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         if (mbus->bin_inited)
 224                 mon_bin_del(mbus);
 225
 226         mon_dissolve(mbus, ubus);
 227         kref_put(&mbus->ref, mon_bus_drop);
 228         mutex_unlock(&mon_lock);
 229 }
 230
 231 static int mon_notify(struct notifier_block *self, unsigned long action,
 232                       void *dev)
 233 {
 234         switch (action) {
 235         case USB_BUS_ADD:
 236                 mon_bus_add(dev);
 237                 break;
 238         case USB_BUS_REMOVE:
 239                 mon_bus_remove(dev);
 240         }
 241         return NOTIFY_OK;
 242 }
 243
 244 static struct notifier_block mon_nb = {
 245         .notifier_call =        mon_notify,
 246 };
 247
 248 /*
 249  * Ops
 250  */
 251 static struct usb_mon_operations mon_ops_0 = {
 252         .urb_submit =   mon_submit,
 253         .urb_submit_error = mon_submit_error,
 254         .urb_complete = mon_complete,
 255 };
 256
 257 /*
 258  * Tear usb_bus and mon_bus apart.
 259  */
 260 static void mon_dissolve(struct mon_bus *mbus, struct usb_bus *ubus)
 261 {
 262
 263         if (ubus->monitored) {
 264                 ubus->monitored = 0;
 265                 mb();
 266         }
 267
 268         ubus->mon_bus = NULL;
 269         mbus->u_bus = NULL;
 270         mb();
 271
 272         /* We want synchronize_irq() here, but that needs an argument. */
 273 }
 274
 275 /*
 276  */
 277 static void mon_bus_drop(struct kref *r)
 278 {
 279         struct mon_bus *mbus = container_of(r, struct mon_bus, ref);
 280         kfree(mbus);
 281 }
 282
 283 /*
 284  * Initialize a bus for us:
 285  *  - allocate mon_bus
 286  *  - refcount USB bus struct
 287  *  - link
 288  */
 289 static void mon_bus_init(struct usb_bus *ubus)
 290 {
 291         struct mon_bus *mbus;
 292
 293         if ((mbus = kzalloc(sizeof(struct mon_bus), GFP_KERNEL)) == NULL)
 294                 goto err_alloc;
 295         kref_init(&mbus->ref);
 296         spin_lock_init(&mbus->lock);
 297         INIT_LIST_HEAD(&mbus->r_list);
 298
 299         /*
 300          * We don't need to take a reference to ubus, because we receive
 301          * a notification if the bus is about to be removed.
 302          */
 303         mbus->u_bus = ubus;
 304         ubus->mon_bus = mbus;
 305
 306         mbus->text_inited = mon_text_add(mbus, ubus);
 307         mbus->bin_inited = mon_bin_add(mbus, ubus);
 308
 309         mutex_lock(&mon_lock);
 310         list_add_tail(&mbus->bus_link, &mon_buses);
 311         mutex_unlock(&mon_lock);
 312         return;
 313
 314 err_alloc:
 315         return;
 316 }
 317
 318 static void mon_bus0_init(void)
 319 {
 320         struct mon_bus *mbus = &mon_bus0;
 321
 322         kref_init(&mbus->ref);
 323         spin_lock_init(&mbus->lock);
 324         INIT_LIST_HEAD(&mbus->r_list);
 325
 326         mbus->text_inited = mon_text_add(mbus, NULL);
 327         mbus->bin_inited = mon_bin_add(mbus, NULL);
 328 }
 329
 330 /*
 331  * Search a USB bus by number. Notice that USB bus numbers start from one,
 332  * which we may later use to identify "all" with zero.
 333  *
 334  * This function must be called with mon_lock held.
 335  *
 336  * This is obviously inefficient and may be revised in the future.
 337  */
 338 struct mon_bus *mon_bus_lookup(unsigned int num)
 339 {
 340         struct list_head *p;
 341         struct mon_bus *mbus;
 342
 343         if (num == 0) {
 344                 return &mon_bus0;
 345         }
 346         list_for_each (p, &mon_buses) {
 347                 mbus = list_entry(p, struct mon_bus, bus_link);
 348                 if (mbus->u_bus->busnum == num) {
 349                         return mbus;
 350                 }
 351         }
 352         return NULL;
 353 }
 354
 355 static int __init mon_init(void)
 356 {
 357         struct usb_bus *ubus;
 358         int rc;
 359
 360         if ((rc = mon_text_init()) != 0)
 361                 goto err_text;
 362         if ((rc = mon_bin_init()) != 0)
 363                 goto err_bin;
 364
 365         mon_bus0_init();
 366
 367         if (usb_mon_register(&mon_ops_0) != 0) {
 368                 printk(KERN_NOTICE TAG ": unable to register with the core\n");
 369                 rc = -ENODEV;
 370                 goto err_reg;
 371         }
 372         // MOD_INC_USE_COUNT(which_module?);
 373
 374         usb_register_notify(&mon_nb);
 375
 376         mutex_lock(&usb_bus_list_lock);
 377         list_for_each_entry (ubus, &usb_bus_list, bus_list) {
 378                 mon_bus_init(ubus);
 379         }
 380         mutex_unlock(&usb_bus_list_lock);
 381         return 0;
 382
 383 err_reg:
 384         mon_bin_exit();
 385 err_bin:
 386         mon_text_exit();
 387 err_text:
 388         return rc;
 389 }
 390
 391 static void __exit mon_exit(void)
 392 {
 393         struct mon_bus *mbus;
 394         struct list_head *p;
 395
 396         usb_unregister_notify(&mon_nb);
 397         usb_mon_deregister();
 398
 399         mutex_lock(&mon_lock);
 400
 401         while (!list_empty(&mon_buses)) {
 402                 p = mon_buses.next;
 403                 mbus = list_entry(p, struct mon_bus, bus_link);
 404                 list_del(p);
 405
 406                 if (mbus->text_inited)
 407                         mon_text_del(mbus);
 408                 if (mbus->bin_inited)
 409                         mon_bin_del(mbus);
 410
 411                 /*
 412                  * This never happens, because the open/close paths in
 413                  * file level maintain module use counters and so rmmod fails
 414                  * before reaching here. However, better be safe...
 415                  */
 416                 if (mbus->nreaders) {
 417                         printk(KERN_ERR TAG
 418                             ": Outstanding opens (%d) on usb%d, leaking...\n",
 419                             mbus->nreaders, mbus->u_bus->busnum);
 420                         atomic_set(&mbus->ref.refcount, 2);     /* Force leak */
 421                 }
 422
 423                 mon_dissolve(mbus, mbus->u_bus);
 424                 kref_put(&mbus->ref, mon_bus_drop);
 425         }
 426
 427         mbus = &mon_bus0;
 428         if (mbus->text_inited)
 429                 mon_text_del(mbus);
 430         if (mbus->bin_inited)
 431                 mon_bin_del(mbus);
 432
 433         mutex_unlock(&mon_lock);
 434
 435         mon_text_exit();
 436         mon_bin_exit();
 437 }
 438
 439 module_init(mon_init);
 440 module_exit(mon_exit);
 441
 442 MODULE_LICENSE("GPL");