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); 153