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         if ((mbus = ubus->mon_bus) != NULL)
 100                 mon_bus_submit(mbus, urb);
 101         mon_bus_submit(&mon_bus0, urb);
 102 }
 103
 104 /*
 105  */
 106 static 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
 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         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
 372 err_reg:
 373         mon_bin_exit();
 374 err_bin:
 375         mon_text_exit();
 376 err_text:
 377         return rc;
 378 }
 379
 380 static 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
 428 module_init(mon_init);
 429 module_exit(mon_exit);
 430
 431 MODULE_LICENSE("GPL");