1 /* 2 * cn_queue.c 3 * 4 * 2004+ Copyright (c) Evgeniy Polyakov <[email protected]> 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 83 d->callback(msg); 84 85 d->destruct_data(d->ddata); 86 d->ddata = NULL; 87 88 kfree(d->free); 89 } 90 91 static struct cn_callback_entry * 92 cn_queue_alloc_callback_entry(char *name, struct cb_id *id, 93 void (*callback)(struct cn_msg *)) 94 { 95 struct cn_callback_entry *cbq; 96 97 cbq = kzalloc(sizeof(*cbq), GFP_KERNEL); 98 if (!cbq) { 99 printk(KERN_ERR "Failed to create new callback queue.\n"); 100 return NULL; 101 } 102 103 snprintf(cbq->id.name, sizeof(cbq->id.name), "%s", name); 104 memcpy(&cbq->id.id, id, sizeof(struct cb_id)); 105 cbq->data.callback = callback; 106 107 INIT_WORK(&cbq->work, &cn_queue_wrapper); 108 return cbq; 109 } 110 111 static void cn_queue_free_callback(struct cn_callback_entry *cbq) 112 { 113 /* The first jobs have been sent to kevent, flush them too */ 114 flush_scheduled_work(); 115 if (cbq->pdev->cn_queue) 116 flush_workqueue(cbq->pdev->cn_queue); 117 118 kfree(cbq); 119 } 120 121 int cn_cb_equal(struct cb_id *i1, struct cb_id *i2) 122 { 123 return ((i1->idx == i2->idx) && (i1->val == i2->val)); 124 } 125 126 int cn_queue_add_callback(struct cn_queue_dev *dev, char *name, struct cb_id *id, 127 void (*callback)(struct cn_msg *)) 128 { 129 struct cn_callback_entry *cbq, *__cbq; 130 int found = 0; 131 132 cbq = cn_queue_alloc_callback_entry(name, id, callback); 133 if (!cbq) 134 return -ENOMEM; 135 136 atomic_inc(&dev->refcnt); 137 cbq->pdev = dev; 138 139 spin_lock_bh(&dev->queue_lock); 140 list_for_each_entry(__cbq, &dev->queue_list, callback_entry) { 141 if (cn_cb_equal(&__cbq->id.id, id)) { 142 found = 1; 143 break; 144 } 145 } 146 if (!found) 147 list_add_tail(&cbq->callback_entry, &dev->queue_list); 148 spin_unlock_bh(&dev->queue_lock); 149 150 if (found) { 151 cn_queue_free_callback(cbq); 152 atomic_dec(&dev->refcnt); 153 return -EINVAL; 154 } 155 156 cbq->seq = 0; 157 cbq->group = cbq->id.id.idx; 158 159 return 0; 160 } 161 162 void cn_queue_del_callback(struct cn_queue_dev *dev, struct cb_id *id) 163 { 164 struct cn_callback_entry *cbq, *n; 165 int found = 0; 166 167 spin_lock_bh(&dev->queue_lock); 168 list_for_each_entry_safe(cbq, n, &dev->queue_list, callback_entry) { 169 if (cn_cb_equal(&cbq->id.id, id)) { 170 list_del(&cbq->callback_entry); 171 found = 1; 172 break; 173 } 174 } 175 spin_unlock_bh(&dev->queue_lock); 176 177 if (found) { 178 cn_queue_free_callback(cbq); 179 atomic_dec(&dev->refcnt); 180 } 181 } 182 183 struct cn_queue_dev *cn_queue_alloc_dev(char *name, struct sock *nls) 184 { 185 struct cn_queue_dev *dev; 186 187 dev = kzalloc(sizeof(*dev), GFP_KERNEL); 188 if (!dev) 189 return NULL; 190 191 snprintf(dev->name, sizeof(dev->name), "%s", name); 192 atomic_set(&dev->refcnt, 0); 193 INIT_LIST_HEAD(&dev->queue_list); 194 spin_lock_init(&dev->queue_lock); 195 init_waitqueue_head(&dev->wq_created); 196 197 dev->nls = nls; 198 199 INIT_WORK(&dev->wq_creation, cn_queue_create); 200 201 return dev; 202 } 203 204 void cn_queue_free_dev(struct cn_queue_dev *dev) 205 { 206 struct cn_callback_entry *cbq, *n; 207 long timeout; 208 DEFINE_WAIT(wait); 209 210 /* Flush the first pending jobs queued on kevent */ 211 flush_scheduled_work(); 212 213 /* If the connector workqueue creation is still pending, wait for it */ 214 prepare_to_wait(&dev->wq_created, &wait, TASK_UNINTERRUPTIBLE); 215 if (atomic_read(&dev->wq_requested) && !dev->cn_queue) { 216 timeout = schedule_timeout(HZ * 2); 217 if (!timeout && !dev->cn_queue) 218 WARN_ON(1); 219 } 220 finish_wait(&dev->wq_created, &wait); 221 222 if (dev->cn_queue) { 223 flush_workqueue(dev->cn_queue); 224 destroy_workqueue(dev->cn_queue); 225 } 226 227 spin_lock_bh(&dev->queue_lock); 228 list_for_each_entry_safe(cbq, n, &dev->queue_list, callback_entry) 229 list_del(&cbq->callback_entry); 230 spin_unlock_bh(&dev->queue_lock); 231 232 while (atomic_read(&dev->refcnt)) { 233 printk(KERN_INFO "Waiting for %s to become free: refcnt=%d.\n", 234 dev->name, atomic_read(&dev->refcnt)); 235 msleep(1000); 236 } 237 238 kfree(dev); 239 dev = NULL; 240 } 241