timerdev.c

  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
 23static DEFINE_MUTEX(mISDN_mutex);
 24static u_int	*debug;
 25
 26
 27struct 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
 36struct mISDNtimer {
 37	struct list_head	list;
 38	struct  mISDNtimerdev	*dev;
 39	struct timer_list	tl;
 40	int			id;
 41};
 42
 43static int
 44mISDN_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
 63static int
 64mISDN_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
 92static ssize_t
 93mISDN_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
135static __poll_t
136mISDN_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
158static void
159dev_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
171static int
172misdn_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
199static int
200misdn_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
219static long
220mISDN_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
265static 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
274static struct miscdevice mISDNtimer = {
275	.minor	= MISC_DYNAMIC_MINOR,
276	.name	= "mISDNtimer",
277	.fops	= &mISDN_fops,
278};
279
280int
281mISDN_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
292void mISDN_timer_cleanup(void)
293{
294	misc_deregister(&mISDNtimer);
295}