2 Unix SMB/CIFS implementation.
4 trivial database library
6 Copyright (C) Anton Blanchard 2001
8 ** NOTE! The following LGPL license applies to the tdb
9 ** library. This does NOT imply that all of Samba is released
12 This library is free software; you can redistribute it and/or
13 modify it under the terms of the GNU Lesser General Public
14 License as published by the Free Software Foundation; either
15 version 2 of the License, or (at your option) any later version.
17 This library is distributed in the hope that it will be useful,
18 but WITHOUT ANY WARRANTY; without even the implied warranty of
19 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20 Lesser General Public License for more details.
22 You should have received a copy of the GNU Lesser General Public
23 License along with this library; if not, write to the Free Software
24 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
54 #if defined(SPARC_SPINLOCKS)
56 static inline int __spin_trylock(spinlock_t
*lock
)
60 asm volatile("ldstub [%1], %0"
65 return (result
== 0) ? 0 : EBUSY
;
68 static inline void __spin_unlock(spinlock_t
*lock
)
70 asm volatile("":::"memory");
74 static inline void __spin_lock_init(spinlock_t
*lock
)
79 static inline int __spin_is_locked(spinlock_t
*lock
)
84 #elif defined(POWERPC_SPINLOCKS)
86 static inline int __spin_trylock(spinlock_t
*lock
)
103 return (result
== 1) ? 0 : EBUSY
;
106 static inline void __spin_unlock(spinlock_t
*lock
)
108 asm volatile("eieio":::"memory");
112 static inline void __spin_lock_init(spinlock_t
*lock
)
117 static inline int __spin_is_locked(spinlock_t
*lock
)
122 #elif defined(INTEL_SPINLOCKS)
124 static inline int __spin_trylock(spinlock_t
*lock
)
128 asm volatile("xchgl %0,%1"
129 : "=r" (oldval
), "=m" (*lock
)
133 return oldval
> 0 ? 0 : EBUSY
;
136 static inline void __spin_unlock(spinlock_t
*lock
)
138 asm volatile("":::"memory");
142 static inline void __spin_lock_init(spinlock_t
*lock
)
147 static inline int __spin_is_locked(spinlock_t
*lock
)
152 #elif defined(MIPS_SPINLOCKS) && defined(sgi) && (_COMPILER_VERSION >= 730)
154 /* Implement spinlocks on IRIX using the MIPSPro atomic fetch operations. See
155 * sync(3) for the details of the intrinsic operations.
157 * "sgi" and "_COMPILER_VERSION" are always defined by MIPSPro.
162 /* MIPSPro 7.3 has "__inline" as an extension, but not "inline. */
163 #define inline __inline
165 #endif /* STANDALONE */
167 /* Returns 0 if the lock is acquired, EBUSY otherwise. */
168 static inline int __spin_trylock(spinlock_t
*lock
)
171 val
= __lock_test_and_set(lock
, 1);
172 return val
== 0 ? 0 : EBUSY
;
175 static inline void __spin_unlock(spinlock_t
*lock
)
177 __lock_release(lock
);
180 static inline void __spin_lock_init(spinlock_t
*lock
)
182 __lock_release(lock
);
185 /* Returns 1 if the lock is held, 0 otherwise. */
186 static inline int __spin_is_locked(spinlock_t
*lock
)
189 val
= __add_and_fetch(lock
, 0);
193 #elif defined(MIPS_SPINLOCKS)
195 static inline unsigned int load_linked(unsigned long addr
)
199 __asm__
__volatile__("ll\t%0,(%1)"
206 static inline unsigned int store_conditional(unsigned long addr
, unsigned int value
)
210 __asm__
__volatile__("sc\t%0,(%2)"
212 : "0" (value
), "r" (addr
));
216 static inline int __spin_trylock(spinlock_t
*lock
)
221 mw
= load_linked(lock
);
224 } while (!store_conditional(lock
, 1));
226 asm volatile("":::"memory");
231 static inline void __spin_unlock(spinlock_t
*lock
)
233 asm volatile("":::"memory");
237 static inline void __spin_lock_init(spinlock_t
*lock
)
242 static inline int __spin_is_locked(spinlock_t
*lock
)
248 #error Need to implement spinlock code in spinlock.c
255 static void yield_cpu(void)
259 #ifdef USE_SCHED_YIELD
262 /* Linux will busy loop for delays < 2ms on real time tasks */
264 tm
.tv_nsec
= 2000000L + 1;
265 nanosleep(&tm
, NULL
);
273 static int smp_machine
= 0;
275 static inline void __spin_lock(spinlock_t
*lock
)
279 while(__spin_trylock(lock
)) {
280 while(__spin_is_locked(lock
)) {
281 if (smp_machine
&& ntries
++ < MAX_BUSY_LOOPS
)
288 static void __read_lock(tdb_rwlock_t
*rwlock
)
293 __spin_lock(&rwlock
->lock
);
295 if (!(rwlock
->count
& RWLOCK_BIAS
)) {
297 __spin_unlock(&rwlock
->lock
);
301 __spin_unlock(&rwlock
->lock
);
303 while(rwlock
->count
& RWLOCK_BIAS
) {
304 if (smp_machine
&& ntries
++ < MAX_BUSY_LOOPS
)
311 static void __write_lock(tdb_rwlock_t
*rwlock
)
316 __spin_lock(&rwlock
->lock
);
318 if (rwlock
->count
== 0) {
319 rwlock
->count
|= RWLOCK_BIAS
;
320 __spin_unlock(&rwlock
->lock
);
324 __spin_unlock(&rwlock
->lock
);
326 while(rwlock
->count
!= 0) {
327 if (smp_machine
&& ntries
++ < MAX_BUSY_LOOPS
)
334 static void __write_unlock(tdb_rwlock_t
*rwlock
)
336 __spin_lock(&rwlock
->lock
);
339 if (!(rwlock
->count
& RWLOCK_BIAS
))
340 fprintf(stderr
, "bug: write_unlock\n");
343 rwlock
->count
&= ~RWLOCK_BIAS
;
344 __spin_unlock(&rwlock
->lock
);
347 static void __read_unlock(tdb_rwlock_t
*rwlock
)
349 __spin_lock(&rwlock
->lock
);
353 fprintf(stderr
, "bug: read_unlock\n");
355 if (rwlock
->count
& RWLOCK_BIAS
)
356 fprintf(stderr
, "bug: read_unlock\n");
360 __spin_unlock(&rwlock
->lock
);
365 /* lock a list in the database. list -1 is the alloc list */
366 int tdb_spinlock(TDB_CONTEXT
*tdb
, int list
, int rw_type
)
368 tdb_rwlock_t
*rwlocks
;
370 if (!tdb
->map_ptr
) return -1;
371 rwlocks
= (tdb_rwlock_t
*)((char *)tdb
->map_ptr
+ tdb
->header
.rwlocks
);
375 __read_lock(&rwlocks
[list
+1]);
379 __write_lock(&rwlocks
[list
+1]);
383 return TDB_ERRCODE(TDB_ERR_LOCK
, -1);
388 /* unlock the database. */
389 int tdb_spinunlock(TDB_CONTEXT
*tdb
, int list
, int rw_type
)
391 tdb_rwlock_t
*rwlocks
;
393 if (!tdb
->map_ptr
) return -1;
394 rwlocks
= (tdb_rwlock_t
*)((char *)tdb
->map_ptr
+ tdb
->header
.rwlocks
);
398 __read_unlock(&rwlocks
[list
+1]);
402 __write_unlock(&rwlocks
[list
+1]);
406 return TDB_ERRCODE(TDB_ERR_LOCK
, -1);
412 int tdb_create_rwlocks(int fd
, unsigned int hash_size
)
415 tdb_rwlock_t
*rwlocks
;
417 size
= TDB_SPINLOCK_SIZE(hash_size
);
418 rwlocks
= malloc(size
);
422 for(i
= 0; i
< hash_size
+1; i
++) {
423 __spin_lock_init(&rwlocks
[i
].lock
);
424 rwlocks
[i
].count
= 0;
427 /* Write it out (appending to end) */
428 if (write(fd
, rwlocks
, size
) != size
) {
432 smp_machine
= this_is_smp();
437 int tdb_clear_spinlocks(TDB_CONTEXT
*tdb
)
439 tdb_rwlock_t
*rwlocks
;
442 if (tdb
->header
.rwlocks
== 0) return 0;
443 if (!tdb
->map_ptr
) return -1;
445 /* We're mmapped here */
446 rwlocks
= (tdb_rwlock_t
*)((char *)tdb
->map_ptr
+ tdb
->header
.rwlocks
);
447 for(i
= 0; i
< tdb
->header
.hash_size
+1; i
++) {
448 __spin_lock_init(&rwlocks
[i
].lock
);
449 rwlocks
[i
].count
= 0;
454 int tdb_create_rwlocks(int fd
, unsigned int hash_size
) { return 0; }
455 int tdb_spinlock(TDB_CONTEXT
*tdb
, int list
, int rw_type
) { return -1; }
456 int tdb_spinunlock(TDB_CONTEXT
*tdb
, int list
, int rw_type
) { return -1; }
458 /* Non-spinlock version: remove spinlock pointer */
459 int tdb_clear_spinlocks(TDB_CONTEXT
*tdb
)
461 tdb_off off
= (tdb_off
)((char *)&tdb
->header
.rwlocks
462 - (char *)&tdb
->header
);
464 tdb
->header
.rwlocks
= 0;
465 if (lseek(tdb
->fd
, off
, SEEK_SET
) != off
466 || write(tdb
->fd
, (void *)&tdb
->header
.rwlocks
,
467 sizeof(tdb
->header
.rwlocks
))
468 != sizeof(tdb
->header
.rwlocks
))