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/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)
 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);
 143         }
 144         spin_unlock_irqrestore(&mbus->lock, flags);
 145 }
 146
 147 static void mon_complete(struct usb_bus *ubus, struct urb *urb)
 148 {
 149         struct mon_bus *mbus;
 150
 151         mbus = ubus->mon_bus;
 152         if (mbus == NULL) {
 153                 /*
 154                  * This should not happen.
 155                  * At this point we do not even know the bus number...
 156                  */
 157                 printk(KERN_ERR TAG ": Null mon bus in URB, pipe 0x%x\n",
 158                     urb->pipe);
 159                 return;
 160         }
 161
 162         mon_bus_complete(mbus, urb);
 163         mon_bus_complete(&mon_bus0, urb);
 164 }
 165
 166 /* int (*unlink_urb) (struct urb *urb, int status); */
 167
 168 /*
 169  * Stop monitoring.
 170  */
 171 static void mon_stop(struct mon_bus *mbus)
 172 {
 173         struct usb_bus *ubus = mbus->u_bus;
 174         struct list_head *p;
 175
 176         if (mbus == &mon_bus0) {
 177                 list_for_each (p, &mon_buses) {
 178                         mbus = list_entry(p, struct mon_bus, bus_link);
 179                         /*
 180                          * We do not change nreaders here, so rely on mon_lock.
 181                          */
 182                         if (mbus->nreaders == 0 && (ubus = mbus->u_bus) != NULL)
 183                                 ubus->monitored = 0;
 184                 }
 185         } else {
 186                 /*
 187                  * A stop can be called for a dissolved mon_bus in case of
 188                  * a reader staying across an rmmod foo_hcd, so test ->u_bus.
 189                  */
 190                 if (mon_bus0.nreaders == 0 && (ubus = mbus->u_bus) != NULL) {
 191                         ubus->monitored = 0;
 192                         mb();
 193                 }
 194         }
 195 }
 196
 197 /*
 198  * Add a USB bus (usually by a modprobe foo-hcd)
 199  *
 200  * This does not return an error code because the core cannot care less
 201  * if monitoring is not established.
 202  */
 203 static void mon_bus_add(struct usb_bus *ubus)
 204 {
 205         mon_bus_init(ubus);
 206         mutex_lock(&mon_lock);
 207         if (mon_bus0.nreaders != 0)
 208                 ubus->monitored = 1;
 209         mutex_unlock(&mon_lock);
 210 }
 211
 212 /*
 213  * Remove a USB bus (either from rmmod foo-hcd or from a hot-remove event).
 214  */
 215 static void mon_bus_remove(struct usb_bus *ubus)
 216 {
 217         struct mon_bus *mbus = ubus->mon_bus;
 218
 219         mutex_lock(&mon_lock);
 220         list_del(&mbus->bus_link);
 221         if (mbus->text_inited)
 222                 mon_text_del(mbus);
 223
 224         mon_dissolve(mbus, ubus);
 225         kref_put(&mbus->ref, mon_bus_drop);
 226         mutex_unlock(&mon_lock);
 227 }
 228
 229 static int mon_notify(struct notifier_block *self, unsigned long action,
 230                       void *dev)
 231 {
 232         switch (action) {
 233         case USB_BUS_ADD:
 234                 mon_bus_add(dev);
 235                 break;
 236         case USB_BUS_REMOVE:
 237                 mon_bus_remove(dev);
 238         }
 239         return NOTIFY_OK;
 240 }
 241
 242 static struct notifier_block mon_nb = {
 243         .notifier_call =        mon_notify,
 244 };
 245
 246 /*
 247  * Ops
 248  */
 249 static struct usb_mon_operations mon_ops_0 = {
 250         .urb_submit =   mon_submit,
 251         .urb_submit_error = mon_submit_error,
 252         .urb_complete = mon_complete,
 253 };
 254
 255 /*
 256  * Tear usb_bus and mon_bus apart.
 257  */
 258 static void mon_dissolve(struct mon_bus *mbus, struct usb_bus *ubus)
 259 {
 260
 261         if (ubus->monitored) {
 262                 ubus->monitored = 0;
 263                 mb();
 264         }
 265
 266         ubus->mon_bus = NULL;
 267         mbus->u_bus = NULL;
 268         mb();
 269
 270         /* We want synchronize_irq() here, but that needs an argument. */
 271 }
 272
 273 /*
 274  */
 275 static void mon_bus_drop(struct kref *r)
 276 {
 277         struct mon_bus *mbus = container_of(r, struct mon_bus, ref);
 278         kfree(mbus);
 279 }
 280
 281 /*
 282  * Initialize a bus for us:
 283  *  - allocate mon_bus
 284  *  - refcount USB bus struct
 285  *  - link
 286  */
 287 static void mon_bus_init(struct usb_bus *ubus)
 288 {
 289         struct mon_bus *mbus;
 290
 291         if ((mbus = kzalloc(sizeof(struct mon_bus), GFP_KERNEL)) == NULL)
 292                 goto err_alloc;
 293         kref_init(&mbus->ref);
 294         spin_lock_init(&mbus->lock);
 295         INIT_LIST_HEAD(&mbus->r_list);
 296
 297         /*
 298          * We don't need to take a reference to ubus, because we receive
 299          * a notification if the bus is about to be removed.
 300          */
 301         mbus->u_bus = ubus;
 302         ubus->mon_bus = mbus;
 303
 304         mbus->text_inited = mon_text_add(mbus, ubus->busnum);
 305         // mon_bin_add(...)
 306
 307         mutex_lock(&mon_lock);
 308         list_add_tail(&mbus->bus_link, &mon_buses);
 309         mutex_unlock(&mon_lock);
 310         return;
 311
 312 err_alloc:
 313         return;
 314 }
 315
 316 static void mon_bus0_init(void)
 317 {
 318         struct mon_bus *mbus = &mon_bus0;
 319
 320         kref_init(&mbus->ref);
 321         spin_lock_init(&mbus->lock);
 322         INIT_LIST_HEAD(&mbus->r_list);
 323
 324         mbus->text_inited = mon_text_add(mbus, 0);
 325         // mbus->bin_inited = mon_bin_add(mbus, 0);
 326 }
 327
 328 /*
 329  * Search a USB bus by number. Notice that USB bus numbers start from one,
 330  * which we may later use to identify "all" with zero.
 331  *
 332  * This function must be called with mon_lock held.
 333  *
 334  * This is obviously inefficient and may be revised in the future.
 335  */
 336 struct mon_bus *mon_bus_lookup(unsigned int num)
 337 {
 338         struct list_head *p;
 339         struct mon_bus *mbus;
 340
 341         if (num == 0) {
 342                 return &mon_bus0;
 343         }
 344         list_for_each (p, &mon_buses) {
 345                 mbus = list_entry(p, struct mon_bus, bus_link);
 346                 if (mbus->u_bus->busnum == num) {
 347                         return mbus;
 348                 }
 349         }
 350         return NULL;
 351 }
 352
 353 static int __init mon_init(void)
 354 {
 355         struct usb_bus *ubus;
 356         int rc;
 357
 358         if ((rc = mon_text_init()) != 0)
 359                 goto err_text;
 360         if ((rc = mon_bin_init()) != 0)
 361                 goto err_bin;
 362
 363         mon_bus0_init();
 364
 365         if (usb_mon_register(&mon_ops_0) != 0) {
 366                 printk(KERN_NOTICE TAG ": unable to register with the core\n");
 367                 rc = -ENODEV;
 368                 goto err_reg;
 369         }
 370         // MOD_INC_USE_COUNT(which_module?);
 371
 372         usb_register_notify(&mon_nb);
 373
 374         mutex_lock(&usb_bus_list_lock);
 375         list_for_each_entry (ubus, &usb_bus_list, bus_list) {
 376                 mon_bus_init(ubus);
 377         }
 378         mutex_unlock(&usb_bus_list_lock);
 379         return 0;
 380
 381 err_reg:
 382         mon_bin_exit();
 383 err_bin:
 384         mon_text_exit();
 385 err_text:
 386         return rc;
 387 }
 388
 389 static void __exit mon_exit(void)
 390 {
 391         struct mon_bus *mbus;
 392         struct list_head *p;
 393
 394         usb_unregister_notify(&mon_nb);
 395         usb_mon_deregister();
 396
 397         mutex_lock(&mon_lock);
 398
 399         while (!list_empty(&mon_buses)) {
 400                 p = mon_buses.next;
 401                 mbus = list_entry(p, struct mon_bus, bus_link);
 402                 list_del(p);
 403
 404                 if (mbus->text_inited)
 405                         mon_text_del(mbus);
 406
 407                 /*
 408                  * This never happens, because the open/close paths in
 409                  * file level maintain module use counters and so rmmod fails
 410                  * before reaching here. However, better be safe...
 411                  */
 412                 if (mbus->nreaders) {
 413                         printk(KERN_ERR TAG
 414                             ": Outstanding opens (%d) on usb%d, leaking...\n",
 415                             mbus->nreaders, mbus->u_bus->busnum);
 416                         atomic_set(&mbus->ref.refcount, 2);     /* Force leak */
 417                 }
 418
 419                 mon_dissolve(mbus, mbus->u_bus);
 420                 kref_put(&mbus->ref, mon_bus_drop);
 421         }
 422
 423         mbus = &mon_bus0;
 424         if (mbus->text_inited)
 425                 mon_text_del(mbus);
 426
 427         mutex_unlock(&mon_lock);
 428
 429         mon_text_exit();
 430         mon_bin_exit();
 431 }
 432
 433 module_init(mon_init);
 434 module_exit(mon_exit);
 435
 436 MODULE_LICENSE("GPL");