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/sched.h> /* schedule_timeout() */ 25 #include <linux/delay.h> 26 27 #include "w1_family.h" 28 #include "w1.h" 29 30 DEFINE_SPINLOCK(w1_flock); 31 static LIST_HEAD(w1_families); 32 33 int w1_register_family(struct w1_family *newf) 34 { 35 struct list_head *ent, *n; 36 struct w1_family *f; 37 int ret = 0; 38 39 spin_lock(&w1_flock); 40 list_for_each_safe(ent, n, &w1_families) { 41 f = list_entry(ent, struct w1_family, family_entry); 42 43 if (f->fid == newf->fid) { 44 ret = -EEXIST; 45 break; 46 } 47 } 48 49 if (!ret) { 50 atomic_set(&newf->refcnt, 0); 51 newf->need_exit = 0; 52 list_add_tail(&newf->family_entry, &w1_families); 53 } 54 spin_unlock(&w1_flock); 55 56 w1_reconnect_slaves(newf); 57 58 return ret; 59 } 60 61 void w1_unregister_family(struct w1_family *fent) 62 { 63 struct list_head *ent, *n; 64 struct w1_family *f; 65 66 spin_lock(&w1_flock); 67 list_for_each_safe(ent, n, &w1_families) { 68 f = list_entry(ent, struct w1_family, family_entry); 69 70 if (f->fid == fent->fid) { 71 list_del(&fent->family_entry); 72 break; 73 } 74 } 75 76 fent->need_exit = 1; 77 78 spin_unlock(&w1_flock); 79 80 while (atomic_read(&fent->refcnt)) { 81 printk(KERN_INFO "Waiting for family %u to become free: refcnt=%d.\n", 82 fent->fid, atomic_read(&fent->refcnt)); 83 84 if (msleep_interruptible(1000)) 85 flush_signals(current); 86 } 87 } 88 89 /* 90 * Should be called under w1_flock held. 91 */ 92 struct w1_family * w1_family_registered(u8 fid) 93 { 94 struct list_head *ent, *n; 95 struct w1_family *f = NULL; 96 int ret = 0; 97 98 list_for_each_safe(ent, n, &w1_families) { 99 f = list_entry(ent, struct w1_family, family_entry); 100 101 if (f->fid == fid) { 102 ret = 1; 103 break; 104 } 105 } 106 107 return (ret) ? f : NULL; 108 } 109 110 static void __w1_family_put(struct w1_family *f) 111 { 112 if (atomic_dec_and_test(&f->refcnt)) 113 f->need_exit = 1; 114 } 115 116 void w1_family_put(struct w1_family *f) 117 { 118 spin_lock(&w1_flock); 119 __w1_family_put(f); 120 spin_unlock(&w1_flock); 121 } 122 123 #if 0 124 void w1_family_get(struct w1_family *f) 125 { 126 spin_lock(&w1_flock); 127 __w1_family_get(f); 128 spin_unlock(&w1_flock); 129 } 130 #endif /* 0 */ 131 132 void __w1_family_get(struct w1_family *f) 133 { 134 smp_mb__before_atomic_inc(); 135 atomic_inc(&f->refcnt); 136 smp_mb__after_atomic_inc(); 137 } 138 139 EXPORT_SYMBOL(w1_unregister_family); 140 EXPORT_SYMBOL(w1_register_family); 141