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 35 /* 36 * This job is sent to the kevent workqueue. 37 * While no event is once sent to any callback, the connector workqueue 38 * is not created to avoid a useless waiting kernel task. 39 * Once the first event is received, we create this dedicated workqueue which 40 * is necessary because the flow of data can be high and we don't want 41 * to encumber keventd with that. 42 */ 43 static void cn_queue_create(struct work_struct *work) 44 { 45 struct cn_queue_dev *dev; 46 47 dev = container_of(work, struct cn_queue_dev, wq_creation); 48 49 dev->cn_queue = create_singlethread_workqueue(dev->name); 50 /* If we fail, we will use keventd for all following connector jobs */ 51 WARN_ON(!dev->cn_queue); 52 } 53 54 /* 55 * Queue a data sent to a callback. 56 * If the connector workqueue is already created, we queue the job on it. 57 * Otherwise, we queue the job to kevent and queue the connector workqueue 58 * creation too. 59 */ 60 int queue_cn_work(struct cn_callback_entry *cbq, struct work_struct *work) 61 { 62 struct cn_queue_dev *pdev = cbq->pdev; 63 64 if (likely(pdev->cn_queue)) 65 return queue_work(pdev->cn_queue, work); 66 67 /* Don't create the connector workqueue twice */ 68 if (atomic_inc_return(&pdev->wq_requested) == 1) 69 schedule_work(&pdev->wq_creation); 70 else 71 atomic_dec(&pdev->wq_requested); 72 73 return schedule_work(work); 74 } 75 76 void cn_queue_wrapper(struct work_struct *work) 77 { 78 struct cn_callback_entry *cbq = 79 container_of(work, struct cn_callback_entry, work); 80 struct cn_callback_data *d = &cbq->data; 81 struct cn_msg *msg = NLMSG_DATA(nlmsg_hdr(d->skb)); 82 struct netlink_skb_parms *nsp = &NETLINK_CB(d->skb); 83 84 d->callback(msg, nsp); 85 86 kfree_skb(d->skb); 87 d->skb = NULL; 88 89 kfree(d->free); 90 } 91 92 static struct cn_callback_entry * 93 cn_queue_alloc_callback_entry(char *name, struct cb_id *id, 94 void (*callback)(struct cn_msg *, struct netlink_skb_parms *)) 95 { 96 struct cn_callback_entry *cbq; 97 98 cbq = kzalloc(sizeof(*cbq), GFP_KERNEL); 99 if (!cbq) { 100 printk(KERN_ERR "Failed to create new callback queue.\n"); 101 return NULL; 102 } 103 104 snprintf(cbq->id.name, sizeof(cbq->id.name), "%s", name); 105 memcpy(&cbq->id.id, id, sizeof(struct cb_id)); 106 cbq->data.callback = callback; 107 108 INIT_WORK(&cbq->work, &cn_queue_wrapper); 109 return cbq; 110 } 111 112 static void cn_queue_free_callback(struct cn_callback_entry *cbq) 113 { 114 /* The first jobs have been sent to kevent, flush them too */ 115 flush_scheduled_work(); 116 if (cbq->pdev->cn_queue) 117 flush_workqueue(cbq->pdev->cn_queue); 118 119 kfree(cbq); 120 } 121 122 int cn_cb_equal(struct cb_id *i1, struct cb_id *i2) 123 { 124 return ((i1->idx == i2->idx) && (i1->val == i2->val)); 125 } 126 127 int cn_queue_add_callback(struct cn_queue_dev *dev, char *name, struct cb_id *id, 128 void (*callback)(struct cn_msg *, struct netlink_skb_parms *)) 129 { 130 struct cn_callback_entry *cbq, *__cbq; 131 int found = 0; 132 133 cbq = cn_queue_alloc_callback_entry(name, id, callback); 134 if (!cbq) 135 return -ENOMEM; 136 137 atomic_inc(&dev->refcnt); 138 cbq->pdev = dev; 139 140 spin_lock_bh(&dev->queue_lock); 141 list_for_each_entry(__cbq, &dev->queue_list, callback_entry) { 142 if (cn_cb_equal(&__cbq->id.id, id)) { 143 found = 1; 144 break; 145 } 146 } 147 if (!found) 148 list_add_tail(&cbq->callback_entry, &dev->queue_list); 149 spin_unlock_bh(&dev->queue_lock); 150 151 if (found) { 152 cn_queue_free_callback(cbq); 153 atomic_dec(&dev->refcnt); 154 return -EINVAL; 155 } 156 157 cbq->seq = 0; 158 cbq->group = cbq->id.id.idx; 159 160 return 0; 161 } 162 163 void cn_queue_del_callback(struct cn_queue_dev *dev, struct cb_id *id) 164 { 165 struct cn_callback_entry *cbq, *n; 166 int found = 0; 167 168 spin_lock_bh(&dev->queue_lock); 169 list_for_each_entry_safe(cbq, n, &dev->queue_list, callback_entry) { 170 if (cn_cb_equal(&cbq->id.id, id)) { 171 list_del(&cbq->callback_entry); 172 found = 1; 173 break; 174 } 175 } 176 spin_unlock_bh(&dev->queue_lock); 177 178 if (found) { 179 cn_queue_free_callback(cbq); 180 atomic_dec(&dev->refcnt); 181 } 182 } 183 184 struct cn_queue_dev *cn_queue_alloc_dev(char *name, struct sock *nls) 185 { 186 struct cn_queue_dev *dev; 187 188 dev = kzalloc(sizeof(*dev), GFP_KERNEL); 189 if (!dev) 190 return NULL; 191 192 snprintf(dev->name, sizeof(dev->name), "%s", name); 193 atomic_set(&dev->refcnt, 0); 194 INIT_LIST_HEAD(&dev->queue_list); 195 spin_lock_init(&dev->queue_lock); 196 init_waitqueue_head(&dev->wq_created); 197 198 dev->nls = nls; 199 200 INIT_WORK(&dev->wq_creation, cn_queue_create); 201 202 return dev; 203 } 204 205 void cn_queue_free_dev(struct cn_queue_dev *dev) 206 { 207 struct cn_callback_entry *cbq, *n; 208 long timeout; 209 DEFINE_WAIT(wait); 210 211 /* Flush the first pending jobs queued on kevent */ 212 flush_scheduled_work(); 213 214 /* If the connector workqueue creation is still pending, wait for it */ 215 prepare_to_wait(&dev->wq_created, &wait, TASK_UNINTERRUPTIBLE); 216 if (atomic_read(&dev->wq_requested) && !dev->cn_queue) { 217 timeout = schedule_timeout(HZ * 2); 218 if (!timeout && !dev->cn_queue) 219 WARN_ON(1); 220 } 221 finish_wait(&dev->wq_created, &wait); 222 223 if (dev->cn_queue) { 224 flush_workqueue(dev->cn_queue); 225 destroy_workqueue(dev->cn_queue); 226 } 227 228 spin_lock_bh(&dev->queue_lock); 229 list_for_each_entry_safe(cbq, n, &dev->queue_list, callback_entry) 230 list_del(&cbq->callback_entry); 231 spin_unlock_bh(&dev->queue_lock); 232 233 while (atomic_read(&dev->refcnt)) { 234 printk(KERN_INFO "Waiting for %s to become free: refcnt=%d.\n", 235 dev->name, atomic_read(&dev->refcnt)); 236 msleep(1000); 237 } 238 239 kfree(dev); 240 dev = NULL; 241 } 242