w1_family.c
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/*
* w1_family.c
*
* Copyright (c) 2004 Evgeniy Polyakov <johnpol@2ka.mipt.ru>
*
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/spinlock.h>
#include <linux/list.h>
#include <linux/sched.h> /* schedule_timeout() */
#include <linux/delay.h>
#include "w1_family.h"
#include "w1.h"
DEFINE_SPINLOCK(w1_flock);
static LIST_HEAD(w1_families);
int w1_register_family(struct w1_family *newf)
{
struct list_head *ent, *n;
struct w1_family *f;
int ret = 0;
spin_lock(&w1_flock);
list_for_each_safe(ent, n, &w1_families) {
f = list_entry(ent, struct w1_family, family_entry);
if (f->fid == newf->fid) {
ret = -EEXIST;
break;
}
}
if (!ret) {
atomic_set(&newf->refcnt, 0);
newf->need_exit = 0;
list_add_tail(&newf->family_entry, &w1_families);
}
spin_unlock(&w1_flock);
w1_reconnect_slaves(newf);
return ret;
}
void w1_unregister_family(struct w1_family *fent)
{
struct list_head *ent, *n;
struct w1_family *f;
spin_lock(&w1_flock);
list_for_each_safe(ent, n, &w1_families) {
f = list_entry(ent, struct w1_family, family_entry);
if (f->fid == fent->fid) {
list_del(&fent->family_entry);
break;
}
}
fent->need_exit = 1;
spin_unlock(&w1_flock);
while (atomic_read(&fent->refcnt)) {
printk(KERN_INFO "Waiting for family %u to become free: refcnt=%d.\n",
fent->fid, atomic_read(&fent->refcnt));
if (msleep_interruptible(1000))
flush_signals(current);
}
}
/*
* Should be called under w1_flock held.
*/
struct w1_family * w1_family_registered(u8 fid)
{
struct list_head *ent, *n;
struct w1_family *f = NULL;
int ret = 0;
list_for_each_safe(ent, n, &w1_families) {
f = list_entry(ent, struct w1_family, family_entry);
if (f->fid == fid) {
ret = 1;
break;
}
}
return (ret) ? f : NULL;
}
static void __w1_family_put(struct w1_family *f)
{
if (atomic_dec_and_test(&f->refcnt))
f->need_exit = 1;
}
void w1_family_put(struct w1_family *f)
{
spin_lock(&w1_flock);
__w1_family_put(f);
spin_unlock(&w1_flock);
}
#if 0
void w1_family_get(struct w1_family *f)
{
spin_lock(&w1_flock);
__w1_family_get(f);
spin_unlock(&w1_flock);
}
#endif /* 0 */
void __w1_family_get(struct w1_family *f)
{
smp_mb__before_atomic_inc();
atomic_inc(&f->refcnt);
smp_mb__after_atomic_inc();
}
EXPORT_SYMBOL(w1_unregister_family);
EXPORT_SYMBOL(w1_register_family);