drivers/usb/mon/mon_main.c

   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
  20 static void mon_stop(struct mon_bus *mbus);
  21 static void mon_dissolve(struct mon_bus *mbus, struct usb_bus *ubus);
  22 static void mon_bus_drop(struct kref *r);
  23 static void mon_bus_init(struct usb_bus *ubus);
  24
  25 DEFINE_MUTEX(mon_lock);
  26
  27 struct mon_bus mon_bus0;                /* Pseudo bus meaning "all buses" */
  28 static 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  */
  35 void 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  */
  64 void 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  */
  80 static 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
  95 static void mon_submit(struct usb_bus *ubus, struct urb *urb)
  96 {
  97         struct mon_bus *mbus;
  98
  99         mbus = ubus->mon_bus;
 100         if (mbus != NULL)
 101                 mon_bus_submit(mbus, urb);
 102         mon_bus_submit(&mon_bus0, urb);
 103 }
 104
 105 /*
 106  */
 107 static void mon_bus_submit_error(struct mon_bus *mbus, struct urb *urb, int error)
 108 {
 109         unsigned long flags;
 110         struct list_head *pos;
 111         struct mon_reader *r;
 112
 113         spin_lock_irqsave(&mbus->lock, flags);
 114         mbus->cnt_events++;
 115         list_for_each (pos, &mbus->r_list) {
 116                 r = list_entry(pos, struct mon_reader, r_link);
 117                 r->rnf_error(r->r_data, urb, error);
 118         }
 119         spin_unlock_irqrestore(&mbus->lock, flags);
 120 }
 121
 122 static void mon_submit_error(struct usb_bus *ubus, struct urb *urb, int error)
 123 {
 124         struct mon_bus *mbus;
 125
 126         mbus = ubus->mon_bus;
 127         if (mbus != NULL)
 128                 mon_bus_submit_error(mbus, urb, error);
 129         mon_bus_submit_error(&mon_bus0, urb, error);
 130 }
 131
 132 /*
 133  */
 134 static void mon_bus_complete(struct mon_bus *mbus, struct urb *urb, int status)
 135 {
 136         unsigned long flags;
 137         struct list_head *pos;
 138         struct mon_reader *r;
 139
 140         spin_lock_irqsave(&mbus->lock, flags);
 141         mbus->cnt_events++;
 142         list_for_each (pos, &mbus->r_list) {
 143                 r = list_entry(pos, struct mon_reader, r_link);
 144                 r->rnf_complete(r->r_data, urb, status);
 145         }
 146         spin_unlock_irqrestore(&mbus->lock, flags);
 147 }
 148
 149 static void mon_complete(struct usb_bus *ubus, struct urb *urb, int status)
 150 {
 151         struct mon_bus *mbus;
 152
 153         mbus = ubus->mon_bus;
 154         if (mbus != NULL)
 155                 mon_bus_complete(mbus, urb, status);
 156         mon_bus_complete(&mon_bus0, urb, status);
 157 }
 158
 159 /* int (*unlink_urb) (struct urb *urb, int status); */
 160
 161 /*
 162  * Stop monitoring.
 163  */
 164 static void mon_stop(struct mon_bus *mbus)
 165 {
 166         struct usb_bus *ubus;
 167         struct list_head *p;
 168
 169         if (mbus == &mon_bus0) {
 170                 list_for_each (p, &mon_buses) {
 171                         mbus = list_entry(p, struct mon_bus, bus_link);
 172                         /*
 173                          * We do not change nreaders here, so rely on mon_lock.
 174                          */
 175                         if (mbus->nreaders == 0 && (ubus = mbus->u_bus) != NULL)
 176                                 ubus->monitored = 0;
 177                 }
 178         } else {
 179                 /*
 180                  * A stop can be called for a dissolved mon_bus in case of
 181                  * a reader staying across an rmmod foo_hcd, so test ->u_bus.
 182                  */
 183                 if (mon_bus0.nreaders == 0 && (ubus = mbus->u_bus) != NULL) {
 184                         ubus->monitored = 0;
 185                         mb();
 186                 }
 187         }
 188 }
 189
 190 /*
 191  * Add a USB bus (usually by a modprobe foo-hcd)
 192  *
 193  * This does not return an error code because the core cannot care less
 194  * if monitoring is not established.
 195  */
 196 static void mon_bus_add(struct usb_bus *ubus)
 197 {
 198         mon_bus_init(ubus);
 199         mutex_lock(&mon_lock);
 200         if (mon_bus0.nreaders != 0)
 201                 ubus->monitored = 1;
 202         mutex_unlock(&mon_lock);
 203 }
 204
 205 /*
 206  * Remove a USB bus (either from rmmod foo-hcd or from a hot-remove event).
 207  */
 208 static void mon_bus_remove(struct usb_bus *ubus)
 209 {
 210         struct mon_bus *mbus = ubus->mon_bus;
 211
 212         mutex_lock(&mon_lock);
 213         list_del(&mbus->bus_link);
 214         if (mbus->text_inited)
 215                 mon_text_del(mbus);
 216         if (mbus->bin_inited)
 217                 mon_bin_del(mbus);
 218
 219         mon_dissolve(mbus, ubus);
 220         kref_put(&mbus->ref, mon_bus_drop);
 221         mutex_unlock(&mon_lock);
 222 }
 223
 224 static int mon_notify(struct notifier_block *self, unsigned long action,
 225                       void *dev)
 226 {
 227         switch (action) {
 228         case USB_BUS_ADD:
 229                 mon_bus_add(dev);
 230                 break;
 231         case USB_BUS_REMOVE:
 232                 mon_bus_remove(dev);
 233         }
 234         return NOTIFY_OK;
 235 }
 236
 237 static struct notifier_block mon_nb = {
 238         .notifier_call =        mon_notify,
 239 };
 240
 241 /*
 242  * Ops
 243  */
 244 static const struct usb_mon_operations mon_ops_0 = {
 245         .urb_submit =   mon_submit,
 246         .urb_submit_error = mon_submit_error,
 247         .urb_complete = mon_complete,
 248 };
 249
 250 /*
 251  * Tear usb_bus and mon_bus apart.
 252  */
 253 static void mon_dissolve(struct mon_bus *mbus, struct usb_bus *ubus)
 254 {
 255
 256         if (ubus->monitored) {
 257                 ubus->monitored = 0;
 258                 mb();
 259         }
 260
 261         ubus->mon_bus = NULL;
 262         mbus->u_bus = NULL;
 263         mb();
 264
 265         /* We want synchronize_irq() here, but that needs an argument. */
 266 }
 267
 268 /*
 269  */
 270 static void mon_bus_drop(struct kref *r)
 271 {
 272         struct mon_bus *mbus = container_of(r, struct mon_bus, ref);
 273         kfree(mbus);
 274 }
 275
 276 /*
 277  * Initialize a bus for us:
 278  *  - allocate mon_bus
 279  *  - refcount USB bus struct
 280  *  - link
 281  */
 282 static void mon_bus_init(struct usb_bus *ubus)
 283 {
 284         struct mon_bus *mbus;
 285
 286         mbus = kzalloc(sizeof(struct mon_bus), GFP_KERNEL);
 287         if (mbus == NULL)
 288                 goto err_alloc;
 289         kref_init(&mbus->ref);
 290         spin_lock_init(&mbus->lock);
 291         INIT_LIST_HEAD(&mbus->r_list);
 292
 293         /*
 294          * We don't need to take a reference to ubus, because we receive
 295          * a notification if the bus is about to be removed.
 296          */
 297         mbus->u_bus = ubus;
 298         ubus->mon_bus = mbus;
 299
 300         mbus->text_inited = mon_text_add(mbus, ubus);
 301         mbus->bin_inited = mon_bin_add(mbus, ubus);
 302
 303         mutex_lock(&mon_lock);
 304         list_add_tail(&mbus->bus_link, &mon_buses);
 305         mutex_unlock(&mon_lock);
 306         return;
 307
 308 err_alloc:
 309         return;
 310 }
 311
 312 static void mon_bus0_init(void)
 313 {
 314         struct mon_bus *mbus = &mon_bus0;
 315
 316         kref_init(&mbus->ref);
 317         spin_lock_init(&mbus->lock);
 318         INIT_LIST_HEAD(&mbus->r_list);
 319
 320         mbus->text_inited = mon_text_add(mbus, NULL);
 321         mbus->bin_inited = mon_bin_add(mbus, NULL);
 322 }
 323
 324 /*
 325  * Search a USB bus by number. Notice that USB bus numbers start from one,
 326  * which we may later use to identify "all" with zero.
 327  *
 328  * This function must be called with mon_lock held.
 329  *
 330  * This is obviously inefficient and may be revised in the future.
 331  */
 332 struct mon_bus *mon_bus_lookup(unsigned int num)
 333 {
 334         struct list_head *p;
 335         struct mon_bus *mbus;
 336
 337         if (num == 0) {
 338                 return &mon_bus0;
 339         }
 340         list_for_each (p, &mon_buses) {
 341                 mbus = list_entry(p, struct mon_bus, bus_link);
 342                 if (mbus->u_bus->busnum == num) {
 343                         return mbus;
 344                 }
 345         }
 346         return NULL;
 347 }
 348
 349 static int __init mon_init(void)
 350 {
 351         struct usb_bus *ubus;
 352         int rc, id;
 353
 354         if ((rc = mon_text_init()) != 0)
 355                 goto err_text;
 356         if ((rc = mon_bin_init()) != 0)
 357                 goto err_bin;
 358
 359         mon_bus0_init();
 360
 361         if (usb_mon_register(&mon_ops_0) != 0) {
 362                 printk(KERN_NOTICE TAG ": unable to register with the core\n");
 363                 rc = -ENODEV;
 364                 goto err_reg;
 365         }
 366         // MOD_INC_USE_COUNT(which_module?);
 367
 368         mutex_lock(&usb_bus_idr_lock);
 369         idr_for_each_entry(&usb_bus_idr, ubus, id)
 370                 mon_bus_init(ubus);
 371         usb_register_notify(&mon_nb);
 372         mutex_unlock(&usb_bus_idr_lock);
 373         return 0;
 374
 375 err_reg:
 376         mon_bin_exit();
 377 err_bin:
 378         mon_text_exit();
 379 err_text:
 380         return rc;
 381 }
 382
 383 static void __exit mon_exit(void)
 384 {
 385         struct mon_bus *mbus;
 386         struct list_head *p;
 387
 388         usb_unregister_notify(&mon_nb);
 389         usb_mon_deregister();
 390
 391         mutex_lock(&mon_lock);
 392
 393         while (!list_empty(&mon_buses)) {
 394                 p = mon_buses.next;
 395                 mbus = list_entry(p, struct mon_bus, bus_link);
 396                 list_del(p);
 397
 398                 if (mbus->text_inited)
 399                         mon_text_del(mbus);
 400                 if (mbus->bin_inited)
 401                         mon_bin_del(mbus);
 402
 403                 /*
 404                  * This never happens, because the open/close paths in
 405                  * file level maintain module use counters and so rmmod fails
 406                  * before reaching here. However, better be safe...
 407                  */
 408                 if (mbus->nreaders) {
 409                         printk(KERN_ERR TAG
 410                             ": Outstanding opens (%d) on usb%d, leaking...\n",
 411                             mbus->nreaders, mbus->u_bus->busnum);
 412                         atomic_set(&mbus->ref.refcount, 2);     /* Force leak */
 413                 }
 414
 415                 mon_dissolve(mbus, mbus->u_bus);
 416                 kref_put(&mbus->ref, mon_bus_drop);
 417         }
 418
 419         mbus = &mon_bus0;
 420         if (mbus->text_inited)
 421                 mon_text_del(mbus);
 422         if (mbus->bin_inited)
 423                 mon_bin_del(mbus);
 424
 425         mutex_unlock(&mon_lock);
 426
 427         mon_text_exit();
 428         mon_bin_exit();
 429 }
 430
 431 module_init(mon_init);
 432 module_exit(mon_exit);
 433
 434 MODULE_LICENSE("GPL");