | |
314 | fprintf(stderr, "bug: read_unlock\n"); | |
315 | #endif | |
316 | ||
317 | rwlock->count--; | |
318 | __spin_unlock(&rwlock->lock); | |
319 | } | |
320 | ||
321 | /* TDB SPECIFIC */ | |
322 | ||
323 | /* lock a list in the database. list -1 is the alloc list */ | |
324 | int tdb_spinlock(TDB_CONTEXT *tdb, int list, int rw_type) | |
325 | { | |
326 | tdb_rwlock_t *rwlocks; | |
327 | ||
328 | if (!tdb->map_ptr) return -1; | |
329 | rwlocks = (tdb_rwlock_t *)((char *)tdb->map_ptr + tdb->header.rwlocks); | |
330 | ||
331 | switch(rw_type) { | |
332 | case F_RDLCK: | |
333 | __read_lock(&rwlocks[list+1]); | |
334 | break; | |
335 | ||
336 | case F_WRLCK: | |
337 | __write_lock(&rwlocks[list+1]); | |
338 | break; | |
339 | ||
340 | default: | |
341 | return TDB_ERRCODE(TDB_ERR_LOCK, -1); | |
342 | } | |
343 | return 0; | |
344 | } | |
345 | ||
346 | /* unlock the database. */ | |
347 | int tdb_spinunlock(TDB_CONTEXT *tdb, int list, int rw_type) | |
348 | { | |
349 | tdb_rwlock_t *rwlocks; | |
350 | ||
351 | if (!tdb->map_ptr) return -1; | |
352 | rwlocks = (tdb_rwlock_t *)((char *)tdb->map_ptr + tdb->header.rwlocks); | |
353 | ||
354 | switch(rw_type) { | |
355 | case F_RDLCK: | |
356 | __read_unlock(&rwlocks[list+1]); | |
357 | break; | |
358 | ||
359 | case F_WRLCK: | |
360 | __write_unlock(&rwlocks[list+1]); | |
361 | break; | |
362 | ||
363 | default: | |
364 | return TDB_ERRCODE(TDB_ERR_LOCK, -1); | |
365 | } | |
366 | ||
367 | return 0; | |
368 | } | |
369 | ||
370 | int tdb_create_rwlocks(int fd, unsigned int hash_size) | |
371 | { | |
372 | unsigned size, i; | |
373 | tdb_rwlock_t *rwlocks; | |
374 | ||
375 | size = (hash_size + 1) * sizeof(tdb_rwlock_t); | |
376 | rwlocks = malloc(size); | |
377 | if (!rwlocks) | |
378 | return -1; | |
379 | ||
380 | for(i = 0; i < hash_size+1; i++) { | |
381 | __spin_lock_init(&rwlocks[i].lock); | |
382 | rwlocks[i].count = 0; | |
383 | } | |
384 | ||
385 | /* Write it out (appending to end) */ | |
386 | if (write(fd, rwlocks, size) != size) { | |
387 | free(rwlocks); | |
388 | return -1; | |
389 | } | |
390 | smp_machine = this_is_smp(); | |
391 | free(rwlocks); | |
392 | return 0; | |
393 | } | |
394 | ||
395 | int tdb_clear_spinlocks(TDB_CONTEXT *tdb) | |
396 | { | |
397 | tdb_rwlock_t *rwlocks; | |
398 | unsigned i; | |
399 | ||
400 | if (tdb->header.rwlocks == 0) return 0; | |
401 | if (!tdb->map_ptr) return -1; | |
402 | ||
403 | /* We're mmapped here */ | |
404 | rwlocks = (tdb_rwlock_t *)((char *)tdb->map_ptr + tdb->header.rwlocks); | |
405 | for(i = 0; i < tdb->header.hash_size+1; i++) { | |
406 | __spin_lock_init(&rwlocks[i].lock); | |
407 | rwlocks[i].count = 0; | |
408 | } | |
409 | return 0; | |
410 | } | |
411 | #else | |
412 | int tdb_create_rwlocks(int fd, unsigned int hash_size) { return 0; } | |
413 | int tdb_spinlock(TDB_CONTEXT *tdb, int list, int rw_type) { return -1; } | |
414 | int tdb_spinunlock(TDB_CONTEXT *tdb, int list, int rw_type) { return -1; } | |
415 | ||
416 | /* Non-spinlock version: remove spinlock pointer */ | |
417 | int tdb_clear_spinlocks(TDB_CONTEXT *tdb) | |
418 | { | |
419 | tdb_off off = (tdb_off)((char *)&tdb->header.rwlocks | |
420 | - (char *)&tdb->header); | |
421 | ||
422 | tdb->header.rwlocks = 0; | |
423 | if (lseek(tdb->fd, off, SEEK_SET) != off | |
424 | || write(tdb->fd, (void *)&tdb->header.rwlocks, | |
425 | sizeof(tdb->header.rwlocks)) | |
426 | != sizeof(tdb->header.rwlocks)) | |
427 | return -1; | |
428 | return 0; | |
429 | } | |
430 | #endif |