From: Paul Mackerras <paulus@samba.org>
Date: Sat, 13 Nov 2004 12:34:20 +0000 (+0000)
Subject: Add these files, used with TDB.
X-Git-Tag: ppp-2.4.7~173
X-Git-Url: http://git.ozlabs.org/?p=ppp.git;a=commitdiff_plain;h=4b9bf9ae2701487191810e564aaa4672eb95130e

Add these files, used with TDB.
---

diff --git a/pppd/spinlock.c b/pppd/spinlock.c
new file mode 100644
index 0000000..4df7e47
--- /dev/null
+++ b/pppd/spinlock.c
@@ -0,0 +1,473 @@
+/* 
+   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
+*/
+#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
+
+#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
diff --git a/pppd/spinlock.h b/pppd/spinlock.h
new file mode 100644
index 0000000..967fe37
--- /dev/null
+++ b/pppd/spinlock.h
@@ -0,0 +1,59 @@
+#ifndef __SPINLOCK_H__
+#define __SPINLOCK_H__
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include "tdb.h"
+
+#ifdef USE_SPINLOCKS
+
+#define RWLOCK_BIAS 0x1000UL
+
+/* OS SPECIFIC */
+#define MAX_BUSY_LOOPS 1000
+#undef USE_SCHED_YIELD
+
+/* ARCH SPECIFIC */
+/* We should make sure these are padded to a cache line */
+#if defined(SPARC_SPINLOCKS)
+typedef volatile char spinlock_t;
+#elif defined(POWERPC_SPINLOCKS)
+typedef volatile unsigned long spinlock_t;
+#elif defined(INTEL_SPINLOCKS)
+typedef volatile int spinlock_t;
+#elif defined(MIPS_SPINLOCKS)
+typedef volatile unsigned long spinlock_t;
+#else
+#error Need to implement spinlock code in spinlock.h
+#endif
+
+typedef struct {
+	spinlock_t lock;
+	volatile int count;
+} tdb_rwlock_t;
+
+int tdb_spinlock(TDB_CONTEXT *tdb, int list, int rw_type);
+int tdb_spinunlock(TDB_CONTEXT *tdb, int list, int rw_type);
+int tdb_create_rwlocks(int fd, unsigned int hash_size);
+int tdb_clear_spinlocks(TDB_CONTEXT *tdb);
+
+#define TDB_SPINLOCK_SIZE(hash_size) (((hash_size) + 1) * sizeof(tdb_rwlock_t))
+
+#else /* !USE_SPINLOCKS */
+#if 0
+#define tdb_create_rwlocks(fd, hash_size) 0
+#define tdb_spinlock(tdb, list, rw_type) (-1)
+#define tdb_spinunlock(tdb, list, rw_type) (-1)
+#else
+int tdb_spinlock(TDB_CONTEXT *tdb, int list, int rw_type);
+int tdb_spinunlock(TDB_CONTEXT *tdb, int list, int rw_type);
+int tdb_create_rwlocks(int fd, unsigned int hash_size);
+#endif
+int tdb_clear_spinlocks(TDB_CONTEXT *tdb);
+#define TDB_SPINLOCK_SIZE(hash_size) 0
+
+#endif
+
+#endif