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   1 /*
   2  *      w1_family.c
   3  *
   4  * Copyright (c) 2004 Evgeniy Polyakov <johnpol@2ka.mipt.ru>
   5  *
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  20  */
  21
  22 #include <linux/spinlock.h>
  23 #include <linux/list.h>
  24 #include <linux/delay.h>
  25
  26 #include "w1_family.h"
  27
  28 DEFINE_SPINLOCK(w1_flock);
  29 static LIST_HEAD(w1_families);
  30 extern void w1_reconnect_slaves(struct w1_family *f);
  31
  32 static int w1_check_family(struct w1_family *f)
  33 {
  34         if (!f->fops->rname || !f->fops->rbin)
  35                 return -EINVAL;
  36
  37         return 0;
  38 }
  39
  40 int w1_register_family(struct w1_family *newf)
  41 {
  42         struct list_head *ent, *n;
  43         struct w1_family *f;
  44         int ret = 0;
  45
  46         if (w1_check_family(newf))
  47                 return -EINVAL;
  48
  49         spin_lock(&w1_flock);
  50         list_for_each_safe(ent, n, &w1_families) {
  51                 f = list_entry(ent, struct w1_family, family_entry);
  52
  53                 if (f->fid == newf->fid) {
  54                         ret = -EEXIST;
  55                         break;
  56                 }
  57         }
  58
  59         if (!ret) {
  60                 atomic_set(&newf->refcnt, 0);
  61                 newf->need_exit = 0;
  62                 list_add_tail(&newf->family_entry, &w1_families);
  63         }
  64         spin_unlock(&w1_flock);
  65
  66         w1_reconnect_slaves(newf);
  67
  68         return ret;
  69 }
  70
  71 void w1_unregister_family(struct w1_family *fent)
  72 {
  73         struct list_head *ent, *n;
  74         struct w1_family *f;
  75
  76         spin_lock(&w1_flock);
  77         list_for_each_safe(ent, n, &w1_families) {
  78                 f = list_entry(ent, struct w1_family, family_entry);
  79
  80                 if (f->fid == fent->fid) {
  81                         list_del(&fent->family_entry);
  82                         break;
  83                 }
  84         }
  85
  86         fent->need_exit = 1;
  87
  88         spin_unlock(&w1_flock);
  89
  90         while (atomic_read(&fent->refcnt)) {
  91                 printk(KERN_INFO "Waiting for family %u to become free: refcnt=%d.\n",
  92                                 fent->fid, atomic_read(&fent->refcnt));
  93
  94                 if (msleep_interruptible(1000))
  95                         flush_signals(current);
  96         }
  97 }
  98
  99 /*
 100  * Should be called under w1_flock held.
 101  */
 102 struct w1_family * w1_family_registered(u8 fid)
 103 {
 104         struct list_head *ent, *n;
 105         struct w1_family *f = NULL;
 106         int ret = 0;
 107
 108         list_for_each_safe(ent, n, &w1_families) {
 109                 f = list_entry(ent, struct w1_family, family_entry);
 110
 111                 if (f->fid == fid) {
 112                         ret = 1;
 113                         break;
 114                 }
 115         }
 116
 117         return (ret) ? f : NULL;
 118 }
 119
 120 void w1_family_put(struct w1_family *f)
 121 {
 122         spin_lock(&w1_flock);
 123         __w1_family_put(f);
 124         spin_unlock(&w1_flock);
 125 }
 126
 127 void __w1_family_put(struct w1_family *f)
 128 {
 129         if (atomic_dec_and_test(&f->refcnt))
 130                 f->need_exit = 1;
 131 }
 132
 133 void w1_family_get(struct w1_family *f)
 134 {
 135         spin_lock(&w1_flock);
 136         __w1_family_get(f);
 137         spin_unlock(&w1_flock);
 138
 139 }
 140
 141 void __w1_family_get(struct w1_family *f)
 142 {
 143         smp_mb__before_atomic_inc();
 144         atomic_inc(&f->refcnt);
 145         smp_mb__after_atomic_inc();
 146 }
 147
 148 EXPORT_SYMBOL(w1_family_get);
 149 EXPORT_SYMBOL(w1_family_put);
 150 EXPORT_SYMBOL(w1_family_registered);
 151 EXPORT_SYMBOL(w1_unregister_family);
 152 EXPORT_SYMBOL(w1_register_family);