1/*
2 * The USB Monitor, inspired by Dave Harding's USBMon.
3 *
4 * mon_main.c: Main file, module initiation and exit, registrations, etc.
5 *
6 * Copyright (C) 2005 Pete Zaitcev (zaitcev@redhat.com)
7 */
8
9#include <linux/kernel.h>
10#include <linux/module.h>
11#include <linux/usb.h>
12#include <linux/usb/hcd.h>
13#include <linux/slab.h>
14#include <linux/notifier.h>
15#include <linux/mutex.h>
16
17#include "usb_mon.h"
18
19
20static void mon_stop(struct mon_bus *mbus);
21static void mon_dissolve(struct mon_bus *mbus, struct usb_bus *ubus);
22static void mon_bus_drop(struct kref *r);
23static void mon_bus_init(struct usb_bus *ubus);
24
25DEFINE_MUTEX(mon_lock);
26
27struct mon_bus mon_bus0;		/* Pseudo bus meaning "all buses" */
28static LIST_HEAD(mon_buses);		/* All buses we know: struct mon_bus */
29
30/*
31 * Link a reader into the bus.
32 *
33 * This must be called with mon_lock taken because of mbus->ref.
34 */
35void mon_reader_add(struct mon_bus *mbus, struct mon_reader *r)
36{
37	unsigned long flags;
38	struct list_head *p;
39
40	spin_lock_irqsave(&mbus->lock, flags);
41	if (mbus->nreaders == 0) {
42		if (mbus == &mon_bus0) {
43			list_for_each (p, &mon_buses) {
44				struct mon_bus *m1;
45				m1 = list_entry(p, struct mon_bus, bus_link);
46				m1->u_bus->monitored = 1;
47			}
48		} else {
49			mbus->u_bus->monitored = 1;
50		}
51	}
52	mbus->nreaders++;
53	list_add_tail(&r->r_link, &mbus->r_list);
54	spin_unlock_irqrestore(&mbus->lock, flags);
55
56	kref_get(&mbus->ref);
57}
58
59/*
60 * Unlink reader from the bus.
61 *
62 * This is called with mon_lock taken, so we can decrement mbus->ref.
63 */
64void mon_reader_del(struct mon_bus *mbus, struct mon_reader *r)
65{
66	unsigned long flags;
67
68	spin_lock_irqsave(&mbus->lock, flags);
69	list_del(&r->r_link);
70	--mbus->nreaders;
71	if (mbus->nreaders == 0)
72		mon_stop(mbus);
73	spin_unlock_irqrestore(&mbus->lock, flags);
74
75	kref_put(&mbus->ref, mon_bus_drop);
76}
77
78/*
79 */
80static void mon_bus_submit(struct mon_bus *mbus, struct urb *urb)
81{
82	unsigned long flags;
83	struct list_head *pos;
84	struct mon_reader *r;
85
86	spin_lock_irqsave(&mbus->lock, flags);
87	mbus->cnt_events++;
88	list_for_each (pos, &mbus->r_list) {
89		r = list_entry(pos, struct mon_reader, r_link);
90		r->rnf_submit(r->r_data, urb);
91	}
92	spin_unlock_irqrestore(&mbus->lock, flags);
93}
94
95static void mon_submit(struct usb_bus *ubus, struct urb *urb)
96{
97	struct mon_bus *mbus;
98
99	if ((mbus = ubus->mon_bus) != NULL)
100		mon_bus_submit(mbus, urb);
101	mon_bus_submit(&mon_bus0, urb);
102}
103
104/*
105 */
106static void mon_bus_submit_error(struct mon_bus *mbus, struct urb *urb, int error)
107{
108	unsigned long flags;
109	struct list_head *pos;
110	struct mon_reader *r;
111
112	spin_lock_irqsave(&mbus->lock, flags);
113	mbus->cnt_events++;
114	list_for_each (pos, &mbus->r_list) {
115		r = list_entry(pos, struct mon_reader, r_link);
116		r->rnf_error(r->r_data, urb, error);
117	}
118	spin_unlock_irqrestore(&mbus->lock, flags);
119}
120
121static void mon_submit_error(struct usb_bus *ubus, struct urb *urb, int error)
122{
123	struct mon_bus *mbus;
124
125	if ((mbus = ubus->mon_bus) != NULL)
126		mon_bus_submit_error(mbus, urb, error);
127	mon_bus_submit_error(&mon_bus0, urb, error);
128}
129
130/*
131 */
132static void mon_bus_complete(struct mon_bus *mbus, struct urb *urb, int status)
133{
134	unsigned long flags;
135	struct list_head *pos;
136	struct mon_reader *r;
137
138	spin_lock_irqsave(&mbus->lock, flags);
139	mbus->cnt_events++;
140	list_for_each (pos, &mbus->r_list) {
141		r = list_entry(pos, struct mon_reader, r_link);
142		r->rnf_complete(r->r_data, urb, status);
143	}
144	spin_unlock_irqrestore(&mbus->lock, flags);
145}
146
147static void mon_complete(struct usb_bus *ubus, struct urb *urb, int status)
148{
149	struct mon_bus *mbus;
150
151	if ((mbus = ubus->mon_bus) != NULL)
152		mon_bus_complete(mbus, urb, status);
153	mon_bus_complete(&mon_bus0, urb, status);
154}
155
156/* int (*unlink_urb) (struct urb *urb, int status); */
157
158/*
159 * Stop monitoring.
160 */
161static void mon_stop(struct mon_bus *mbus)
162{
163	struct usb_bus *ubus;
164	struct list_head *p;
165
166	if (mbus == &mon_bus0) {
167		list_for_each (p, &mon_buses) {
168			mbus = list_entry(p, struct mon_bus, bus_link);
169			/*
170			 * We do not change nreaders here, so rely on mon_lock.
171			 */
172			if (mbus->nreaders == 0 && (ubus = mbus->u_bus) != NULL)
173				ubus->monitored = 0;
174		}
175	} else {
176		/*
177		 * A stop can be called for a dissolved mon_bus in case of
178		 * a reader staying across an rmmod foo_hcd, so test ->u_bus.
179		 */
180		if (mon_bus0.nreaders == 0 && (ubus = mbus->u_bus) != NULL) {
181			ubus->monitored = 0;
182			mb();
183		}
184	}
185}
186
187/*
188 * Add a USB bus (usually by a modprobe foo-hcd)
189 *
190 * This does not return an error code because the core cannot care less
191 * if monitoring is not established.
192 */
193static void mon_bus_add(struct usb_bus *ubus)
194{
195	mon_bus_init(ubus);
196	mutex_lock(&mon_lock);
197	if (mon_bus0.nreaders != 0)
198		ubus->monitored = 1;
199	mutex_unlock(&mon_lock);
200}
201
202/*
203 * Remove a USB bus (either from rmmod foo-hcd or from a hot-remove event).
204 */
205static void mon_bus_remove(struct usb_bus *ubus)
206{
207	struct mon_bus *mbus = ubus->mon_bus;
208
209	mutex_lock(&mon_lock);
210	list_del(&mbus->bus_link);
211	if (mbus->text_inited)
212		mon_text_del(mbus);
213	if (mbus->bin_inited)
214		mon_bin_del(mbus);
215
216	mon_dissolve(mbus, ubus);
217	kref_put(&mbus->ref, mon_bus_drop);
218	mutex_unlock(&mon_lock);
219}
220
221static int mon_notify(struct notifier_block *self, unsigned long action,
222		      void *dev)
223{
224	switch (action) {
225	case USB_BUS_ADD:
226		mon_bus_add(dev);
227		break;
228	case USB_BUS_REMOVE:
229		mon_bus_remove(dev);
230	}
231	return NOTIFY_OK;
232}
233
234static struct notifier_block mon_nb = {
235	.notifier_call = 	mon_notify,
236};
237
238/*
239 * Ops
240 */
241static struct usb_mon_operations mon_ops_0 = {
242	.urb_submit =	mon_submit,
243	.urb_submit_error = mon_submit_error,
244	.urb_complete =	mon_complete,
245};
246
247/*
248 * Tear usb_bus and mon_bus apart.
249 */
250static void mon_dissolve(struct mon_bus *mbus, struct usb_bus *ubus)
251{
252
253	if (ubus->monitored) {
254		ubus->monitored = 0;
255		mb();
256	}
257
258	ubus->mon_bus = NULL;
259	mbus->u_bus = NULL;
260	mb();
261
262	/* We want synchronize_irq() here, but that needs an argument. */
263}
264
265/*
266 */
267static void mon_bus_drop(struct kref *r)
268{
269	struct mon_bus *mbus = container_of(r, struct mon_bus, ref);
270	kfree(mbus);
271}
272
273/*
274 * Initialize a bus for us:
275 *  - allocate mon_bus
276 *  - refcount USB bus struct
277 *  - link
278 */
279static void mon_bus_init(struct usb_bus *ubus)
280{
281	struct mon_bus *mbus;
282
283	if ((mbus = kzalloc(sizeof(struct mon_bus), GFP_KERNEL)) == NULL)
284		goto err_alloc;
285	kref_init(&mbus->ref);
286	spin_lock_init(&mbus->lock);
287	INIT_LIST_HEAD(&mbus->r_list);
288
289	/*
290	 * We don't need to take a reference to ubus, because we receive
291	 * a notification if the bus is about to be removed.
292	 */
293	mbus->u_bus = ubus;
294	ubus->mon_bus = mbus;
295
296	mbus->text_inited = mon_text_add(mbus, ubus);
297	mbus->bin_inited = mon_bin_add(mbus, ubus);
298
299	mutex_lock(&mon_lock);
300	list_add_tail(&mbus->bus_link, &mon_buses);
301	mutex_unlock(&mon_lock);
302	return;
303
304err_alloc:
305	return;
306}
307
308static void mon_bus0_init(void)
309{
310	struct mon_bus *mbus = &mon_bus0;
311
312	kref_init(&mbus->ref);
313	spin_lock_init(&mbus->lock);
314	INIT_LIST_HEAD(&mbus->r_list);
315
316	mbus->text_inited = mon_text_add(mbus, NULL);
317	mbus->bin_inited = mon_bin_add(mbus, NULL);
318}
319
320/*
321 * Search a USB bus by number. Notice that USB bus numbers start from one,
322 * which we may later use to identify "all" with zero.
323 *
324 * This function must be called with mon_lock held.
325 *
326 * This is obviously inefficient and may be revised in the future.
327 */
328struct mon_bus *mon_bus_lookup(unsigned int num)
329{
330	struct list_head *p;
331	struct mon_bus *mbus;
332
333	if (num == 0) {
334		return &mon_bus0;
335	}
336	list_for_each (p, &mon_buses) {
337		mbus = list_entry(p, struct mon_bus, bus_link);
338		if (mbus->u_bus->busnum == num) {
339			return mbus;
340		}
341	}
342	return NULL;
343}
344
345static int __init mon_init(void)
346{
347	struct usb_bus *ubus;
348	int rc;
349
350	if ((rc = mon_text_init()) != 0)
351		goto err_text;
352	if ((rc = mon_bin_init()) != 0)
353		goto err_bin;
354
355	mon_bus0_init();
356
357	if (usb_mon_register(&mon_ops_0) != 0) {
358		printk(KERN_NOTICE TAG ": unable to register with the core\n");
359		rc = -ENODEV;
360		goto err_reg;
361	}
362	// MOD_INC_USE_COUNT(which_module?);
363
364	mutex_lock(&usb_bus_list_lock);
365	list_for_each_entry (ubus, &usb_bus_list, bus_list) {
366		mon_bus_init(ubus);
367	}
368	usb_register_notify(&mon_nb);
369	mutex_unlock(&usb_bus_list_lock);
370	return 0;
371
372err_reg:
373	mon_bin_exit();
374err_bin:
375	mon_text_exit();
376err_text:
377	return rc;
378}
379
380static void __exit mon_exit(void)
381{
382	struct mon_bus *mbus;
383	struct list_head *p;
384
385	usb_unregister_notify(&mon_nb);
386	usb_mon_deregister();
387
388	mutex_lock(&mon_lock);
389
390	while (!list_empty(&mon_buses)) {
391		p = mon_buses.next;
392		mbus = list_entry(p, struct mon_bus, bus_link);
393		list_del(p);
394
395		if (mbus->text_inited)
396			mon_text_del(mbus);
397		if (mbus->bin_inited)
398			mon_bin_del(mbus);
399
400		/*
401		 * This never happens, because the open/close paths in
402		 * file level maintain module use counters and so rmmod fails
403		 * before reaching here. However, better be safe...
404		 */
405		if (mbus->nreaders) {
406			printk(KERN_ERR TAG
407			    ": Outstanding opens (%d) on usb%d, leaking...\n",
408			    mbus->nreaders, mbus->u_bus->busnum);
409			atomic_set(&mbus->ref.refcount, 2);	/* Force leak */
410		}
411
412		mon_dissolve(mbus, mbus->u_bus);
413		kref_put(&mbus->ref, mon_bus_drop);
414	}
415
416	mbus = &mon_bus0;
417	if (mbus->text_inited)
418		mon_text_del(mbus);
419	if (mbus->bin_inited)
420		mon_bin_del(mbus);
421
422	mutex_unlock(&mon_lock);
423
424	mon_text_exit();
425	mon_bin_exit();
426}
427
428module_init(mon_init);
429module_exit(mon_exit);
430
431MODULE_LICENSE("GPL");
432