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, 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 } 146 147 static 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 */ 161 static 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 */ 193 static 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 */ 205 static 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 } 220 221 static 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 } 233 234 static struct notifier_block mon_nb = { 235 .notifier_call = mon_notify, 236 }; 237 238 /* 239 * Ops 240 */ 241 static 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 */ 250 static 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 */ 267 static 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 */ 279 static 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; 303 304 err_alloc: 305 return; 306 } 307 308 static 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 */ 328 struct 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 } 344 345 static 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?); 363 364 365 mutex_lock(&usb_bus_list_lock); 366 list_for_each_entry (ubus, &usb_bus_list, bus_list) { 367 mon_bus_init(ubus); 368 } 369 usb_register_notify(&mon_nb); 370 mutex_unlock(&usb_bus_list_lock); 371 return 0; 372 373 err_reg: 374 mon_bin_exit(); 375 err_bin: 376 mon_text_exit(); 377 err_text: 378 return rc; 379 } 380 381 static void __exit mon_exit(void) 382 { 383 struct mon_bus *mbus; 384 struct list_head *p; 385 386 usb_unregister_notify(&mon_nb); 387 usb_mon_deregister(); 388 389 mutex_lock(&mon_lock); 390 391 while (!list_empty(&mon_buses)) { 392 p = mon_buses.next; 393 mbus = list_entry(p, struct mon_bus, bus_link); 394 list_del(p); 395 396 if (mbus->text_inited) 397 mon_text_del(mbus); 398 if (mbus->bin_inited) 399 mon_bin_del(mbus); 400 401 /* 402 * This never happens, because the open/close paths in 403 * file level maintain module use counters and so rmmod fails 404 * before reaching here. However, better be safe... 405 */ 406 if (mbus->nreaders) { 407 printk(KERN_ERR TAG 408 ": Outstanding opens (%d) on usb%d, leaking...\n", 409 mbus->nreaders, mbus->u_bus->busnum); 410 atomic_set(&mbus->ref.refcount, 2); /* Force leak */ 411 } 412 413 mon_dissolve(mbus, mbus->u_bus); 414 kref_put(&mbus->ref, mon_bus_drop); 415 } 416 417 mbus = &mon_bus0; 418 if (mbus->text_inited) 419 mon_text_del(mbus); 420 if (mbus->bin_inited) 421 mon_bin_del(mbus); 422 423 mutex_unlock(&mon_lock); 424 425 mon_text_exit(); 426 mon_bin_exit(); 427 } 428 429 module_init(mon_init); 430 module_exit(mon_exit); 431 432 MODULE_LICENSE("GPL"); 433