/*
Unix SMB/CIFS implementation.
trivial database library
Copyright (C) Anton Blanchard 2001
** NOTE! The following LGPL license applies to the tdb
** library. This does NOT imply that all of Samba is released
** under the LGPL
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#if HAVE_CONFIG_H
#include <config.h>
#endif
#ifdef STANDALONE
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/stat.h>
#include <time.h>
#include <signal.h>
#include "tdb.h"
#include "spinlock.h"
#define DEBUG
#else
#include "includes.h"
#endif
#ifdef USE_SPINLOCKS
/*
* ARCH SPECIFIC
*/
#if defined(SPARC_SPINLOCKS)
static inline int __spin_trylock(spinlock_t *lock)
{
unsigned int result;
asm volatile("ldstub [%1], %0"
: "=r" (result)
: "r" (lock)
: "memory");
return (result == 0) ? 0 : EBUSY;
}
static inline void __spin_unlock(spinlock_t *lock)
{
asm volatile("":::"memory");
*lock = 0;
}
static inline void __spin_lock_init(spinlock_t *lock)
{
*lock = 0;
}
static inline int __spin_is_locked(spinlock_t *lock)
{
return (*lock != 0);
}
#elif defined(POWERPC_SPINLOCKS)
static inline int __spin_trylock(spinlock_t *lock)
{
unsigned int result;
__asm__ __volatile__(
"1: lwarx %0,0,%1\n\
cmpwi 0,%0,0\n\
li %0,0\n\
bne- 2f\n\
li %0,1\n\
stwcx. %0,0,%1\n\
bne- 1b\n\
isync\n\
2:" : "=&r"(result)
: "r"(lock)
: "cr0", "memory");
return (result == 1) ? 0 : EBUSY;
}
static inline void __spin_unlock(spinlock_t *lock)
{
asm volatile("eieio":::"memory");
*lock = 0;
}
static inline void __spin_lock_init(spinlock_t *lock)
{
*lock = 0;
}
static inline int __spin_is_locked(spinlock_t *lock)
{
return (*lock != 0);
}
#elif defined(INTEL_SPINLOCKS)
static inline int __spin_trylock(spinlock_t *lock)
{
int oldval;
asm volatile("xchgl %0,%1"
: "=r" (oldval), "=m" (*lock)
: "0" (0)
: "memory");
return oldval > 0 ? 0 : EBUSY;
}
static inline void __spin_unlock(spinlock_t *lock)
{
asm volatile("":::"memory");
*lock = 1;
}
static inline void __spin_lock_init(spinlock_t *lock)
{
*lock = 1;
}
static inline int __spin_is_locked(spinlock_t *lock)
{
return (*lock != 1);
}
#elif defined(MIPS_SPINLOCKS) && defined(sgi) && (_COMPILER_VERSION >= 730)
/* Implement spinlocks on IRIX using the MIPSPro atomic fetch operations. See
* sync(3) for the details of the intrinsic operations.
*
* "sgi" and "_COMPILER_VERSION" are always defined by MIPSPro.
*/
#ifdef STANDALONE
/* MIPSPro 7.3 has "__inline" as an extension, but not "inline. */
#define inline __inline
#endif /* STANDALONE */
/* Returns 0 if the lock is acquired, EBUSY otherwise. */
static inline int __spin_trylock(spinlock_t *lock)
{
unsigned int val;
val = __lock_test_and_set(lock, 1);
return val == 0 ? 0 : EBUSY;
}
static inline void __spin_unlock(spinlock_t *lock)
{
__lock_release(lock);
}
static inline void __spin_lock_init(spinlock_t *lock)
{
__lock_release(lock);
}
/* Returns 1 if the lock is held, 0 otherwise. */
static inline int __spin_is_locked(spinlock_t *lock)
{
unsigned int val;
val = __add_and_fetch(lock, 0);
return val;
}
#elif defined(MIPS_SPINLOCKS)
static inline unsigned int load_linked(unsigned long addr)
{
unsigned int res;
__asm__ __volatile__("ll\t%0,(%1)"
: "=r" (res)
: "r" (addr));
return res;
}
static inline unsigned int store_conditional(unsigned long addr, unsigned int value)
{
unsigned int res;
__asm__ __volatile__("sc\t%0,(%2)"
: "=r" (res)
: "0" (value), "r" (addr));
return res;
}
static inline int __spin_trylock(spinlock_t *lock)
{
unsigned int mw;
do {
mw = load_linked(lock);
if (mw)
return EBUSY;
} while (!store_conditional(lock, 1));
asm volatile("":::"memory");
return 0;
}
static inline void __spin_unlock(spinlock_t *lock)
{
asm volatile("":::"memory");
*lock = 0;
}
static inline void __spin_lock_init(spinlock_t *lock)
{
*lock = 0;
}
static inline int __spin_is_locked(spinlock_t *lock)
{
return (*lock != 0);
}
#else
#error Need to implement spinlock code in spinlock.c
#endif
/*
* OS SPECIFIC
*/
static void yield_cpu(void)
{
struct timespec tm;
#ifdef USE_SCHED_YIELD
sched_yield();
#else
/* Linux will busy loop for delays < 2ms on real time tasks */
tm.tv_sec = 0;
tm.tv_nsec = 2000000L + 1;
nanosleep(&tm, NULL);
#endif
}
static int this_is_smp(void)
{
#if defined(HAVE_SYSCONF) && defined(SYSCONF_SC_NPROC_ONLN)
return (sysconf(_SC_NPROC_ONLN) > 1) ? 1 : 0;
#else
return 0;
#endif
}
/*
* GENERIC
*/
static int smp_machine = 0;
static inline void __spin_lock(spinlock_t *lock)
{
int ntries = 0;
while(__spin_trylock(lock)) {
while(__spin_is_locked(lock)) {
if (smp_machine && ntries++ < MAX_BUSY_LOOPS)
continue;
yield_cpu();
}
}
}
static void __read_lock(tdb_rwlock_t *rwlock)
{
int ntries = 0;
while(1) {
__spin_lock(&rwlock->lock);
if (!(rwlock->count & RWLOCK_BIAS)) {
rwlock->count++;
__spin_unlock(&rwlock->lock);
return;
}
__spin_unlock(&rwlock->lock);
while(rwlock->count & RWLOCK_BIAS) {
if (smp_machine && ntries++ < MAX_BUSY_LOOPS)
continue;
yield_cpu();
}
}
}
static void __write_lock(tdb_rwlock_t *rwlock)
{
int ntries = 0;
while(1) {
__spin_lock(&rwlock->lock);
if (rwlock->count == 0) {
rwlock->count |= RWLOCK_BIAS;
__spin_unlock(&rwlock->lock);
return;
}
__spin_unlock(&rwlock->lock);
while(rwlock->count != 0) {
if (smp_machine && ntries++ < MAX_BUSY_LOOPS)
continue;
yield_cpu();
}
}
}
static void __write_unlock(tdb_rwlock_t *rwlock)
{
__spin_lock(&rwlock->lock);
#ifdef DEBUG
if (!(rwlock->count & RWLOCK_BIAS))
fprintf(stderr, "bug: write_unlock\n");
#endif
rwlock->count &= ~RWLOCK_BIAS;
__spin_unlock(&rwlock->lock);
}
static void __read_unlock(tdb_rwlock_t *rwlock)
{
__spin_lock(&rwlock->lock);
#ifdef DEBUG
if (!rwlock->count)
fprintf(stderr, "bug: read_unlock\n");
if (rwlock->count & RWLOCK_BIAS)
fprintf(stderr, "bug: read_unlock\n");
#endif
rwlock->count--;
__spin_unlock(&rwlock->lock);
}
/* TDB SPECIFIC */
/* lock a list in the database. list -1 is the alloc list */
int tdb_spinlock(TDB_CONTEXT *tdb, int list, int rw_type)
{
tdb_rwlock_t *rwlocks;
if (!tdb->map_ptr) return -1;
rwlocks = (tdb_rwlock_t *)((char *)tdb->map_ptr + tdb->header.rwlocks);
switch(rw_type) {
case F_RDLCK:
__read_lock(&rwlocks[list+1]);
break;
case F_WRLCK:
__write_lock(&rwlocks[list+1]);
break;
default:
return TDB_ERRCODE(TDB_ERR_LOCK, -1);
}
return 0;
}
/* unlock the database. */
int tdb_spinunlock(TDB_CONTEXT *tdb, int list, int rw_type)
{
tdb_rwlock_t *rwlocks;
if (!tdb->map_ptr) return -1;
rwlocks = (tdb_rwlock_t *)((char *)tdb->map_ptr + tdb->header.rwlocks);
switch(rw_type) {
case F_RDLCK:
__read_unlock(&rwlocks[list+1]);
break;
case F_WRLCK:
__write_unlock(&rwlocks[list+1]);
break;
default:
return TDB_ERRCODE(TDB_ERR_LOCK, -1);
}
return 0;
}
int tdb_create_rwlocks(int fd, unsigned int hash_size)
{
unsigned size, i;
tdb_rwlock_t *rwlocks;
size = TDB_SPINLOCK_SIZE(hash_size);
rwlocks = malloc(size);
if (!rwlocks)
return -1;
for(i = 0; i < hash_size+1; i++) {
__spin_lock_init(&rwlocks[i].lock);
rwlocks[i].count = 0;
}
/* Write it out (appending to end) */
if (write(fd, rwlocks, size) != size) {
free(rwlocks);
return -1;
}
smp_machine = this_is_smp();
free(rwlocks);
return 0;
}
int tdb_clear_spinlocks(TDB_CONTEXT *tdb)
{
tdb_rwlock_t *rwlocks;
unsigned i;
if (tdb->header.rwlocks == 0) return 0;
if (!tdb->map_ptr) return -1;
/* We're mmapped here */
rwlocks = (tdb_rwlock_t *)((char *)tdb->map_ptr + tdb->header.rwlocks);
for(i = 0; i < tdb->header.hash_size+1; i++) {
__spin_lock_init(&rwlocks[i].lock);
rwlocks[i].count = 0;
}
return 0;
}
#else
int tdb_create_rwlocks(int fd, unsigned int hash_size) { return 0; }
int tdb_spinlock(TDB_CONTEXT *tdb, int list, int rw_type) { return -1; }
int tdb_spinunlock(TDB_CONTEXT *tdb, int list, int rw_type) { return -1; }
/* Non-spinlock version: remove spinlock pointer */
int tdb_clear_spinlocks(TDB_CONTEXT *tdb)
{
tdb_off off = (tdb_off)((char *)&tdb->header.rwlocks
- (char *)&tdb->header);
tdb->header.rwlocks = 0;
if (lseek(tdb->fd, off, SEEK_SET) != off
|| write(tdb->fd, (void *)&tdb->header.rwlocks,
sizeof(tdb->header.rwlocks))
!= sizeof(tdb->header.rwlocks))
return -1;
return 0;
}
#endif