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