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/notifier.h>
13 #include <linux/mutex.h>
14
15 #include "usb_mon.h"
16 #include "../core/hcd.h"
17
18 static void mon_stop(struct mon_bus *mbus);
19 static void mon_dissolve(struct mon_bus *mbus, struct usb_bus *ubus);
20 static void mon_bus_drop(struct kref *r);
21 static void mon_bus_init(struct usb_bus *ubus);
22
23 DEFINE_MUTEX(mon_lock);
24
25 struct mon_bus mon_bus0; /* Pseudo bus meaning "all buses" */
26 static LIST_HEAD(mon_buses); /* All buses we know: struct mon_bus */
27
28 /*
29 * Link a reader into the bus.
30 *
31 * This must be called with mon_lock taken because of mbus->ref.
32 */
33 void mon_reader_add(struct mon_bus *mbus, struct mon_reader *r)
34 {
35 unsigned long flags;
36 struct list_head *p;
37
38 spin_lock_irqsave(&mbus->lock, flags);
39 if (mbus->nreaders == 0) {
40 if (mbus == &mon_bus0) {
41 list_for_each (p, &mon_buses) {
42 struct mon_bus *m1;
43 m1 = list_entry(p, struct mon_bus, bus_link);
44 m1->u_bus->monitored = 1;
45 }
46 } else {
47 mbus->u_bus->monitored = 1;
48 }
49 }
50 mbus->nreaders++;
51 list_add_tail(&r->r_link, &mbus->r_list);
52 spin_unlock_irqrestore(&mbus->lock, flags);
53
54 kref_get(&mbus->ref);
55 }
56
57 /*
58 * Unlink reader from the bus.
59 *
60 * This is called with mon_lock taken, so we can decrement mbus->ref.
61 */
62 void mon_reader_del(struct mon_bus *mbus, struct mon_reader *r)
63 {
64 unsigned long flags;
65
66 spin_lock_irqsave(&mbus->lock, flags);
67 list_del(&r->r_link);
68 --mbus->nreaders;
69 if (mbus->nreaders == 0)
70 mon_stop(mbus);
71 spin_unlock_irqrestore(&mbus->lock, flags);
72
73 kref_put(&mbus->ref, mon_bus_drop);
74 }
75
76 /*
77 */
78 static void mon_bus_submit(struct mon_bus *mbus, struct urb *urb)
79 {
80 unsigned long flags;
81 struct list_head *pos;
82 struct mon_reader *r;
83
84 spin_lock_irqsave(&mbus->lock, flags);
85 mbus->cnt_events++;
86 list_for_each (pos, &mbus->r_list) {
87 r = list_entry(pos, struct mon_reader, r_link);
88 r->rnf_submit(r->r_data, urb);
89 }
90 spin_unlock_irqrestore(&mbus->lock, flags);
91 return;
92 }
93
94 static void mon_submit(struct usb_bus *ubus, struct urb *urb)
95 {
96 struct mon_bus *mbus;
97
98 if ((mbus = ubus->mon_bus) != NULL)
99 mon_bus_submit(mbus, urb);
100 mon_bus_submit(&mon_bus0, urb);
101 }
102
103 /*
104 */
105 static void mon_bus_submit_error(struct mon_bus *mbus, struct urb *urb, int error)
106 {
107 unsigned long flags;
108 struct list_head *pos;
109 struct mon_reader *r;
110
111 spin_lock_irqsave(&mbus->lock, flags);
112 mbus->cnt_events++;
113 list_for_each (pos, &mbus->r_list) {
114 r = list_entry(pos, struct mon_reader, r_link);
115 r->rnf_error(r->r_data, urb, error);
116 }
117 spin_unlock_irqrestore(&mbus->lock, flags);
118 return;
119 }
120
121 static 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 */
132 static void mon_bus_complete(struct mon_bus *mbus, struct urb *urb,
133 int status)
134 {
135 unsigned long flags;
136 struct list_head *pos;
137 struct mon_reader *r;
138
139 spin_lock_irqsave(&mbus->lock, flags);
140 mbus->cnt_events++;
141 list_for_each (pos, &mbus->r_list) {
142 r = list_entry(pos, struct mon_reader, r_link);
143 r->rnf_complete(r->r_data, urb, status);
144 }
145 spin_unlock_irqrestore(&mbus->lock, flags);
146 }
147
148 static void mon_complete(struct usb_bus *ubus, struct urb *urb, int status)
149 {
150 struct mon_bus *mbus;
151
152 if ((mbus = ubus->mon_bus) != NULL)
153 mon_bus_complete(mbus, urb, status);
154 mon_bus_complete(&mon_bus0, urb, status);
155 }
156
157 /* int (*unlink_urb) (struct urb *urb, int status); */
158
159 /*
160 * Stop monitoring.
161 */
162 static void mon_stop(struct mon_bus *mbus)
163 {
164 struct usb_bus *ubus;
165 struct list_head *p;
166
167 if (mbus == &mon_bus0) {
168 list_for_each (p, &mon_buses) {
169 mbus = list_entry(p, struct mon_bus, bus_link);
170 /*
171 * We do not change nreaders here, so rely on mon_lock.
172 */
173 if (mbus->nreaders == 0 && (ubus = mbus->u_bus) != NULL)
174 ubus->monitored = 0;
175 }
176 } else {
177 /*
178 * A stop can be called for a dissolved mon_bus in case of
179 * a reader staying across an rmmod foo_hcd, so test ->u_bus.
180 */
181 if (mon_bus0.nreaders == 0 && (ubus = mbus->u_bus) != NULL) {
182 ubus->monitored = 0;
183 mb();
184 }
185 }
186 }
187
188 /*
189 * Add a USB bus (usually by a modprobe foo-hcd)
190 *
191 * This does not return an error code because the core cannot care less
192 * if monitoring is not established.
193 */
194 static void mon_bus_add(struct usb_bus *ubus)
195 {
196 mon_bus_init(ubus);
197 mutex_lock(&mon_lock);
198 if (mon_bus0.nreaders != 0)
199 ubus->monitored = 1;
200 mutex_unlock(&mon_lock);
201 }
202
203 /*
204 * Remove a USB bus (either from rmmod foo-hcd or from a hot-remove event).
205 */
206 static void mon_bus_remove(struct usb_bus *ubus)
207 {
208 struct mon_bus *mbus = ubus->mon_bus;
209
210 mutex_lock(&mon_lock);
211 list_del(&mbus->bus_link);
212 if (mbus->text_inited)
213 mon_text_del(mbus);
214 if (mbus->bin_inited)
215 mon_bin_del(mbus);
216
217 mon_dissolve(mbus, ubus);
218 kref_put(&mbus->ref, mon_bus_drop);
219 mutex_unlock(&mon_lock);
220 }
221
222 static int mon_notify(struct notifier_block *self, unsigned long action,
223 void *dev)
224 {
225 switch (action) {
226 case USB_BUS_ADD:
227 mon_bus_add(dev);
228 break;
229 case USB_BUS_REMOVE:
230 mon_bus_remove(dev);
231 }
232 return NOTIFY_OK;
233 }
234
235 static struct notifier_block mon_nb = {
236 .notifier_call = mon_notify,
237 };
238
239 /*
240 * Ops
241 */
242 static struct usb_mon_operations mon_ops_0 = {
243 .urb_submit = mon_submit,
244 .urb_submit_error = mon_submit_error,
245 .urb_complete = mon_complete,
246 };
247
248 /*
249 * Tear usb_bus and mon_bus apart.
250 */
251 static void mon_dissolve(struct mon_bus *mbus, struct usb_bus *ubus)
252 {
253
254 if (ubus->monitored) {
255 ubus->monitored = 0;
256 mb();
257 }
258
259 ubus->mon_bus = NULL;
260 mbus->u_bus = NULL;
261 mb();
262
263 /* We want synchronize_irq() here, but that needs an argument. */
264 }
265
266 /*
267 */
268 static void mon_bus_drop(struct kref *r)
269 {
270 struct mon_bus *mbus = container_of(r, struct mon_bus, ref);
271 kfree(mbus);
272 }
273
274 /*
275 * Initialize a bus for us:
276 * - allocate mon_bus
277 * - refcount USB bus struct
278 * - link
279 */
280 static void mon_bus_init(struct usb_bus *ubus)
281 {
282 struct mon_bus *mbus;
283
284 if ((mbus = kzalloc(sizeof(struct mon_bus), GFP_KERNEL)) == NULL)
285 goto err_alloc;
286 kref_init(&mbus->ref);
287 spin_lock_init(&mbus->lock);
288 INIT_LIST_HEAD(&mbus->r_list);
289
290 /*
291 * We don't need to take a reference to ubus, because we receive
292 * a notification if the bus is about to be removed.
293 */
294 mbus->u_bus = ubus;
295 ubus->mon_bus = mbus;
296
297 mbus->text_inited = mon_text_add(mbus, ubus);
298 mbus->bin_inited = mon_bin_add(mbus, ubus);
299
300 mutex_lock(&mon_lock);
301 list_add_tail(&mbus->bus_link, &mon_buses);
302 mutex_unlock(&mon_lock);
303 return;
304
305 err_alloc:
306 return;
307 }
308
309 static void mon_bus0_init(void)
310 {
311 struct mon_bus *mbus = &mon_bus0;
312
313 kref_init(&mbus->ref);
314 spin_lock_init(&mbus->lock);
315 INIT_LIST_HEAD(&mbus->r_list);
316
317 mbus->text_inited = mon_text_add(mbus, NULL);
318 mbus->bin_inited = mon_bin_add(mbus, NULL);
319 }
320
321 /*
322 * Search a USB bus by number. Notice that USB bus numbers start from one,
323 * which we may later use to identify "all" with zero.
324 *
325 * This function must be called with mon_lock held.
326 *
327 * This is obviously inefficient and may be revised in the future.
328 */
329 struct mon_bus *mon_bus_lookup(unsigned int num)
330 {
331 struct list_head *p;
332 struct mon_bus *mbus;
333
334 if (num == 0) {
335 return &mon_bus0;
336 }
337 list_for_each (p, &mon_buses) {
338 mbus = list_entry(p, struct mon_bus, bus_link);
339 if (mbus->u_bus->busnum == num) {
340 return mbus;
341 }
342 }
343 return NULL;
344 }
345
346 static int __init mon_init(void)
347 {
348 struct usb_bus *ubus;
349 int rc;
350
351 if ((rc = mon_text_init()) != 0)
352 goto err_text;
353 if ((rc = mon_bin_init()) != 0)
354 goto err_bin;
355
356 mon_bus0_init();
357
358 if (usb_mon_register(&mon_ops_0) != 0) {
359 printk(KERN_NOTICE TAG ": unable to register with the core\n");
360 rc = -ENODEV;
361 goto err_reg;
362 }
363 // MOD_INC_USE_COUNT(which_module?);
364
365 usb_register_notify(&mon_nb);
366
367 mutex_lock(&usb_bus_list_lock);
368 list_for_each_entry (ubus, &usb_bus_list, bus_list) {
369 mon_bus_init(ubus);
370 }
371 mutex_unlock(&usb_bus_list_lock);
372 return 0;
373
374 err_reg:
375 mon_bin_exit();
376 err_bin:
377 mon_text_exit();
378 err_text:
379 return rc;
380 }
381
382 static void __exit mon_exit(void)
383 {
384 struct mon_bus *mbus;
385 struct list_head *p;
386
387 usb_unregister_notify(&mon_nb);
388 usb_mon_deregister();
389
390 mutex_lock(&mon_lock);
391
392 while (!list_empty(&mon_buses)) {
393 p = mon_buses.next;
394 mbus = list_entry(p, struct mon_bus, bus_link);
395 list_del(p);
396
397 if (mbus->text_inited)
398 mon_text_del(mbus);
399 if (mbus->bin_inited)
400 mon_bin_del(mbus);
401
402 /*
403 * This never happens, because the open/close paths in
404 * file level maintain module use counters and so rmmod fails
405 * before reaching here. However, better be safe...
406 */
407 if (mbus->nreaders) {
408 printk(KERN_ERR TAG
409 ": Outstanding opens (%d) on usb%d, leaking...\n",
410 mbus->nreaders, mbus->u_bus->busnum);
411 atomic_set(&mbus->ref.refcount, 2); /* Force leak */
412 }
413
414 mon_dissolve(mbus, mbus->u_bus);
415 kref_put(&mbus->ref, mon_bus_drop);
416 }
417
418 mbus = &mon_bus0;
419 if (mbus->text_inited)
420 mon_text_del(mbus);
421 if (mbus->bin_inited)
422 mon_bin_del(mbus);
423
424 mutex_unlock(&mon_lock);
425
426 mon_text_exit();
427 mon_bin_exit();
428 }
429
430 module_init(mon_init);
431 module_exit(mon_exit);
432
433 MODULE_LICENSE("GPL");
434
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