drivers/connector/cn_queue.c

   1 /*
   2  *      cn_queue.c
   3  *
   4  * 2004+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
   5  * All rights reserved.
   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
  23 #include <linux/kernel.h>
  24 #include <linux/module.h>
  25 #include <linux/list.h>
  26 #include <linux/workqueue.h>
  27 #include <linux/spinlock.h>
  28 #include <linux/slab.h>
  29 #include <linux/skbuff.h>
  30 #include <linux/suspend.h>
  31 #include <linux/connector.h>
  32 #include <linux/delay.h>
  33
  34 static struct cn_callback_entry *
  35 cn_queue_alloc_callback_entry(struct cn_queue_dev *dev, const char *name,
  36                               struct cb_id *id,
  37                               void (*callback)(struct cn_msg *, struct netlink_skb_parms *))
  38 {
  39         struct cn_callback_entry *cbq;
  40
  41         cbq = kzalloc(sizeof(*cbq), GFP_KERNEL);
  42         if (!cbq) {
  43                 printk(KERN_ERR "Failed to create new callback queue.\n");
  44                 return NULL;
  45         }
  46
  47         atomic_set(&cbq->refcnt, 1);
  48
  49         atomic_inc(&dev->refcnt);
  50         cbq->pdev = dev;
  51
  52         snprintf(cbq->id.name, sizeof(cbq->id.name), "%s", name);
  53         memcpy(&cbq->id.id, id, sizeof(struct cb_id));
  54         cbq->callback = callback;
  55         return cbq;
  56 }
  57
  58 void cn_queue_release_callback(struct cn_callback_entry *cbq)
  59 {
  60         if (!atomic_dec_and_test(&cbq->refcnt))
  61                 return;
  62
  63         atomic_dec(&cbq->pdev->refcnt);
  64         kfree(cbq);
  65 }
  66
  67 int cn_cb_equal(struct cb_id *i1, struct cb_id *i2)
  68 {
  69         return ((i1->idx == i2->idx) && (i1->val == i2->val));
  70 }
  71
  72 int cn_queue_add_callback(struct cn_queue_dev *dev, const char *name,
  73                           struct cb_id *id,
  74                           void (*callback)(struct cn_msg *, struct netlink_skb_parms *))
  75 {
  76         struct cn_callback_entry *cbq, *__cbq;
  77         int found = 0;
  78
  79         cbq = cn_queue_alloc_callback_entry(dev, name, id, callback);
  80         if (!cbq)
  81                 return -ENOMEM;
  82
  83         spin_lock_bh(&dev->queue_lock);
  84         list_for_each_entry(__cbq, &dev->queue_list, callback_entry) {
  85                 if (cn_cb_equal(&__cbq->id.id, id)) {
  86                         found = 1;
  87                         break;
  88                 }
  89         }
  90         if (!found)
  91                 list_add_tail(&cbq->callback_entry, &dev->queue_list);
  92         spin_unlock_bh(&dev->queue_lock);
  93
  94         if (found) {
  95                 cn_queue_release_callback(cbq);
  96                 return -EINVAL;
  97         }
  98
  99         cbq->seq = 0;
 100         cbq->group = cbq->id.id.idx;
 101
 102         return 0;
 103 }
 104
 105 void cn_queue_del_callback(struct cn_queue_dev *dev, struct cb_id *id)
 106 {
 107         struct cn_callback_entry *cbq, *n;
 108         int found = 0;
 109
 110         spin_lock_bh(&dev->queue_lock);
 111         list_for_each_entry_safe(cbq, n, &dev->queue_list, callback_entry) {
 112                 if (cn_cb_equal(&cbq->id.id, id)) {
 113                         list_del(&cbq->callback_entry);
 114                         found = 1;
 115                         break;
 116                 }
 117         }
 118         spin_unlock_bh(&dev->queue_lock);
 119
 120         if (found)
 121                 cn_queue_release_callback(cbq);
 122 }
 123
 124 struct cn_queue_dev *cn_queue_alloc_dev(const char *name, struct sock *nls)
 125 {
 126         struct cn_queue_dev *dev;
 127
 128         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 129         if (!dev)
 130                 return NULL;
 131
 132         snprintf(dev->name, sizeof(dev->name), "%s", name);
 133         atomic_set(&dev->refcnt, 0);
 134         INIT_LIST_HEAD(&dev->queue_list);
 135         spin_lock_init(&dev->queue_lock);
 136
 137         dev->nls = nls;
 138
 139         return dev;
 140 }
 141
 142 void cn_queue_free_dev(struct cn_queue_dev *dev)
 143 {
 144         struct cn_callback_entry *cbq, *n;
 145
 146         spin_lock_bh(&dev->queue_lock);
 147         list_for_each_entry_safe(cbq, n, &dev->queue_list, callback_entry)
 148                 list_del(&cbq->callback_entry);
 149         spin_unlock_bh(&dev->queue_lock);
 150
 151         while (atomic_read(&dev->refcnt)) {
 152                 printk(KERN_INFO "Waiting for %s to become free: refcnt=%d.\n",
 153                        dev->name, atomic_read(&dev->refcnt));
 154                 msleep(1000);
 155         }
 156
 157         kfree(dev);
 158         dev = NULL;
 159 }