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/slab.h>
  13 #include <linux/notifier.h>
  14 #include <linux/mutex.h>
  15
  16 #include "usb_mon.h"
  17 #include "../core/hcd.h"
  18
  19 static void mon_stop(struct mon_bus *mbus);
  20 static void mon_dissolve(struct mon_bus *mbus, struct usb_bus *ubus);
  21 static void mon_bus_drop(struct kref *r);
  22 static void mon_bus_init(struct usb_bus *ubus);
  23
  24 DEFINE_MUTEX(mon_lock);
  25
  26 struct mon_bus mon_bus0;                /* Pseudo bus meaning "all buses" */
  27 static LIST_HEAD(mon_buses);            /* All buses we know: struct mon_bus */
  28
  29 /*
  30  * Link a reader into the bus.
  31  *
  32  * This must be called with mon_lock taken because of mbus->ref.
  33  */
  34 void mon_reader_add(struct mon_bus *mbus, struct mon_reader *r)
  35 {
  36         unsigned long flags;
  37         struct list_head *p;
  38
  39         spin_lock_irqsave(&mbus->lock, flags);
  40         if (mbus->nreaders == 0) {
  41                 if (mbus == &mon_bus0) {
  42                         list_for_each (p, &mon_buses) {
  43                                 struct mon_bus *m1;
  44                                 m1 = list_entry(p, struct mon_bus, bus_link);
  45                                 m1->u_bus->monitored = 1;
  46                         }
  47                 } else {
  48                         mbus->u_bus->monitored = 1;
  49                 }
  50         }
  51         mbus->nreaders++;
  52         list_add_tail(&r->r_link, &mbus->r_list);
  53         spin_unlock_irqrestore(&mbus->lock, flags);
  54
  55         kref_get(&mbus->ref);
  56 }
  57
  58 /*
  59  * Unlink reader from the bus.
  60  *
  61  * This is called with mon_lock taken, so we can decrement mbus->ref.
  62  */
  63 void mon_reader_del(struct mon_bus *mbus, struct mon_reader *r)
  64 {
  65         unsigned long flags;
  66
  67         spin_lock_irqsave(&mbus->lock, flags);
  68         list_del(&r->r_link);
  69         --mbus->nreaders;
  70         if (mbus->nreaders == 0)
  71                 mon_stop(mbus);
  72         spin_unlock_irqrestore(&mbus->lock, flags);
  73
  74         kref_put(&mbus->ref, mon_bus_drop);
  75 }
  76
  77 /*
  78  */
  79 static void mon_bus_submit(struct mon_bus *mbus, struct urb *urb)
  80 {
  81         unsigned long flags;
  82         struct list_head *pos;
  83         struct mon_reader *r;
  84
  85         spin_lock_irqsave(&mbus->lock, flags);
  86         mbus->cnt_events++;
  87         list_for_each (pos, &mbus->r_list) {
  88                 r = list_entry(pos, struct mon_reader, r_link);
  89                 r->rnf_submit(r->r_data, urb);
  90         }
  91         spin_unlock_irqrestore(&mbus->lock, flags);
  92         return;
  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         return;
 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         if ((mbus = ubus->mon_bus) != NULL)
 127                 mon_bus_submit_error(mbus, urb, error);
 128         mon_bus_submit_error(&mon_bus0, urb, error);
 129 }
 130
 131 /*
 132  */
 133 static void mon_bus_complete(struct mon_bus *mbus, struct urb *urb, 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         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");