151 lines
3.1 KiB
C
151 lines
3.1 KiB
C
/*
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* w1_family.c
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*
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* Copyright (c) 2004 Evgeniy Polyakov <johnpol@2ka.mipt.ru>
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*
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <linux/spinlock.h>
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#include <linux/list.h>
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#include <linux/delay.h>
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#include "w1_family.h"
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DEFINE_SPINLOCK(w1_flock);
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static LIST_HEAD(w1_families);
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static int w1_check_family(struct w1_family *f)
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{
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if (!f->fops->rname || !f->fops->rbin || !f->fops->rval || !f->fops->rvalname)
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return -EINVAL;
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return 0;
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}
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int w1_register_family(struct w1_family *newf)
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{
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struct list_head *ent, *n;
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struct w1_family *f;
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int ret = 0;
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if (w1_check_family(newf))
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return -EINVAL;
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spin_lock(&w1_flock);
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list_for_each_safe(ent, n, &w1_families) {
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f = list_entry(ent, struct w1_family, family_entry);
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if (f->fid == newf->fid) {
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ret = -EEXIST;
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break;
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}
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}
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if (!ret) {
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atomic_set(&newf->refcnt, 0);
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newf->need_exit = 0;
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list_add_tail(&newf->family_entry, &w1_families);
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}
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spin_unlock(&w1_flock);
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return ret;
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}
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void w1_unregister_family(struct w1_family *fent)
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{
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struct list_head *ent, *n;
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struct w1_family *f;
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spin_lock(&w1_flock);
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list_for_each_safe(ent, n, &w1_families) {
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f = list_entry(ent, struct w1_family, family_entry);
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if (f->fid == fent->fid) {
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list_del(&fent->family_entry);
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break;
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}
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}
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fent->need_exit = 1;
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spin_unlock(&w1_flock);
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while (atomic_read(&fent->refcnt)) {
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printk(KERN_INFO "Waiting for family %u to become free: refcnt=%d.\n",
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fent->fid, atomic_read(&fent->refcnt));
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if (msleep_interruptible(1000))
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flush_signals(current);
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}
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}
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/*
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* Should be called under w1_flock held.
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*/
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struct w1_family * w1_family_registered(u8 fid)
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{
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struct list_head *ent, *n;
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struct w1_family *f = NULL;
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int ret = 0;
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list_for_each_safe(ent, n, &w1_families) {
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f = list_entry(ent, struct w1_family, family_entry);
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if (f->fid == fid) {
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ret = 1;
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break;
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}
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}
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return (ret) ? f : NULL;
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}
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void w1_family_put(struct w1_family *f)
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{
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spin_lock(&w1_flock);
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__w1_family_put(f);
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spin_unlock(&w1_flock);
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}
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void __w1_family_put(struct w1_family *f)
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{
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if (atomic_dec_and_test(&f->refcnt))
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f->need_exit = 1;
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}
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void w1_family_get(struct w1_family *f)
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{
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spin_lock(&w1_flock);
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__w1_family_get(f);
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spin_unlock(&w1_flock);
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}
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void __w1_family_get(struct w1_family *f)
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{
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smp_mb__before_atomic_inc();
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atomic_inc(&f->refcnt);
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smp_mb__after_atomic_inc();
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}
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EXPORT_SYMBOL(w1_family_get);
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EXPORT_SYMBOL(w1_family_put);
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EXPORT_SYMBOL(w1_family_registered);
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EXPORT_SYMBOL(w1_unregister_family);
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EXPORT_SYMBOL(w1_register_family);
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