1 /* 2 * cn_queue.c 3 * 4 * 2004-2005 Copyright (c) Evgeniy Polyakov <johnpol@2ka.mipt.ru> 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 *cn_queue_alloc_callback_entry(char *name, struct cb_id *id, void (*callback)(void *)) 91 { 92 struct cn_callback_entry *cbq; 93 94 cbq = kzalloc(sizeof(*cbq), GFP_KERNEL); 95 if (!cbq) { 96 printk(KERN_ERR "Failed to create new callback queue.\n"); 97 return NULL; 98 } 99 100 snprintf(cbq->id.name, sizeof(cbq->id.name), "%s", name); 101 memcpy(&cbq->id.id, id, sizeof(struct cb_id)); 102 cbq->data.callback = callback; 103 104 INIT_WORK(&cbq->work, &cn_queue_wrapper); 105 return cbq; 106 } 107 108 static void cn_queue_free_callback(struct cn_callback_entry *cbq) 109 { 110 /* The first jobs have been sent to kevent, flush them too */ 111 flush_scheduled_work(); 112 if (cbq->pdev->cn_queue) 113 flush_workqueue(cbq->pdev->cn_queue); 114 115 kfree(cbq); 116 } 117 118 int cn_cb_equal(struct cb_id *i1, struct cb_id *i2) 119 { 120 return ((i1->idx == i2->idx) && (i1->val == i2->val)); 121 } 122 123 int cn_queue_add_callback(struct cn_queue_dev *dev, char *name, struct cb_id *id, void (*callback)(void *)) 124 { 125 struct cn_callback_entry *cbq, *__cbq; 126 int found = 0; 127 128 cbq = cn_queue_alloc_callback_entry(name, id, callback); 129 if (!cbq) 130 return -ENOMEM; 131 132 atomic_inc(&dev->refcnt); 133 cbq->pdev = dev; 134 135 spin_lock_bh(&dev->queue_lock); 136 list_for_each_entry(__cbq, &dev->queue_list, callback_entry) { 137 if (cn_cb_equal(&__cbq->id.id, id)) { 138 found = 1; 139 break; 140 } 141 } 142 if (!found) 143 list_add_tail(&cbq->callback_entry, &dev->queue_list); 144 spin_unlock_bh(&dev->queue_lock); 145 146 if (found) { 147 cn_queue_free_callback(cbq); 148 atomic_dec(&dev->refcnt); 149 return -EINVAL; 150 } 151 152 cbq->seq = 0; 153 cbq->group = cbq->id.id.idx; 154 155 return 0; 156 } 157 158 void cn_queue_del_callback(struct cn_queue_dev *dev, struct cb_id *id) 159 { 160 struct cn_callback_entry *cbq, *n; 161 int found = 0; 162 163 spin_lock_bh(&dev->queue_lock); 164 list_for_each_entry_safe(cbq, n, &dev->queue_list, callback_entry) { 165 if (cn_cb_equal(&cbq->id.id, id)) { 166 list_del(&cbq->callback_entry); 167 found = 1; 168 break; 169 } 170 } 171 spin_unlock_bh(&dev->queue_lock); 172 173 if (found) { 174 cn_queue_free_callback(cbq); 175 atomic_dec(&dev->refcnt); 176 } 177 } 178 179 struct cn_queue_dev *cn_queue_alloc_dev(char *name, struct sock *nls) 180 { 181 struct cn_queue_dev *dev; 182 183 dev = kzalloc(sizeof(*dev), GFP_KERNEL); 184 if (!dev) 185 return NULL; 186 187 snprintf(dev->name, sizeof(dev->name), "%s", name); 188 atomic_set(&dev->refcnt, 0); 189 INIT_LIST_HEAD(&dev->queue_list); 190 spin_lock_init(&dev->queue_lock); 191 init_waitqueue_head(&dev->wq_created); 192 193 dev->nls = nls; 194 195 INIT_WORK(&dev->wq_creation, cn_queue_create); 196 197 return dev; 198 } 199 200 void cn_queue_free_dev(struct cn_queue_dev *dev) 201 { 202 struct cn_callback_entry *cbq, *n; 203 long timeout; 204 DEFINE_WAIT(wait); 205 206 /* Flush the first pending jobs queued on kevent */ 207 flush_scheduled_work(); 208 209 /* If the connector workqueue creation is still pending, wait for it */ 210 prepare_to_wait(&dev->wq_created, &wait, TASK_UNINTERRUPTIBLE); 211 if (atomic_read(&dev->wq_requested) && !dev->cn_queue) { 212 timeout = schedule_timeout(HZ * 2); 213 if (!timeout && !dev->cn_queue) 214 WARN_ON(1); 215 } 216 finish_wait(&dev->wq_created, &wait); 217 218 if (dev->cn_queue) { 219 flush_workqueue(dev->cn_queue); 220 destroy_workqueue(dev->cn_queue); 221 } 222 223 spin_lock_bh(&dev->queue_lock); 224 list_for_each_entry_safe(cbq, n, &dev->queue_list, callback_entry) 225 list_del(&cbq->callback_entry); 226 spin_unlock_bh(&dev->queue_lock); 227 228 while (atomic_read(&dev->refcnt)) { 229 printk(KERN_INFO "Waiting for %s to become free: refcnt=%d.\n", 230 dev->name, atomic_read(&dev->refcnt)); 231 msleep(1000); 232 } 233 234 kfree(dev); 235 dev = NULL; 236 } 237