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 *,
  38                                                struct netlink_skb_parms *))
  39 {
  40         struct cn_callback_entry *cbq;
  41
  42         cbq = kzalloc(sizeof(*cbq), GFP_KERNEL);
  43         if (!cbq) {
  44                 pr_err("Failed to create new callback queue.\n");
  45                 return NULL;
  46         }
  47
  48         refcount_set(&cbq->refcnt, 1);
  49
  50         atomic_inc(&dev->refcnt);
  51         cbq->pdev = dev;
  52
  53         snprintf(cbq->id.name, sizeof(cbq->id.name), "%s", name);
  54         memcpy(&cbq->id.id, id, sizeof(struct cb_id));
  55         cbq->callback = callback;
  56         return cbq;
  57 }
  58
  59 void cn_queue_release_callback(struct cn_callback_entry *cbq)
  60 {
  61         if (!refcount_dec_and_test(&cbq->refcnt))
  62                 return;
  63
  64         atomic_dec(&cbq->pdev->refcnt);
  65         kfree(cbq);
  66 }
  67
  68 int cn_cb_equal(struct cb_id *i1, struct cb_id *i2)
  69 {
  70         return ((i1->idx == i2->idx) && (i1->val == i2->val));
  71 }
  72
  73 int cn_queue_add_callback(struct cn_queue_dev *dev, const char *name,
  74                           struct cb_id *id,
  75                           void (*callback)(struct cn_msg *,
  76                                            struct netlink_skb_parms *))
  77 {
  78         struct cn_callback_entry *cbq, *__cbq;
  79         int found = 0;
  80
  81         cbq = cn_queue_alloc_callback_entry(dev, name, id, callback);
  82         if (!cbq)
  83                 return -ENOMEM;
  84
  85         spin_lock_bh(&dev->queue_lock);
  86         list_for_each_entry(__cbq, &dev->queue_list, callback_entry) {
  87                 if (cn_cb_equal(&__cbq->id.id, id)) {
  88                         found = 1;
  89                         break;
  90                 }
  91         }
  92         if (!found)
  93                 list_add_tail(&cbq->callback_entry, &dev->queue_list);
  94         spin_unlock_bh(&dev->queue_lock);
  95
  96         if (found) {
  97                 cn_queue_release_callback(cbq);
  98                 return -EINVAL;
  99         }
 100
 101         cbq->seq = 0;
 102         cbq->group = cbq->id.id.idx;
 103
 104         return 0;
 105 }
 106
 107 void cn_queue_del_callback(struct cn_queue_dev *dev, struct cb_id *id)
 108 {
 109         struct cn_callback_entry *cbq, *n;
 110         int found = 0;
 111
 112         spin_lock_bh(&dev->queue_lock);
 113         list_for_each_entry_safe(cbq, n, &dev->queue_list, callback_entry) {
 114                 if (cn_cb_equal(&cbq->id.id, id)) {
 115                         list_del(&cbq->callback_entry);
 116                         found = 1;
 117                         break;
 118                 }
 119         }
 120         spin_unlock_bh(&dev->queue_lock);
 121
 122         if (found)
 123                 cn_queue_release_callback(cbq);
 124 }
 125
 126 struct cn_queue_dev *cn_queue_alloc_dev(const char *name, struct sock *nls)
 127 {
 128         struct cn_queue_dev *dev;
 129
 130         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 131         if (!dev)
 132                 return NULL;
 133
 134         snprintf(dev->name, sizeof(dev->name), "%s", name);
 135         atomic_set(&dev->refcnt, 0);
 136         INIT_LIST_HEAD(&dev->queue_list);
 137         spin_lock_init(&dev->queue_lock);
 138
 139         dev->nls = nls;
 140
 141         return dev;
 142 }
 143
 144 void cn_queue_free_dev(struct cn_queue_dev *dev)
 145 {
 146         struct cn_callback_entry *cbq, *n;
 147
 148         spin_lock_bh(&dev->queue_lock);
 149         list_for_each_entry_safe(cbq, n, &dev->queue_list, callback_entry)
 150                 list_del(&cbq->callback_entry);
 151         spin_unlock_bh(&dev->queue_lock);
 152
 153         while (atomic_read(&dev->refcnt)) {
 154                 pr_info("Waiting for %s to become free: refcnt=%d.\n",
 155                        dev->name, atomic_read(&dev->refcnt));
 156                 msleep(1000);
 157         }
 158
 159         kfree(dev);
 160         dev = NULL;
 161 }