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         return;
  94 }
  95
  96 static void mon_submit(struct usb_bus *ubus, struct urb *urb)
  97 {
  98         struct mon_bus *mbus;
  99
 100         if ((mbus = ubus->mon_bus) != 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         return;
 121 }
 122
 123 static void mon_submit_error(struct usb_bus *ubus, struct urb *urb, int error)
 124 {
 125         struct mon_bus *mbus;
 126
 127         if ((mbus = ubus->mon_bus) != 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         if ((mbus = ubus->mon_bus) != NULL)
 154                 mon_bus_complete(mbus, urb, status);
 155         mon_bus_complete(&mon_bus0, urb, status);
 156 }
 157
 158 /* int (*unlink_urb) (struct urb *urb, int status); */
 159
 160 /*
 161  * Stop monitoring.
 162  */
 163 static void mon_stop(struct mon_bus *mbus)
 164 {
 165         struct usb_bus *ubus;
 166         struct list_head *p;
 167
 168         if (mbus == &mon_bus0) {
 169                 list_for_each (p, &mon_buses) {
 170                         mbus = list_entry(p, struct mon_bus, bus_link);
 171                         /*
 172                          * We do not change nreaders here, so rely on mon_lock.
 173                          */
 174                         if (mbus->nreaders == 0 && (ubus = mbus->u_bus) != NULL)
 175                                 ubus->monitored = 0;
 176                 }
 177         } else {
 178                 /*
 179                  * A stop can be called for a dissolved mon_bus in case of
 180                  * a reader staying across an rmmod foo_hcd, so test ->u_bus.
 181                  */
 182                 if (mon_bus0.nreaders == 0 && (ubus = mbus->u_bus) != NULL) {
 183                         ubus->monitored = 0;
 184                         mb();
 185                 }
 186         }
 187 }
 188
 189 /*
 190  * Add a USB bus (usually by a modprobe foo-hcd)
 191  *
 192  * This does not return an error code because the core cannot care less
 193  * if monitoring is not established.
 194  */
 195 static void mon_bus_add(struct usb_bus *ubus)
 196 {
 197         mon_bus_init(ubus);
 198         mutex_lock(&mon_lock);
 199         if (mon_bus0.nreaders != 0)
 200                 ubus->monitored = 1;
 201         mutex_unlock(&mon_lock);
 202 }
 203
 204 /*
 205  * Remove a USB bus (either from rmmod foo-hcd or from a hot-remove event).
 206  */
 207 static void mon_bus_remove(struct usb_bus *ubus)
 208 {
 209         struct mon_bus *mbus = ubus->mon_bus;
 210
 211         mutex_lock(&mon_lock);
 212         list_del(&mbus->bus_link);
 213         if (mbus->text_inited)
 214                 mon_text_del(mbus);
 215         if (mbus->bin_inited)
 216                 mon_bin_del(mbus);
 217
 218         mon_dissolve(mbus, ubus);
 219         kref_put(&mbus->ref, mon_bus_drop);
 220         mutex_unlock(&mon_lock);
 221 }
 222
 223 static int mon_notify(struct notifier_block *self, unsigned long action,
 224                       void *dev)
 225 {
 226         switch (action) {
 227         case USB_BUS_ADD:
 228                 mon_bus_add(dev);
 229                 break;
 230         case USB_BUS_REMOVE:
 231                 mon_bus_remove(dev);
 232         }
 233         return NOTIFY_OK;
 234 }
 235
 236 static struct notifier_block mon_nb = {
 237         .notifier_call =        mon_notify,
 238 };
 239
 240 /*
 241  * Ops
 242  */
 243 static struct usb_mon_operations mon_ops_0 = {
 244         .urb_submit =   mon_submit,
 245         .urb_submit_error = mon_submit_error,
 246         .urb_complete = mon_complete,
 247 };
 248
 249 /*
 250  * Tear usb_bus and mon_bus apart.
 251  */
 252 static void mon_dissolve(struct mon_bus *mbus, struct usb_bus *ubus)
 253 {
 254
 255         if (ubus->monitored) {
 256                 ubus->monitored = 0;
 257                 mb();
 258         }
 259
 260         ubus->mon_bus = NULL;
 261         mbus->u_bus = NULL;
 262         mb();
 263
 264         /* We want synchronize_irq() here, but that needs an argument. */
 265 }
 266
 267 /*
 268  */
 269 static void mon_bus_drop(struct kref *r)
 270 {
 271         struct mon_bus *mbus = container_of(r, struct mon_bus, ref);
 272         kfree(mbus);
 273 }
 274
 275 /*
 276  * Initialize a bus for us:
 277  *  - allocate mon_bus
 278  *  - refcount USB bus struct
 279  *  - link
 280  */
 281 static void mon_bus_init(struct usb_bus *ubus)
 282 {
 283         struct mon_bus *mbus;
 284
 285         if ((mbus = kzalloc(sizeof(struct mon_bus), GFP_KERNEL)) == NULL)
 286                 goto err_alloc;
 287         kref_init(&mbus->ref);
 288         spin_lock_init(&mbus->lock);
 289         INIT_LIST_HEAD(&mbus->r_list);
 290
 291         /*
 292          * We don't need to take a reference to ubus, because we receive
 293          * a notification if the bus is about to be removed.
 294          */
 295         mbus->u_bus = ubus;
 296         ubus->mon_bus = mbus;
 297
 298         mbus->text_inited = mon_text_add(mbus, ubus);
 299         mbus->bin_inited = mon_bin_add(mbus, ubus);
 300
 301         mutex_lock(&mon_lock);
 302         list_add_tail(&mbus->bus_link, &mon_buses);
 303         mutex_unlock(&mon_lock);
 304         return;
 305
 306 err_alloc:
 307         return;
 308 }
 309
 310 static void mon_bus0_init(void)
 311 {
 312         struct mon_bus *mbus = &mon_bus0;
 313
 314         kref_init(&mbus->ref);
 315         spin_lock_init(&mbus->lock);
 316         INIT_LIST_HEAD(&mbus->r_list);
 317
 318         mbus->text_inited = mon_text_add(mbus, NULL);
 319         mbus->bin_inited = mon_bin_add(mbus, NULL);
 320 }
 321
 322 /*
 323  * Search a USB bus by number. Notice that USB bus numbers start from one,
 324  * which we may later use to identify "all" with zero.
 325  *
 326  * This function must be called with mon_lock held.
 327  *
 328  * This is obviously inefficient and may be revised in the future.
 329  */
 330 struct mon_bus *mon_bus_lookup(unsigned int num)
 331 {
 332         struct list_head *p;
 333         struct mon_bus *mbus;
 334
 335         if (num == 0) {
 336                 return &mon_bus0;
 337         }
 338         list_for_each (p, &mon_buses) {
 339                 mbus = list_entry(p, struct mon_bus, bus_link);
 340                 if (mbus->u_bus->busnum == num) {
 341                         return mbus;
 342                 }
 343         }
 344         return NULL;
 345 }
 346
 347 static int __init mon_init(void)
 348 {
 349         struct usb_bus *ubus;
 350         int rc;
 351
 352         if ((rc = mon_text_init()) != 0)
 353                 goto err_text;
 354         if ((rc = mon_bin_init()) != 0)
 355                 goto err_bin;
 356
 357         mon_bus0_init();
 358
 359         if (usb_mon_register(&mon_ops_0) != 0) {
 360                 printk(KERN_NOTICE TAG ": unable to register with the core\n");
 361                 rc = -ENODEV;
 362                 goto err_reg;
 363         }
 364         // MOD_INC_USE_COUNT(which_module?);
 365
 366         mutex_lock(&usb_bus_list_lock);
 367         list_for_each_entry (ubus, &usb_bus_list, bus_list) {
 368                 mon_bus_init(ubus);
 369         }
 370         usb_register_notify(&mon_nb);
 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");