drivers/usb/mon/mon_text.c

   1 /*
   2  * The USB Monitor, inspired by Dave Harding's USBMon.
   3  *
   4  * This is a text format reader.
   5  */
   6
   7 #include <linux/kernel.h>
   8 #include <linux/list.h>
   9 #include <linux/usb.h>
  10 #include <linux/slab.h>
  11 #include <linux/time.h>
  12 #include <linux/ktime.h>
  13 #include <linux/export.h>
  14 #include <linux/mutex.h>
  15 #include <linux/debugfs.h>
  16 #include <linux/scatterlist.h>
  17 #include <linux/uaccess.h>
  18
  19 #include "usb_mon.h"
  20
  21 /*
  22  * No, we do not want arbitrarily long data strings.
  23  * Use the binary interface if you want to capture bulk data!
  24  */
  25 #define DATA_MAX  32
  26
  27 /*
  28  * Defined by USB 2.0 clause 9.3, table 9.2.
  29  */
  30 #define SETUP_MAX  8
  31
  32 /*
  33  * This limit exists to prevent OOMs when the user process stops reading.
  34  * If usbmon were available to unprivileged processes, it might be open
  35  * to a local DoS. But we have to keep to root in order to prevent
  36  * password sniffing from HID devices.
  37  */
  38 #define EVENT_MAX  (4*PAGE_SIZE / sizeof(struct mon_event_text))
  39
  40 /*
  41  * Potentially unlimited number; we limit it for similar allocations.
  42  * The usbfs limits this to 128, but we're not quite as generous.
  43  */
  44 #define ISODESC_MAX   5
  45
  46 #define PRINTF_DFL  250   /* with 5 ISOs segs */
  47
  48 struct mon_iso_desc {
  49         int status;
  50         unsigned int offset;
  51         unsigned int length;    /* Unsigned here, signed in URB. Historic. */
  52 };
  53
  54 struct mon_event_text {
  55         struct list_head e_link;
  56         int type;               /* submit, complete, etc. */
  57         unsigned long id;       /* From pointer, most of the time */
  58         unsigned int tstamp;
  59         int busnum;
  60         char devnum;
  61         char epnum;
  62         char is_in;
  63         char xfertype;
  64         int length;             /* Depends on type: xfer length or act length */
  65         int status;
  66         int interval;
  67         int start_frame;
  68         int error_count;
  69         char setup_flag;
  70         char data_flag;
  71         int numdesc;            /* Full number */
  72         struct mon_iso_desc isodesc[ISODESC_MAX];
  73         unsigned char setup[SETUP_MAX];
  74         unsigned char data[DATA_MAX];
  75 };
  76
  77 #define SLAB_NAME_SZ  30
  78 struct mon_reader_text {
  79         struct kmem_cache *e_slab;
  80         int nevents;
  81         struct list_head e_list;
  82         struct mon_reader r;    /* In C, parent class can be placed anywhere */
  83
  84         wait_queue_head_t wait;
  85         int printf_size;
  86         char *printf_buf;
  87         struct mutex printf_lock;
  88
  89         char slab_name[SLAB_NAME_SZ];
  90 };
  91
  92 static struct dentry *mon_dir;          /* Usually /sys/kernel/debug/usbmon */
  93
  94 static void mon_text_ctor(void *);
  95
  96 struct mon_text_ptr {
  97         int cnt, limit;
  98         char *pbuf;
  99 };
 100
 101 static struct mon_event_text *
 102     mon_text_read_wait(struct mon_reader_text *rp, struct file *file);
 103 static void mon_text_read_head_t(struct mon_reader_text *rp,
 104         struct mon_text_ptr *p, const struct mon_event_text *ep);
 105 static void mon_text_read_head_u(struct mon_reader_text *rp,
 106         struct mon_text_ptr *p, const struct mon_event_text *ep);
 107 static void mon_text_read_statset(struct mon_reader_text *rp,
 108         struct mon_text_ptr *p, const struct mon_event_text *ep);
 109 static void mon_text_read_intstat(struct mon_reader_text *rp,
 110         struct mon_text_ptr *p, const struct mon_event_text *ep);
 111 static void mon_text_read_isostat(struct mon_reader_text *rp,
 112         struct mon_text_ptr *p, const struct mon_event_text *ep);
 113 static void mon_text_read_isodesc(struct mon_reader_text *rp,
 114         struct mon_text_ptr *p, const struct mon_event_text *ep);
 115 static void mon_text_read_data(struct mon_reader_text *rp,
 116     struct mon_text_ptr *p, const struct mon_event_text *ep);
 117
 118 /*
 119  * mon_text_submit
 120  * mon_text_complete
 121  *
 122  * May be called from an interrupt.
 123  *
 124  * This is called with the whole mon_bus locked, so no additional lock.
 125  */
 126
 127 static inline char mon_text_get_setup(struct mon_event_text *ep,
 128     struct urb *urb, char ev_type, struct mon_bus *mbus)
 129 {
 130
 131         if (ep->xfertype != USB_ENDPOINT_XFER_CONTROL || ev_type != 'S')
 132                 return '-';
 133
 134         if (urb->setup_packet == NULL)
 135                 return 'Z';     /* '0' would be not as pretty. */
 136
 137         memcpy(ep->setup, urb->setup_packet, SETUP_MAX);
 138         return 0;
 139 }
 140
 141 static inline char mon_text_get_data(struct mon_event_text *ep, struct urb *urb,
 142     int len, char ev_type, struct mon_bus *mbus)
 143 {
 144         void *src;
 145
 146         if (len <= 0)
 147                 return 'L';
 148         if (len >= DATA_MAX)
 149                 len = DATA_MAX;
 150
 151         if (ep->is_in) {
 152                 if (ev_type != 'C')
 153                         return '<';
 154         } else {
 155                 if (ev_type != 'S')
 156                         return '>';
 157         }
 158
 159         if (urb->num_sgs == 0) {
 160                 src = urb->transfer_buffer;
 161                 if (src == NULL)
 162                         return 'Z';     /* '0' would be not as pretty. */
 163         } else {
 164                 struct scatterlist *sg = urb->sg;
 165
 166                 if (PageHighMem(sg_page(sg)))
 167                         return 'D';
 168
 169                 /* For the text interface we copy only the first sg buffer */
 170                 len = min_t(int, sg->length, len);
 171                 src = sg_virt(sg);
 172         }
 173
 174         memcpy(ep->data, src, len);
 175         return 0;
 176 }
 177
 178 static inline unsigned int mon_get_timestamp(void)
 179 {
 180         struct timespec64 now;
 181         unsigned int stamp;
 182
 183         ktime_get_ts64(&now);
 184         stamp = now.tv_sec & 0xFFF;  /* 2^32 = 4294967296. Limit to 4096s. */
 185         stamp = stamp * USEC_PER_SEC + now.tv_nsec / NSEC_PER_USEC;
 186         return stamp;
 187 }
 188
 189 static void mon_text_event(struct mon_reader_text *rp, struct urb *urb,
 190     char ev_type, int status)
 191 {
 192         struct mon_event_text *ep;
 193         unsigned int stamp;
 194         struct usb_iso_packet_descriptor *fp;
 195         struct mon_iso_desc *dp;
 196         int i, ndesc;
 197
 198         stamp = mon_get_timestamp();
 199
 200         if (rp->nevents >= EVENT_MAX ||
 201             (ep = kmem_cache_alloc(rp->e_slab, GFP_ATOMIC)) == NULL) {
 202                 rp->r.m_bus->cnt_text_lost++;
 203                 return;
 204         }
 205
 206         ep->type = ev_type;
 207         ep->id = (unsigned long) urb;
 208         ep->busnum = urb->dev->bus->busnum;
 209         ep->devnum = urb->dev->devnum;
 210         ep->epnum = usb_endpoint_num(&urb->ep->desc);
 211         ep->xfertype = usb_endpoint_type(&urb->ep->desc);
 212         ep->is_in = usb_urb_dir_in(urb);
 213         ep->tstamp = stamp;
 214         ep->length = (ev_type == 'S') ?
 215             urb->transfer_buffer_length : urb->actual_length;
 216         /* Collecting status makes debugging sense for submits, too */
 217         ep->status = status;
 218
 219         if (ep->xfertype == USB_ENDPOINT_XFER_INT) {
 220                 ep->interval = urb->interval;
 221         } else if (ep->xfertype == USB_ENDPOINT_XFER_ISOC) {
 222                 ep->interval = urb->interval;
 223                 ep->start_frame = urb->start_frame;
 224                 ep->error_count = urb->error_count;
 225         }
 226         ep->numdesc = urb->number_of_packets;
 227         if (ep->xfertype == USB_ENDPOINT_XFER_ISOC &&
 228                         urb->number_of_packets > 0) {
 229                 if ((ndesc = urb->number_of_packets) > ISODESC_MAX)
 230                         ndesc = ISODESC_MAX;
 231                 fp = urb->iso_frame_desc;
 232                 dp = ep->isodesc;
 233                 for (i = 0; i < ndesc; i++) {
 234                         dp->status = fp->status;
 235                         dp->offset = fp->offset;
 236                         dp->length = (ev_type == 'S') ?
 237                             fp->length : fp->actual_length;
 238                         fp++;
 239                         dp++;
 240                 }
 241                 /* Wasteful, but simple to understand: ISO 'C' is sparse. */
 242                 if (ev_type == 'C')
 243                         ep->length = urb->transfer_buffer_length;
 244         }
 245
 246         ep->setup_flag = mon_text_get_setup(ep, urb, ev_type, rp->r.m_bus);
 247         ep->data_flag = mon_text_get_data(ep, urb, ep->length, ev_type,
 248                         rp->r.m_bus);
 249
 250         rp->nevents++;
 251         list_add_tail(&ep->e_link, &rp->e_list);
 252         wake_up(&rp->wait);
 253 }
 254
 255 static void mon_text_submit(void *data, struct urb *urb)
 256 {
 257         struct mon_reader_text *rp = data;
 258         mon_text_event(rp, urb, 'S', -EINPROGRESS);
 259 }
 260
 261 static void mon_text_complete(void *data, struct urb *urb, int status)
 262 {
 263         struct mon_reader_text *rp = data;
 264         mon_text_event(rp, urb, 'C', status);
 265 }
 266
 267 static void mon_text_error(void *data, struct urb *urb, int error)
 268 {
 269         struct mon_reader_text *rp = data;
 270         struct mon_event_text *ep;
 271
 272         if (rp->nevents >= EVENT_MAX ||
 273             (ep = kmem_cache_alloc(rp->e_slab, GFP_ATOMIC)) == NULL) {
 274                 rp->r.m_bus->cnt_text_lost++;
 275                 return;
 276         }
 277
 278         ep->type = 'E';
 279         ep->id = (unsigned long) urb;
 280         ep->busnum = urb->dev->bus->busnum;
 281         ep->devnum = urb->dev->devnum;
 282         ep->epnum = usb_endpoint_num(&urb->ep->desc);
 283         ep->xfertype = usb_endpoint_type(&urb->ep->desc);
 284         ep->is_in = usb_urb_dir_in(urb);
 285         ep->tstamp = mon_get_timestamp();
 286         ep->length = 0;
 287         ep->status = error;
 288
 289         ep->setup_flag = '-';
 290         ep->data_flag = 'E';
 291
 292         rp->nevents++;
 293         list_add_tail(&ep->e_link, &rp->e_list);
 294         wake_up(&rp->wait);
 295 }
 296
 297 /*
 298  * Fetch next event from the circular buffer.
 299  */
 300 static struct mon_event_text *mon_text_fetch(struct mon_reader_text *rp,
 301     struct mon_bus *mbus)
 302 {
 303         struct list_head *p;
 304         unsigned long flags;
 305
 306         spin_lock_irqsave(&mbus->lock, flags);
 307         if (list_empty(&rp->e_list)) {
 308                 spin_unlock_irqrestore(&mbus->lock, flags);
 309                 return NULL;
 310         }
 311         p = rp->e_list.next;
 312         list_del(p);
 313         --rp->nevents;
 314         spin_unlock_irqrestore(&mbus->lock, flags);
 315         return list_entry(p, struct mon_event_text, e_link);
 316 }
 317
 318 /*
 319  */
 320 static int mon_text_open(struct inode *inode, struct file *file)
 321 {
 322         struct mon_bus *mbus;
 323         struct mon_reader_text *rp;
 324         int rc;
 325
 326         mutex_lock(&mon_lock);
 327         mbus = inode->i_private;
 328
 329         rp = kzalloc(sizeof(struct mon_reader_text), GFP_KERNEL);
 330         if (rp == NULL) {
 331                 rc = -ENOMEM;
 332                 goto err_alloc;
 333         }
 334         INIT_LIST_HEAD(&rp->e_list);
 335         init_waitqueue_head(&rp->wait);
 336         mutex_init(&rp->printf_lock);
 337
 338         rp->printf_size = PRINTF_DFL;
 339         rp->printf_buf = kmalloc(rp->printf_size, GFP_KERNEL);
 340         if (rp->printf_buf == NULL) {
 341                 rc = -ENOMEM;
 342                 goto err_alloc_pr;
 343         }
 344
 345         rp->r.m_bus = mbus;
 346         rp->r.r_data = rp;
 347         rp->r.rnf_submit = mon_text_submit;
 348         rp->r.rnf_error = mon_text_error;
 349         rp->r.rnf_complete = mon_text_complete;
 350
 351         snprintf(rp->slab_name, SLAB_NAME_SZ, "mon_text_%p", rp);
 352         rp->e_slab = kmem_cache_create(rp->slab_name,
 353             sizeof(struct mon_event_text), sizeof(long), 0,
 354             mon_text_ctor);
 355         if (rp->e_slab == NULL) {
 356                 rc = -ENOMEM;
 357                 goto err_slab;
 358         }
 359
 360         mon_reader_add(mbus, &rp->r);
 361
 362         file->private_data = rp;
 363         mutex_unlock(&mon_lock);
 364         return 0;
 365
 366 // err_busy:
 367 //      kmem_cache_destroy(rp->e_slab);
 368 err_slab:
 369         kfree(rp->printf_buf);
 370 err_alloc_pr:
 371         kfree(rp);
 372 err_alloc:
 373         mutex_unlock(&mon_lock);
 374         return rc;
 375 }
 376
 377 /*
 378  * For simplicity, we read one record in one system call and throw out
 379  * what does not fit. This means that the following does not work:
 380  *   dd if=/dbg/usbmon/0t bs=10
 381  * Also, we do not allow seeks and do not bother advancing the offset.
 382  */
 383 static ssize_t mon_text_read_t(struct file *file, char __user *buf,
 384                                 size_t nbytes, loff_t *ppos)
 385 {
 386         struct mon_reader_text *rp = file->private_data;
 387         struct mon_event_text *ep;
 388         struct mon_text_ptr ptr;
 389
 390         ep = mon_text_read_wait(rp, file);
 391         if (IS_ERR(ep))
 392                 return PTR_ERR(ep);
 393         mutex_lock(&rp->printf_lock);
 394         ptr.cnt = 0;
 395         ptr.pbuf = rp->printf_buf;
 396         ptr.limit = rp->printf_size;
 397
 398         mon_text_read_head_t(rp, &ptr, ep);
 399         mon_text_read_statset(rp, &ptr, ep);
 400         ptr.cnt += snprintf(ptr.pbuf + ptr.cnt, ptr.limit - ptr.cnt,
 401             " %d", ep->length);
 402         mon_text_read_data(rp, &ptr, ep);
 403
 404         if (copy_to_user(buf, rp->printf_buf, ptr.cnt))
 405                 ptr.cnt = -EFAULT;
 406         mutex_unlock(&rp->printf_lock);
 407         kmem_cache_free(rp->e_slab, ep);
 408         return ptr.cnt;
 409 }
 410
 411 static ssize_t mon_text_read_u(struct file *file, char __user *buf,
 412                                 size_t nbytes, loff_t *ppos)
 413 {
 414         struct mon_reader_text *rp = file->private_data;
 415         struct mon_event_text *ep;
 416         struct mon_text_ptr ptr;
 417
 418         ep = mon_text_read_wait(rp, file);
 419         if (IS_ERR(ep))
 420                 return PTR_ERR(ep);
 421         mutex_lock(&rp->printf_lock);
 422         ptr.cnt = 0;
 423         ptr.pbuf = rp->printf_buf;
 424         ptr.limit = rp->printf_size;
 425
 426         mon_text_read_head_u(rp, &ptr, ep);
 427         if (ep->type == 'E') {
 428                 mon_text_read_statset(rp, &ptr, ep);
 429         } else if (ep->xfertype == USB_ENDPOINT_XFER_ISOC) {
 430                 mon_text_read_isostat(rp, &ptr, ep);
 431                 mon_text_read_isodesc(rp, &ptr, ep);
 432         } else if (ep->xfertype == USB_ENDPOINT_XFER_INT) {
 433                 mon_text_read_intstat(rp, &ptr, ep);
 434         } else {
 435                 mon_text_read_statset(rp, &ptr, ep);
 436         }
 437         ptr.cnt += snprintf(ptr.pbuf + ptr.cnt, ptr.limit - ptr.cnt,
 438             " %d", ep->length);
 439         mon_text_read_data(rp, &ptr, ep);
 440
 441         if (copy_to_user(buf, rp->printf_buf, ptr.cnt))
 442                 ptr.cnt = -EFAULT;
 443         mutex_unlock(&rp->printf_lock);
 444         kmem_cache_free(rp->e_slab, ep);
 445         return ptr.cnt;
 446 }
 447
 448 static struct mon_event_text *mon_text_read_wait(struct mon_reader_text *rp,
 449     struct file *file)
 450 {
 451         struct mon_bus *mbus = rp->r.m_bus;
 452         DECLARE_WAITQUEUE(waita, current);
 453         struct mon_event_text *ep;
 454
 455         add_wait_queue(&rp->wait, &waita);
 456         set_current_state(TASK_INTERRUPTIBLE);
 457         while ((ep = mon_text_fetch(rp, mbus)) == NULL) {
 458                 if (file->f_flags & O_NONBLOCK) {
 459                         set_current_state(TASK_RUNNING);
 460                         remove_wait_queue(&rp->wait, &waita);
 461                         return ERR_PTR(-EWOULDBLOCK);
 462                 }
 463                 /*
 464                  * We do not count nwaiters, because ->release is supposed
 465                  * to be called when all openers are gone only.
 466                  */
 467                 schedule();
 468                 if (signal_pending(current)) {
 469                         remove_wait_queue(&rp->wait, &waita);
 470                         return ERR_PTR(-EINTR);
 471                 }
 472                 set_current_state(TASK_INTERRUPTIBLE);
 473         }
 474         set_current_state(TASK_RUNNING);
 475         remove_wait_queue(&rp->wait, &waita);
 476         return ep;
 477 }
 478
 479 static void mon_text_read_head_t(struct mon_reader_text *rp,
 480         struct mon_text_ptr *p, const struct mon_event_text *ep)
 481 {
 482         char udir, utype;
 483
 484         udir = (ep->is_in ? 'i' : 'o');
 485         switch (ep->xfertype) {
 486         case USB_ENDPOINT_XFER_ISOC:    utype = 'Z'; break;
 487         case USB_ENDPOINT_XFER_INT:     utype = 'I'; break;
 488         case USB_ENDPOINT_XFER_CONTROL: utype = 'C'; break;
 489         default: /* PIPE_BULK */  utype = 'B';
 490         }
 491         p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 492             "%lx %u %c %c%c:%03u:%02u",
 493             ep->id, ep->tstamp, ep->type,
 494             utype, udir, ep->devnum, ep->epnum);
 495 }
 496
 497 static void mon_text_read_head_u(struct mon_reader_text *rp,
 498         struct mon_text_ptr *p, const struct mon_event_text *ep)
 499 {
 500         char udir, utype;
 501
 502         udir = (ep->is_in ? 'i' : 'o');
 503         switch (ep->xfertype) {
 504         case USB_ENDPOINT_XFER_ISOC:    utype = 'Z'; break;
 505         case USB_ENDPOINT_XFER_INT:     utype = 'I'; break;
 506         case USB_ENDPOINT_XFER_CONTROL: utype = 'C'; break;
 507         default: /* PIPE_BULK */  utype = 'B';
 508         }
 509         p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 510             "%lx %u %c %c%c:%d:%03u:%u",
 511             ep->id, ep->tstamp, ep->type,
 512             utype, udir, ep->busnum, ep->devnum, ep->epnum);
 513 }
 514
 515 static void mon_text_read_statset(struct mon_reader_text *rp,
 516         struct mon_text_ptr *p, const struct mon_event_text *ep)
 517 {
 518
 519         if (ep->setup_flag == 0) {   /* Setup packet is present and captured */
 520                 p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 521                     " s %02x %02x %04x %04x %04x",
 522                     ep->setup[0],
 523                     ep->setup[1],
 524                     (ep->setup[3] << 8) | ep->setup[2],
 525                     (ep->setup[5] << 8) | ep->setup[4],
 526                     (ep->setup[7] << 8) | ep->setup[6]);
 527         } else if (ep->setup_flag != '-') { /* Unable to capture setup packet */
 528                 p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 529                     " %c __ __ ____ ____ ____", ep->setup_flag);
 530         } else {                     /* No setup for this kind of URB */
 531                 p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 532                     " %d", ep->status);
 533         }
 534 }
 535
 536 static void mon_text_read_intstat(struct mon_reader_text *rp,
 537         struct mon_text_ptr *p, const struct mon_event_text *ep)
 538 {
 539         p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 540             " %d:%d", ep->status, ep->interval);
 541 }
 542
 543 static void mon_text_read_isostat(struct mon_reader_text *rp,
 544         struct mon_text_ptr *p, const struct mon_event_text *ep)
 545 {
 546         if (ep->type == 'S') {
 547                 p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 548                     " %d:%d:%d", ep->status, ep->interval, ep->start_frame);
 549         } else {
 550                 p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 551                     " %d:%d:%d:%d",
 552                     ep->status, ep->interval, ep->start_frame, ep->error_count);
 553         }
 554 }
 555
 556 static void mon_text_read_isodesc(struct mon_reader_text *rp,
 557         struct mon_text_ptr *p, const struct mon_event_text *ep)
 558 {
 559         int ndesc;      /* Display this many */
 560         int i;
 561         const struct mon_iso_desc *dp;
 562
 563         p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 564             " %d", ep->numdesc);
 565         ndesc = ep->numdesc;
 566         if (ndesc > ISODESC_MAX)
 567                 ndesc = ISODESC_MAX;
 568         if (ndesc < 0)
 569                 ndesc = 0;
 570         dp = ep->isodesc;
 571         for (i = 0; i < ndesc; i++) {
 572                 p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 573                     " %d:%u:%u", dp->status, dp->offset, dp->length);
 574                 dp++;
 575         }
 576 }
 577
 578 static void mon_text_read_data(struct mon_reader_text *rp,
 579     struct mon_text_ptr *p, const struct mon_event_text *ep)
 580 {
 581         int data_len, i;
 582
 583         if ((data_len = ep->length) > 0) {
 584                 if (ep->data_flag == 0) {
 585                         p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 586                             " =");
 587                         if (data_len >= DATA_MAX)
 588                                 data_len = DATA_MAX;
 589                         for (i = 0; i < data_len; i++) {
 590                                 if (i % 4 == 0) {
 591                                         p->cnt += snprintf(p->pbuf + p->cnt,
 592                                             p->limit - p->cnt,
 593                                             " ");
 594                                 }
 595                                 p->cnt += snprintf(p->pbuf + p->cnt,
 596                                     p->limit - p->cnt,
 597                                     "%02x", ep->data[i]);
 598                         }
 599                         p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 600                             "\n");
 601                 } else {
 602                         p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 603                             " %c\n", ep->data_flag);
 604                 }
 605         } else {
 606                 p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt, "\n");
 607         }
 608 }
 609
 610 static int mon_text_release(struct inode *inode, struct file *file)
 611 {
 612         struct mon_reader_text *rp = file->private_data;
 613         struct mon_bus *mbus;
 614         /* unsigned long flags; */
 615         struct list_head *p;
 616         struct mon_event_text *ep;
 617
 618         mutex_lock(&mon_lock);
 619         mbus = inode->i_private;
 620
 621         if (mbus->nreaders <= 0) {
 622                 printk(KERN_ERR TAG ": consistency error on close\n");
 623                 mutex_unlock(&mon_lock);
 624                 return 0;
 625         }
 626         mon_reader_del(mbus, &rp->r);
 627
 628         /*
 629          * In theory, e_list is protected by mbus->lock. However,
 630          * after mon_reader_del has finished, the following is the case:
 631          *  - we are not on reader list anymore, so new events won't be added;
 632          *  - whole mbus may be dropped if it was orphaned.
 633          * So, we better not touch mbus.
 634          */
 635         /* spin_lock_irqsave(&mbus->lock, flags); */
 636         while (!list_empty(&rp->e_list)) {
 637                 p = rp->e_list.next;
 638                 ep = list_entry(p, struct mon_event_text, e_link);
 639                 list_del(p);
 640                 --rp->nevents;
 641                 kmem_cache_free(rp->e_slab, ep);
 642         }
 643         /* spin_unlock_irqrestore(&mbus->lock, flags); */
 644
 645         kmem_cache_destroy(rp->e_slab);
 646         kfree(rp->printf_buf);
 647         kfree(rp);
 648
 649         mutex_unlock(&mon_lock);
 650         return 0;
 651 }
 652
 653 static const struct file_operations mon_fops_text_t = {
 654         .owner =        THIS_MODULE,
 655         .open =         mon_text_open,
 656         .llseek =       no_llseek,
 657         .read =         mon_text_read_t,
 658         .release =      mon_text_release,
 659 };
 660
 661 static const struct file_operations mon_fops_text_u = {
 662         .owner =        THIS_MODULE,
 663         .open =         mon_text_open,
 664         .llseek =       no_llseek,
 665         .read =         mon_text_read_u,
 666         .release =      mon_text_release,
 667 };
 668
 669 int mon_text_add(struct mon_bus *mbus, const struct usb_bus *ubus)
 670 {
 671         struct dentry *d;
 672         enum { NAMESZ = 10 };
 673         char name[NAMESZ];
 674         int busnum = ubus? ubus->busnum: 0;
 675         int rc;
 676
 677         if (mon_dir == NULL)
 678                 return 0;
 679
 680         if (ubus != NULL) {
 681                 rc = snprintf(name, NAMESZ, "%dt", busnum);
 682                 if (rc <= 0 || rc >= NAMESZ)
 683                         goto err_print_t;
 684                 d = debugfs_create_file(name, 0600, mon_dir, mbus,
 685                                                              &mon_fops_text_t);
 686                 if (d == NULL)
 687                         goto err_create_t;
 688                 mbus->dent_t = d;
 689         }
 690
 691         rc = snprintf(name, NAMESZ, "%du", busnum);
 692         if (rc <= 0 || rc >= NAMESZ)
 693                 goto err_print_u;
 694         d = debugfs_create_file(name, 0600, mon_dir, mbus, &mon_fops_text_u);
 695         if (d == NULL)
 696                 goto err_create_u;
 697         mbus->dent_u = d;
 698
 699         rc = snprintf(name, NAMESZ, "%ds", busnum);
 700         if (rc <= 0 || rc >= NAMESZ)
 701                 goto err_print_s;
 702         d = debugfs_create_file(name, 0600, mon_dir, mbus, &mon_fops_stat);
 703         if (d == NULL)
 704                 goto err_create_s;
 705         mbus->dent_s = d;
 706
 707         return 1;
 708
 709 err_create_s:
 710 err_print_s:
 711         debugfs_remove(mbus->dent_u);
 712         mbus->dent_u = NULL;
 713 err_create_u:
 714 err_print_u:
 715         if (ubus != NULL) {
 716                 debugfs_remove(mbus->dent_t);
 717                 mbus->dent_t = NULL;
 718         }
 719 err_create_t:
 720 err_print_t:
 721         return 0;
 722 }
 723
 724 void mon_text_del(struct mon_bus *mbus)
 725 {
 726         debugfs_remove(mbus->dent_u);
 727         if (mbus->dent_t != NULL)
 728                 debugfs_remove(mbus->dent_t);
 729         debugfs_remove(mbus->dent_s);
 730 }
 731
 732 /*
 733  * Slab interface: constructor.
 734  */
 735 static void mon_text_ctor(void *mem)
 736 {
 737         /*
 738          * Nothing to initialize. No, really!
 739          * So, we fill it with garbage to emulate a reused object.
 740          */
 741         memset(mem, 0xe5, sizeof(struct mon_event_text));
 742 }
 743
 744 int __init mon_text_init(void)
 745 {
 746         struct dentry *mondir;
 747
 748         mondir = debugfs_create_dir("usbmon", usb_debug_root);
 749         if (IS_ERR(mondir)) {
 750                 /* debugfs not available, but we can use usbmon without it */
 751                 return 0;
 752         }
 753         if (mondir == NULL) {
 754                 printk(KERN_NOTICE TAG ": unable to create usbmon directory\n");
 755                 return -ENOMEM;
 756         }
 757         mon_dir = mondir;
 758         return 0;
 759 }
 760
 761 void mon_text_exit(void)
 762 {
 763         debugfs_remove(mon_dir);
 764 }