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 int w1_register_family(struct w1_family *newf) 33 { 34 struct list_head *ent, *n; 35 struct w1_family *f; 36 int ret = 0; 37 38 spin_lock(&w1_flock); 39 list_for_each_safe(ent, n, &w1_families) { 40 f = list_entry(ent, struct w1_family, family_entry); 41 42 if (f->fid == newf->fid) { 43 ret = -EEXIST; 44 break; 45 } 46 } 47 48 if (!ret) { 49 atomic_set(&newf->refcnt, 0); 50 newf->need_exit = 0; 51 list_add_tail(&newf->family_entry, &w1_families); 52 } 53 spin_unlock(&w1_flock); 54 55 w1_reconnect_slaves(newf); 56 57 return ret; 58 } 59 60 void w1_unregister_family(struct w1_family *fent) 61 { 62 struct list_head *ent, *n; 63 struct w1_family *f; 64 65 spin_lock(&w1_flock); 66 list_for_each_safe(ent, n, &w1_families) { 67 f = list_entry(ent, struct w1_family, family_entry); 68 69 if (f->fid == fent->fid) { 70 list_del(&fent->family_entry); 71 break; 72 } 73 } 74 75 fent->need_exit = 1; 76 77 spin_unlock(&w1_flock); 78 79 while (atomic_read(&fent->refcnt)) { 80 printk(KERN_INFO "Waiting for family %u to become free: refcnt=%d.\n", 81 fent->fid, atomic_read(&fent->refcnt)); 82 83 if (msleep_interruptible(1000)) 84 flush_signals(current); 85 } 86 } 87 88 /* 89 * Should be called under w1_flock held. 90 */ 91 struct w1_family * w1_family_registered(u8 fid) 92 { 93 struct list_head *ent, *n; 94 struct w1_family *f = NULL; 95 int ret = 0; 96 97 list_for_each_safe(ent, n, &w1_families) { 98 f = list_entry(ent, struct w1_family, family_entry); 99 100 if (f->fid == fid) { 101 ret = 1; 102 break; 103 } 104 } 105 106 return (ret) ? f : NULL; 107 } 108 109 void w1_family_put(struct w1_family *f) 110 { 111 spin_lock(&w1_flock); 112 __w1_family_put(f); 113 spin_unlock(&w1_flock); 114 } 115 116 void __w1_family_put(struct w1_family *f) 117 { 118 if (atomic_dec_and_test(&f->refcnt)) 119 f->need_exit = 1; 120 } 121 122 void w1_family_get(struct w1_family *f) 123 { 124 spin_lock(&w1_flock); 125 __w1_family_get(f); 126 spin_unlock(&w1_flock); 127 128 } 129 130 void __w1_family_get(struct w1_family *f) 131 { 132 smp_mb__before_atomic_inc(); 133 atomic_inc(&f->refcnt); 134 smp_mb__after_atomic_inc(); 135 } 136 137 EXPORT_SYMBOL(w1_family_get); 138 EXPORT_SYMBOL(w1_family_put); 139 EXPORT_SYMBOL(w1_family_registered); 140 EXPORT_SYMBOL(w1_unregister_family); 141 EXPORT_SYMBOL(w1_register_family); 142