1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 *
4 * general timer device for using in ISDN stacks
5 *
6 * Author Karsten Keil <kkeil@novell.com>
7 *
8 * Copyright 2008 by Karsten Keil <kkeil@novell.com>
9 */
10
11 #include <linux/poll.h>
12 #include <linux/vmalloc.h>
13 #include <linux/slab.h>
14 #include <linux/timer.h>
15 #include <linux/miscdevice.h>
16 #include <linux/module.h>
17 #include <linux/mISDNif.h>
18 #include <linux/mutex.h>
19 #include <linux/sched/signal.h>
20
21 #include "core.h"
22
23 static DEFINE_MUTEX(mISDN_mutex);
24 static u_int *debug;
25
26
27 struct mISDNtimerdev {
28 int next_id;
29 struct list_head pending;
30 struct list_head expired;
31 wait_queue_head_t wait;
32 u_int work;
33 spinlock_t lock; /* protect lists */
34 };
35
36 struct mISDNtimer {
37 struct list_head list;
38 struct mISDNtimerdev *dev;
39 struct timer_list tl;
40 int id;
41 };
42
43 static int
mISDN_open(struct inode * ino,struct file * filep)44 mISDN_open(struct inode *ino, struct file *filep)
45 {
46 struct mISDNtimerdev *dev;
47
48 if (*debug & DEBUG_TIMER)
49 printk(KERN_DEBUG "%s(%p,%p)\n", __func__, ino, filep);
50 dev = kmalloc(sizeof(struct mISDNtimerdev) , GFP_KERNEL);
51 if (!dev)
52 return -ENOMEM;
53 dev->next_id = 1;
54 INIT_LIST_HEAD(&dev->pending);
55 INIT_LIST_HEAD(&dev->expired);
56 spin_lock_init(&dev->lock);
57 dev->work = 0;
58 init_waitqueue_head(&dev->wait);
59 filep->private_data = dev;
60 return nonseekable_open(ino, filep);
61 }
62
63 static int
mISDN_close(struct inode * ino,struct file * filep)64 mISDN_close(struct inode *ino, struct file *filep)
65 {
66 struct mISDNtimerdev *dev = filep->private_data;
67 struct list_head *list = &dev->pending;
68 struct mISDNtimer *timer, *next;
69
70 if (*debug & DEBUG_TIMER)
71 printk(KERN_DEBUG "%s(%p,%p)\n", __func__, ino, filep);
72
73 spin_lock_irq(&dev->lock);
74 while (!list_empty(list)) {
75 timer = list_first_entry(list, struct mISDNtimer, list);
76 spin_unlock_irq(&dev->lock);
77 timer_shutdown_sync(&timer->tl);
78 spin_lock_irq(&dev->lock);
79 /* it might have been moved to ->expired */
80 list_del(&timer->list);
81 kfree(timer);
82 }
83 spin_unlock_irq(&dev->lock);
84
85 list_for_each_entry_safe(timer, next, &dev->expired, list) {
86 kfree(timer);
87 }
88 kfree(dev);
89 return 0;
90 }
91
92 static ssize_t
mISDN_read(struct file * filep,char __user * buf,size_t count,loff_t * off)93 mISDN_read(struct file *filep, char __user *buf, size_t count, loff_t *off)
94 {
95 struct mISDNtimerdev *dev = filep->private_data;
96 struct list_head *list = &dev->expired;
97 struct mISDNtimer *timer;
98 int ret = 0;
99
100 if (*debug & DEBUG_TIMER)
101 printk(KERN_DEBUG "%s(%p, %p, %d, %p)\n", __func__,
102 filep, buf, (int)count, off);
103
104 if (count < sizeof(int))
105 return -ENOSPC;
106
107 spin_lock_irq(&dev->lock);
108 while (list_empty(list) && (dev->work == 0)) {
109 spin_unlock_irq(&dev->lock);
110 if (filep->f_flags & O_NONBLOCK)
111 return -EAGAIN;
112 wait_event_interruptible(dev->wait, (READ_ONCE(dev->work) ||
113 !list_empty(list)));
114 if (signal_pending(current))
115 return -ERESTARTSYS;
116 spin_lock_irq(&dev->lock);
117 }
118 if (dev->work)
119 WRITE_ONCE(dev->work, 0);
120 if (!list_empty(list)) {
121 timer = list_first_entry(list, struct mISDNtimer, list);
122 list_del(&timer->list);
123 spin_unlock_irq(&dev->lock);
124 if (put_user(timer->id, (int __user *)buf))
125 ret = -EFAULT;
126 else
127 ret = sizeof(int);
128 kfree(timer);
129 } else {
130 spin_unlock_irq(&dev->lock);
131 }
132 return ret;
133 }
134
135 static __poll_t
mISDN_poll(struct file * filep,poll_table * wait)136 mISDN_poll(struct file *filep, poll_table *wait)
137 {
138 struct mISDNtimerdev *dev = filep->private_data;
139 __poll_t mask = EPOLLERR;
140
141 if (*debug & DEBUG_TIMER)
142 printk(KERN_DEBUG "%s(%p, %p)\n", __func__, filep, wait);
143 if (dev) {
144 u32 work;
145
146 poll_wait(filep, &dev->wait, wait);
147 mask = 0;
148 work = READ_ONCE(dev->work);
149 if (work || !list_empty(&dev->expired))
150 mask |= (EPOLLIN | EPOLLRDNORM);
151 if (*debug & DEBUG_TIMER)
152 printk(KERN_DEBUG "%s work(%d) empty(%d)\n", __func__,
153 work, list_empty(&dev->expired));
154 }
155 return mask;
156 }
157
158 static void
dev_expire_timer(struct timer_list * t)159 dev_expire_timer(struct timer_list *t)
160 {
161 struct mISDNtimer *timer = timer_container_of(timer, t, tl);
162 u_long flags;
163
164 spin_lock_irqsave(&timer->dev->lock, flags);
165 if (timer->id >= 0)
166 list_move_tail(&timer->list, &timer->dev->expired);
167 wake_up_interruptible(&timer->dev->wait);
168 spin_unlock_irqrestore(&timer->dev->lock, flags);
169 }
170
171 static int
misdn_add_timer(struct mISDNtimerdev * dev,int timeout)172 misdn_add_timer(struct mISDNtimerdev *dev, int timeout)
173 {
174 int id;
175 struct mISDNtimer *timer;
176
177 if (!timeout) {
178 WRITE_ONCE(dev->work, 1);
179 wake_up_interruptible(&dev->wait);
180 id = 0;
181 } else {
182 timer = kzalloc(sizeof(struct mISDNtimer), GFP_KERNEL);
183 if (!timer)
184 return -ENOMEM;
185 timer->dev = dev;
186 timer_setup(&timer->tl, dev_expire_timer, 0);
187 spin_lock_irq(&dev->lock);
188 id = timer->id = dev->next_id++;
189 if (dev->next_id < 0)
190 dev->next_id = 1;
191 list_add_tail(&timer->list, &dev->pending);
192 timer->tl.expires = jiffies + ((HZ * (u_long)timeout) / 1000);
193 add_timer(&timer->tl);
194 spin_unlock_irq(&dev->lock);
195 }
196 return id;
197 }
198
199 static int
misdn_del_timer(struct mISDNtimerdev * dev,int id)200 misdn_del_timer(struct mISDNtimerdev *dev, int id)
201 {
202 struct mISDNtimer *timer;
203
204 spin_lock_irq(&dev->lock);
205 list_for_each_entry(timer, &dev->pending, list) {
206 if (timer->id == id) {
207 list_del_init(&timer->list);
208 timer->id = -1;
209 spin_unlock_irq(&dev->lock);
210 timer_shutdown_sync(&timer->tl);
211 kfree(timer);
212 return id;
213 }
214 }
215 spin_unlock_irq(&dev->lock);
216 return 0;
217 }
218
219 static long
mISDN_ioctl(struct file * filep,unsigned int cmd,unsigned long arg)220 mISDN_ioctl(struct file *filep, unsigned int cmd, unsigned long arg)
221 {
222 struct mISDNtimerdev *dev = filep->private_data;
223 int id, tout, ret = 0;
224
225
226 if (*debug & DEBUG_TIMER)
227 printk(KERN_DEBUG "%s(%p, %x, %lx)\n", __func__,
228 filep, cmd, arg);
229 mutex_lock(&mISDN_mutex);
230 switch (cmd) {
231 case IMADDTIMER:
232 if (get_user(tout, (int __user *)arg)) {
233 ret = -EFAULT;
234 break;
235 }
236 id = misdn_add_timer(dev, tout);
237 if (*debug & DEBUG_TIMER)
238 printk(KERN_DEBUG "%s add %d id %d\n", __func__,
239 tout, id);
240 if (id < 0) {
241 ret = id;
242 break;
243 }
244 if (put_user(id, (int __user *)arg))
245 ret = -EFAULT;
246 break;
247 case IMDELTIMER:
248 if (get_user(id, (int __user *)arg)) {
249 ret = -EFAULT;
250 break;
251 }
252 if (*debug & DEBUG_TIMER)
253 printk(KERN_DEBUG "%s del id %d\n", __func__, id);
254 id = misdn_del_timer(dev, id);
255 if (put_user(id, (int __user *)arg))
256 ret = -EFAULT;
257 break;
258 default:
259 ret = -EINVAL;
260 }
261 mutex_unlock(&mISDN_mutex);
262 return ret;
263 }
264
265 static const struct file_operations mISDN_fops = {
266 .owner = THIS_MODULE,
267 .read = mISDN_read,
268 .poll = mISDN_poll,
269 .unlocked_ioctl = mISDN_ioctl,
270 .open = mISDN_open,
271 .release = mISDN_close,
272 };
273
274 static struct miscdevice mISDNtimer = {
275 .minor = MISC_DYNAMIC_MINOR,
276 .name = "mISDNtimer",
277 .fops = &mISDN_fops,
278 };
279
280 int
mISDN_inittimer(u_int * deb)281 mISDN_inittimer(u_int *deb)
282 {
283 int err;
284
285 debug = deb;
286 err = misc_register(&mISDNtimer);
287 if (err)
288 printk(KERN_WARNING "mISDN: Could not register timer device\n");
289 return err;
290 }
291
mISDN_timer_cleanup(void)292 void mISDN_timer_cleanup(void)
293 {
294 misc_deregister(&mISDNtimer);
295 }
296