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/time.h>
  11 #include <linux/mutex.h>
  12 #include <linux/debugfs.h>
  13 #include <linux/scatterlist.h>
  14 #include <asm/uaccess.h>
  15
  16 #include "usb_mon.h"
  17
  18 /*
  19  * No, we do not want arbitrarily long data strings.
  20  * Use the binary interface if you want to capture bulk data!
  21  */
  22 #define DATA_MAX  32
  23
  24 /*
  25  * Defined by USB 2.0 clause 9.3, table 9.2.
  26  */
  27 #define SETUP_MAX  8
  28
  29 /*
  30  * This limit exists to prevent OOMs when the user process stops reading.
  31  * If usbmon were available to unprivileged processes, it might be open
  32  * to a local DoS. But we have to keep to root in order to prevent
  33  * password sniffing from HID devices.
  34  */
  35 #define EVENT_MAX  (4*PAGE_SIZE / sizeof(struct mon_event_text))
  36
  37 /*
  38  * Potentially unlimited number; we limit it for similar allocations.
  39  * The usbfs limits this to 128, but we're not quite as generous.
  40  */
  41 #define ISODESC_MAX   5
  42
  43 #define PRINTF_DFL  250   /* with 5 ISOs segs */
  44
  45 struct mon_iso_desc {
  46         int status;
  47         unsigned int offset;
  48         unsigned int length;    /* Unsigned here, signed in URB. Historic. */
  49 };
  50
  51 struct mon_event_text {
  52         struct list_head e_link;
  53         int type;               /* submit, complete, etc. */
  54         unsigned long id;       /* From pointer, most of the time */
  55         unsigned int tstamp;
  56         int busnum;
  57         char devnum;
  58         char epnum;
  59         char is_in;
  60         char xfertype;
  61         int length;             /* Depends on type: xfer length or act length */
  62         int status;
  63         int interval;
  64         int start_frame;
  65         int error_count;
  66         char setup_flag;
  67         char data_flag;
  68         int numdesc;            /* Full number */
  69         struct mon_iso_desc isodesc[ISODESC_MAX];
  70         unsigned char setup[SETUP_MAX];
  71         unsigned char data[DATA_MAX];
  72 };
  73
  74 #define SLAB_NAME_SZ  30
  75 struct mon_reader_text {
  76         struct kmem_cache *e_slab;
  77         int nevents;
  78         struct list_head e_list;
  79         struct mon_reader r;    /* In C, parent class can be placed anywhere */
  80
  81         wait_queue_head_t wait;
  82         int printf_size;
  83         char *printf_buf;
  84         struct mutex printf_lock;
  85
  86         char slab_name[SLAB_NAME_SZ];
  87 };
  88
  89 static struct dentry *mon_dir;          /* Usually /sys/kernel/debug/usbmon */
  90
  91 static void mon_text_ctor(void *);
  92
  93 struct mon_text_ptr {
  94         int cnt, limit;
  95         char *pbuf;
  96 };
  97
  98 static struct mon_event_text *
  99     mon_text_read_wait(struct mon_reader_text *rp, struct file *file);
 100 static void mon_text_read_head_t(struct mon_reader_text *rp,
 101         struct mon_text_ptr *p, const struct mon_event_text *ep);
 102 static void mon_text_read_head_u(struct mon_reader_text *rp,
 103         struct mon_text_ptr *p, const struct mon_event_text *ep);
 104 static void mon_text_read_statset(struct mon_reader_text *rp,
 105         struct mon_text_ptr *p, const struct mon_event_text *ep);
 106 static void mon_text_read_intstat(struct mon_reader_text *rp,
 107         struct mon_text_ptr *p, const struct mon_event_text *ep);
 108 static void mon_text_read_isostat(struct mon_reader_text *rp,
 109         struct mon_text_ptr *p, const struct mon_event_text *ep);
 110 static void mon_text_read_isodesc(struct mon_reader_text *rp,
 111         struct mon_text_ptr *p, const struct mon_event_text *ep);
 112 static void mon_text_read_data(struct mon_reader_text *rp,
 113     struct mon_text_ptr *p, const struct mon_event_text *ep);
 114
 115 /*
 116  * mon_text_submit
 117  * mon_text_complete
 118  *
 119  * May be called from an interrupt.
 120  *
 121  * This is called with the whole mon_bus locked, so no additional lock.
 122  */
 123
 124 static inline char mon_text_get_setup(struct mon_event_text *ep,
 125     struct urb *urb, char ev_type, struct mon_bus *mbus)
 126 {
 127
 128         if (ep->xfertype != USB_ENDPOINT_XFER_CONTROL || ev_type != 'S')
 129                 return '-';
 130
 131         if (urb->setup_packet == NULL)
 132                 return 'Z';     /* '0' would be not as pretty. */
 133
 134         memcpy(ep->setup, urb->setup_packet, SETUP_MAX);
 135         return 0;
 136 }
 137
 138 static inline char mon_text_get_data(struct mon_event_text *ep, struct urb *urb,
 139     int len, char ev_type, struct mon_bus *mbus)
 140 {
 141         void *src;
 142
 143         if (len <= 0)
 144                 return 'L';
 145         if (len >= DATA_MAX)
 146                 len = DATA_MAX;
 147
 148         if (ep->is_in) {
 149                 if (ev_type != 'C')
 150                         return '<';
 151         } else {
 152                 if (ev_type != 'S')
 153                         return '>';
 154         }
 155
 156         if (urb->num_sgs == 0) {
 157                 src = urb->transfer_buffer;
 158                 if (src == NULL)
 159                         return 'Z';     /* '0' would be not as pretty. */
 160         } else {
 161                 struct scatterlist *sg = urb->sg->sg;
 162
 163                 /* If IOMMU coalescing occurred, we cannot trust sg_page */
 164                 if (urb->sg->nents != urb->num_sgs ||
 165                                 PageHighMem(sg_page(sg)))
 166                         return 'D';
 167
 168                 /* For the text interface we copy only the first sg buffer */
 169                 len = min_t(int, sg->length, len);
 170                 src = sg_virt(sg);
 171         }
 172
 173         memcpy(ep->data, src, len);
 174         return 0;
 175 }
 176
 177 static inline unsigned int mon_get_timestamp(void)
 178 {
 179         struct timeval tval;
 180         unsigned int stamp;
 181
 182         do_gettimeofday(&tval);
 183         stamp = tval.tv_sec & 0xFFFF;   /* 2^32 = 4294967296. Limit to 4096s. */
 184         stamp = stamp * 1000000 + tval.tv_usec;
 185         return stamp;
 186 }
 187
 188 static void mon_text_event(struct mon_reader_text *rp, struct urb *urb,
 189     char ev_type, int status)
 190 {
 191         struct mon_event_text *ep;
 192         unsigned int stamp;
 193         struct usb_iso_packet_descriptor *fp;
 194         struct mon_iso_desc *dp;
 195         int i, ndesc;
 196
 197         stamp = mon_get_timestamp();
 198
 199         if (rp->nevents >= EVENT_MAX ||
 200             (ep = kmem_cache_alloc(rp->e_slab, GFP_ATOMIC)) == NULL) {
 201                 rp->r.m_bus->cnt_text_lost++;
 202                 return;
 203         }
 204
 205         ep->type = ev_type;
 206         ep->id = (unsigned long) urb;
 207         ep->busnum = urb->dev->bus->busnum;
 208         ep->devnum = urb->dev->devnum;
 209         ep->epnum = usb_endpoint_num(&urb->ep->desc);
 210         ep->xfertype = usb_endpoint_type(&urb->ep->desc);
 211         ep->is_in = usb_urb_dir_in(urb);
 212         ep->tstamp = stamp;
 213         ep->length = (ev_type == 'S') ?
 214             urb->transfer_buffer_length : urb->actual_length;
 215         /* Collecting status makes debugging sense for submits, too */
 216         ep->status = status;
 217
 218         if (ep->xfertype == USB_ENDPOINT_XFER_INT) {
 219                 ep->interval = urb->interval;
 220         } else if (ep->xfertype == USB_ENDPOINT_XFER_ISOC) {
 221                 ep->interval = urb->interval;
 222                 ep->start_frame = urb->start_frame;
 223                 ep->error_count = urb->error_count;
 224         }
 225         ep->numdesc = urb->number_of_packets;
 226         if (ep->xfertype == USB_ENDPOINT_XFER_ISOC &&
 227                         urb->number_of_packets > 0) {
 228                 if ((ndesc = urb->number_of_packets) > ISODESC_MAX)
 229                         ndesc = ISODESC_MAX;
 230                 fp = urb->iso_frame_desc;
 231                 dp = ep->isodesc;
 232                 for (i = 0; i < ndesc; i++) {
 233                         dp->status = fp->status;
 234                         dp->offset = fp->offset;
 235                         dp->length = (ev_type == 'S') ?
 236                             fp->length : fp->actual_length;
 237                         fp++;
 238                         dp++;
 239                 }
 240         }
 241
 242         ep->setup_flag = mon_text_get_setup(ep, urb, ev_type, rp->r.m_bus);
 243         ep->data_flag = mon_text_get_data(ep, urb, ep->length, ev_type,
 244                         rp->r.m_bus);
 245
 246         rp->nevents++;
 247         list_add_tail(&ep->e_link, &rp->e_list);
 248         wake_up(&rp->wait);
 249 }
 250
 251 static void mon_text_submit(void *data, struct urb *urb)
 252 {
 253         struct mon_reader_text *rp = data;
 254         mon_text_event(rp, urb, 'S', -EINPROGRESS);
 255 }
 256
 257 static void mon_text_complete(void *data, struct urb *urb, int status)
 258 {
 259         struct mon_reader_text *rp = data;
 260         mon_text_event(rp, urb, 'C', status);
 261 }
 262
 263 static void mon_text_error(void *data, struct urb *urb, int error)
 264 {
 265         struct mon_reader_text *rp = data;
 266         struct mon_event_text *ep;
 267
 268         if (rp->nevents >= EVENT_MAX ||
 269             (ep = kmem_cache_alloc(rp->e_slab, GFP_ATOMIC)) == NULL) {
 270                 rp->r.m_bus->cnt_text_lost++;
 271                 return;
 272         }
 273
 274         ep->type = 'E';
 275         ep->id = (unsigned long) urb;
 276         ep->busnum = 0;
 277         ep->devnum = urb->dev->devnum;
 278         ep->epnum = usb_endpoint_num(&urb->ep->desc);
 279         ep->xfertype = usb_endpoint_type(&urb->ep->desc);
 280         ep->is_in = usb_urb_dir_in(urb);
 281         ep->tstamp = 0;
 282         ep->length = 0;
 283         ep->status = error;
 284
 285         ep->setup_flag = '-';
 286         ep->data_flag = 'E';
 287
 288         rp->nevents++;
 289         list_add_tail(&ep->e_link, &rp->e_list);
 290         wake_up(&rp->wait);
 291 }
 292
 293 /*
 294  * Fetch next event from the circular buffer.
 295  */
 296 static struct mon_event_text *mon_text_fetch(struct mon_reader_text *rp,
 297     struct mon_bus *mbus)
 298 {
 299         struct list_head *p;
 300         unsigned long flags;
 301
 302         spin_lock_irqsave(&mbus->lock, flags);
 303         if (list_empty(&rp->e_list)) {
 304                 spin_unlock_irqrestore(&mbus->lock, flags);
 305                 return NULL;
 306         }
 307         p = rp->e_list.next;
 308         list_del(p);
 309         --rp->nevents;
 310         spin_unlock_irqrestore(&mbus->lock, flags);
 311         return list_entry(p, struct mon_event_text, e_link);
 312 }
 313
 314 /*
 315  */
 316 static int mon_text_open(struct inode *inode, struct file *file)
 317 {
 318         struct mon_bus *mbus;
 319         struct mon_reader_text *rp;
 320         int rc;
 321
 322         mutex_lock(&mon_lock);
 323         mbus = inode->i_private;
 324
 325         rp = kzalloc(sizeof(struct mon_reader_text), GFP_KERNEL);
 326         if (rp == NULL) {
 327                 rc = -ENOMEM;
 328                 goto err_alloc;
 329         }
 330         INIT_LIST_HEAD(&rp->e_list);
 331         init_waitqueue_head(&rp->wait);
 332         mutex_init(&rp->printf_lock);
 333
 334         rp->printf_size = PRINTF_DFL;
 335         rp->printf_buf = kmalloc(rp->printf_size, GFP_KERNEL);
 336         if (rp->printf_buf == NULL) {
 337                 rc = -ENOMEM;
 338                 goto err_alloc_pr;
 339         }
 340
 341         rp->r.m_bus = mbus;
 342         rp->r.r_data = rp;
 343         rp->r.rnf_submit = mon_text_submit;
 344         rp->r.rnf_error = mon_text_error;
 345         rp->r.rnf_complete = mon_text_complete;
 346
 347         snprintf(rp->slab_name, SLAB_NAME_SZ, "mon_text_%p", rp);
 348         rp->e_slab = kmem_cache_create(rp->slab_name,
 349             sizeof(struct mon_event_text), sizeof(long), 0,
 350             mon_text_ctor);
 351         if (rp->e_slab == NULL) {
 352                 rc = -ENOMEM;
 353                 goto err_slab;
 354         }
 355
 356         mon_reader_add(mbus, &rp->r);
 357
 358         file->private_data = rp;
 359         mutex_unlock(&mon_lock);
 360         return 0;
 361
 362 // err_busy:
 363 //      kmem_cache_destroy(rp->e_slab);
 364 err_slab:
 365         kfree(rp->printf_buf);
 366 err_alloc_pr:
 367         kfree(rp);
 368 err_alloc:
 369         mutex_unlock(&mon_lock);
 370         return rc;
 371 }
 372
 373 /*
 374  * For simplicity, we read one record in one system call and throw out
 375  * what does not fit. This means that the following does not work:
 376  *   dd if=/dbg/usbmon/0t bs=10
 377  * Also, we do not allow seeks and do not bother advancing the offset.
 378  */
 379 static ssize_t mon_text_read_t(struct file *file, char __user *buf,
 380                                 size_t nbytes, loff_t *ppos)
 381 {
 382         struct mon_reader_text *rp = file->private_data;
 383         struct mon_event_text *ep;
 384         struct mon_text_ptr ptr;
 385
 386         if (IS_ERR(ep = mon_text_read_wait(rp, file)))
 387                 return PTR_ERR(ep);
 388         mutex_lock(&rp->printf_lock);
 389         ptr.cnt = 0;
 390         ptr.pbuf = rp->printf_buf;
 391         ptr.limit = rp->printf_size;
 392
 393         mon_text_read_head_t(rp, &ptr, ep);
 394         mon_text_read_statset(rp, &ptr, ep);
 395         ptr.cnt += snprintf(ptr.pbuf + ptr.cnt, ptr.limit - ptr.cnt,
 396             " %d", ep->length);
 397         mon_text_read_data(rp, &ptr, ep);
 398
 399         if (copy_to_user(buf, rp->printf_buf, ptr.cnt))
 400                 ptr.cnt = -EFAULT;
 401         mutex_unlock(&rp->printf_lock);
 402         kmem_cache_free(rp->e_slab, ep);
 403         return ptr.cnt;
 404 }
 405
 406 static ssize_t mon_text_read_u(struct file *file, char __user *buf,
 407                                 size_t nbytes, loff_t *ppos)
 408 {
 409         struct mon_reader_text *rp = file->private_data;
 410         struct mon_event_text *ep;
 411         struct mon_text_ptr ptr;
 412
 413         if (IS_ERR(ep = mon_text_read_wait(rp, file)))
 414                 return PTR_ERR(ep);
 415         mutex_lock(&rp->printf_lock);
 416         ptr.cnt = 0;
 417         ptr.pbuf = rp->printf_buf;
 418         ptr.limit = rp->printf_size;
 419
 420         mon_text_read_head_u(rp, &ptr, ep);
 421         if (ep->type == 'E') {
 422                 mon_text_read_statset(rp, &ptr, ep);
 423         } else if (ep->xfertype == USB_ENDPOINT_XFER_ISOC) {
 424                 mon_text_read_isostat(rp, &ptr, ep);
 425                 mon_text_read_isodesc(rp, &ptr, ep);
 426         } else if (ep->xfertype == USB_ENDPOINT_XFER_INT) {
 427                 mon_text_read_intstat(rp, &ptr, ep);
 428         } else {
 429                 mon_text_read_statset(rp, &ptr, ep);
 430         }
 431         ptr.cnt += snprintf(ptr.pbuf + ptr.cnt, ptr.limit - ptr.cnt,
 432             " %d", ep->length);
 433         mon_text_read_data(rp, &ptr, ep);
 434
 435         if (copy_to_user(buf, rp->printf_buf, ptr.cnt))
 436                 ptr.cnt = -EFAULT;
 437         mutex_unlock(&rp->printf_lock);
 438         kmem_cache_free(rp->e_slab, ep);
 439         return ptr.cnt;
 440 }
 441
 442 static struct mon_event_text *mon_text_read_wait(struct mon_reader_text *rp,
 443     struct file *file)
 444 {
 445         struct mon_bus *mbus = rp->r.m_bus;
 446         DECLARE_WAITQUEUE(waita, current);
 447         struct mon_event_text *ep;
 448
 449         add_wait_queue(&rp->wait, &waita);
 450         set_current_state(TASK_INTERRUPTIBLE);
 451         while ((ep = mon_text_fetch(rp, mbus)) == NULL) {
 452                 if (file->f_flags & O_NONBLOCK) {
 453                         set_current_state(TASK_RUNNING);
 454                         remove_wait_queue(&rp->wait, &waita);
 455                         return ERR_PTR(-EWOULDBLOCK);
 456                 }
 457                 /*
 458                  * We do not count nwaiters, because ->release is supposed
 459                  * to be called when all openers are gone only.
 460                  */
 461                 schedule();
 462                 if (signal_pending(current)) {
 463                         remove_wait_queue(&rp->wait, &waita);
 464                         return ERR_PTR(-EINTR);
 465                 }
 466                 set_current_state(TASK_INTERRUPTIBLE);
 467         }
 468         set_current_state(TASK_RUNNING);
 469         remove_wait_queue(&rp->wait, &waita);
 470         return ep;
 471 }
 472
 473 static void mon_text_read_head_t(struct mon_reader_text *rp,
 474         struct mon_text_ptr *p, const struct mon_event_text *ep)
 475 {
 476         char udir, utype;
 477
 478         udir = (ep->is_in ? 'i' : 'o');
 479         switch (ep->xfertype) {
 480         case USB_ENDPOINT_XFER_ISOC:    utype = 'Z'; break;
 481         case USB_ENDPOINT_XFER_INT:     utype = 'I'; break;
 482         case USB_ENDPOINT_XFER_CONTROL: utype = 'C'; break;
 483         default: /* PIPE_BULK */  utype = 'B';
 484         }
 485         p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 486             "%lx %u %c %c%c:%03u:%02u",
 487             ep->id, ep->tstamp, ep->type,
 488             utype, udir, ep->devnum, ep->epnum);
 489 }
 490
 491 static void mon_text_read_head_u(struct mon_reader_text *rp,
 492         struct mon_text_ptr *p, const struct mon_event_text *ep)
 493 {
 494         char udir, utype;
 495
 496         udir = (ep->is_in ? 'i' : 'o');
 497         switch (ep->xfertype) {
 498         case USB_ENDPOINT_XFER_ISOC:    utype = 'Z'; break;
 499         case USB_ENDPOINT_XFER_INT:     utype = 'I'; break;
 500         case USB_ENDPOINT_XFER_CONTROL: utype = 'C'; break;
 501         default: /* PIPE_BULK */  utype = 'B';
 502         }
 503         p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 504             "%lx %u %c %c%c:%d:%03u:%u",
 505             ep->id, ep->tstamp, ep->type,
 506             utype, udir, ep->busnum, ep->devnum, ep->epnum);
 507 }
 508
 509 static void mon_text_read_statset(struct mon_reader_text *rp,
 510         struct mon_text_ptr *p, const struct mon_event_text *ep)
 511 {
 512
 513         if (ep->setup_flag == 0) {   /* Setup packet is present and captured */
 514                 p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 515                     " s %02x %02x %04x %04x %04x",
 516                     ep->setup[0],
 517                     ep->setup[1],
 518                     (ep->setup[3] << 8) | ep->setup[2],
 519                     (ep->setup[5] << 8) | ep->setup[4],
 520                     (ep->setup[7] << 8) | ep->setup[6]);
 521         } else if (ep->setup_flag != '-') { /* Unable to capture setup packet */
 522                 p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 523                     " %c __ __ ____ ____ ____", ep->setup_flag);
 524         } else {                     /* No setup for this kind of URB */
 525                 p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 526                     " %d", ep->status);
 527         }
 528 }
 529
 530 static void mon_text_read_intstat(struct mon_reader_text *rp,
 531         struct mon_text_ptr *p, const struct mon_event_text *ep)
 532 {
 533         p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 534             " %d:%d", ep->status, ep->interval);
 535 }
 536
 537 static void mon_text_read_isostat(struct mon_reader_text *rp,
 538         struct mon_text_ptr *p, const struct mon_event_text *ep)
 539 {
 540         if (ep->type == 'S') {
 541                 p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 542                     " %d:%d:%d", ep->status, ep->interval, ep->start_frame);
 543         } else {
 544                 p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 545                     " %d:%d:%d:%d",
 546                     ep->status, ep->interval, ep->start_frame, ep->error_count);
 547         }
 548 }
 549
 550 static void mon_text_read_isodesc(struct mon_reader_text *rp,
 551         struct mon_text_ptr *p, const struct mon_event_text *ep)
 552 {
 553         int ndesc;      /* Display this many */
 554         int i;
 555         const struct mon_iso_desc *dp;
 556
 557         p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 558             " %d", ep->numdesc);
 559         ndesc = ep->numdesc;
 560         if (ndesc > ISODESC_MAX)
 561                 ndesc = ISODESC_MAX;
 562         if (ndesc < 0)
 563                 ndesc = 0;
 564         dp = ep->isodesc;
 565         for (i = 0; i < ndesc; i++) {
 566                 p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 567                     " %d:%u:%u", dp->status, dp->offset, dp->length);
 568                 dp++;
 569         }
 570 }
 571
 572 static void mon_text_read_data(struct mon_reader_text *rp,
 573     struct mon_text_ptr *p, const struct mon_event_text *ep)
 574 {
 575         int data_len, i;
 576
 577         if ((data_len = ep->length) > 0) {
 578                 if (ep->data_flag == 0) {
 579                         p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 580                             " =");
 581                         if (data_len >= DATA_MAX)
 582                                 data_len = DATA_MAX;
 583                         for (i = 0; i < data_len; i++) {
 584                                 if (i % 4 == 0) {
 585                                         p->cnt += snprintf(p->pbuf + p->cnt,
 586                                             p->limit - p->cnt,
 587                                             " ");
 588                                 }
 589                                 p->cnt += snprintf(p->pbuf + p->cnt,
 590                                     p->limit - p->cnt,
 591                                     "%02x", ep->data[i]);
 592                         }
 593                         p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 594                             "\n");
 595                 } else {
 596                         p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 597                             " %c\n", ep->data_flag);
 598                 }
 599         } else {
 600                 p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt, "\n");
 601         }
 602 }
 603
 604 static int mon_text_release(struct inode *inode, struct file *file)
 605 {
 606         struct mon_reader_text *rp = file->private_data;
 607         struct mon_bus *mbus;
 608         /* unsigned long flags; */
 609         struct list_head *p;
 610         struct mon_event_text *ep;
 611
 612         mutex_lock(&mon_lock);
 613         mbus = inode->i_private;
 614
 615         if (mbus->nreaders <= 0) {
 616                 printk(KERN_ERR TAG ": consistency error on close\n");
 617                 mutex_unlock(&mon_lock);
 618                 return 0;
 619         }
 620         mon_reader_del(mbus, &rp->r);
 621
 622         /*
 623          * In theory, e_list is protected by mbus->lock. However,
 624          * after mon_reader_del has finished, the following is the case:
 625          *  - we are not on reader list anymore, so new events won't be added;
 626          *  - whole mbus may be dropped if it was orphaned.
 627          * So, we better not touch mbus.
 628          */
 629         /* spin_lock_irqsave(&mbus->lock, flags); */
 630         while (!list_empty(&rp->e_list)) {
 631                 p = rp->e_list.next;
 632                 ep = list_entry(p, struct mon_event_text, e_link);
 633                 list_del(p);
 634                 --rp->nevents;
 635                 kmem_cache_free(rp->e_slab, ep);
 636         }
 637         /* spin_unlock_irqrestore(&mbus->lock, flags); */
 638
 639         kmem_cache_destroy(rp->e_slab);
 640         kfree(rp->printf_buf);
 641         kfree(rp);
 642
 643         mutex_unlock(&mon_lock);
 644         return 0;
 645 }
 646
 647 static const struct file_operations mon_fops_text_t = {
 648         .owner =        THIS_MODULE,
 649         .open =         mon_text_open,
 650         .llseek =       no_llseek,
 651         .read =         mon_text_read_t,
 652         .release =      mon_text_release,
 653 };
 654
 655 static const struct file_operations mon_fops_text_u = {
 656         .owner =        THIS_MODULE,
 657         .open =         mon_text_open,
 658         .llseek =       no_llseek,
 659         .read =         mon_text_read_u,
 660         .release =      mon_text_release,
 661 };
 662
 663 int mon_text_add(struct mon_bus *mbus, const struct usb_bus *ubus)
 664 {
 665         struct dentry *d;
 666         enum { NAMESZ = 10 };
 667         char name[NAMESZ];
 668         int busnum = ubus? ubus->busnum: 0;
 669         int rc;
 670
 671         if (ubus != NULL) {
 672                 rc = snprintf(name, NAMESZ, "%dt", busnum);
 673                 if (rc <= 0 || rc >= NAMESZ)
 674                         goto err_print_t;
 675                 d = debugfs_create_file(name, 0600, mon_dir, mbus,
 676                                                              &mon_fops_text_t);
 677                 if (d == NULL)
 678                         goto err_create_t;
 679                 mbus->dent_t = d;
 680         }
 681
 682         rc = snprintf(name, NAMESZ, "%du", busnum);
 683         if (rc <= 0 || rc >= NAMESZ)
 684                 goto err_print_u;
 685         d = debugfs_create_file(name, 0600, mon_dir, mbus, &mon_fops_text_u);
 686         if (d == NULL)
 687                 goto err_create_u;
 688         mbus->dent_u = d;
 689
 690         rc = snprintf(name, NAMESZ, "%ds", busnum);
 691         if (rc <= 0 || rc >= NAMESZ)
 692                 goto err_print_s;
 693         d = debugfs_create_file(name, 0600, mon_dir, mbus, &mon_fops_stat);
 694         if (d == NULL)
 695                 goto err_create_s;
 696         mbus->dent_s = d;
 697
 698         return 1;
 699
 700 err_create_s:
 701 err_print_s:
 702         debugfs_remove(mbus->dent_u);
 703         mbus->dent_u = NULL;
 704 err_create_u:
 705 err_print_u:
 706         if (ubus != NULL) {
 707                 debugfs_remove(mbus->dent_t);
 708                 mbus->dent_t = NULL;
 709         }
 710 err_create_t:
 711 err_print_t:
 712         return 0;
 713 }
 714
 715 void mon_text_del(struct mon_bus *mbus)
 716 {
 717         debugfs_remove(mbus->dent_u);
 718         if (mbus->dent_t != NULL)
 719                 debugfs_remove(mbus->dent_t);
 720         debugfs_remove(mbus->dent_s);
 721 }
 722
 723 /*
 724  * Slab interface: constructor.
 725  */
 726 static void mon_text_ctor(void *mem)
 727 {
 728         /*
 729          * Nothing to initialize. No, really!
 730          * So, we fill it with garbage to emulate a reused object.
 731          */
 732         memset(mem, 0xe5, sizeof(struct mon_event_text));
 733 }
 734
 735 int __init mon_text_init(void)
 736 {
 737         struct dentry *mondir;
 738
 739         mondir = debugfs_create_dir("usbmon", usb_debug_root);
 740         if (IS_ERR(mondir)) {
 741                 printk(KERN_NOTICE TAG ": debugfs is not available\n");
 742                 return -ENODEV;
 743         }
 744         if (mondir == NULL) {
 745                 printk(KERN_NOTICE TAG ": unable to create usbmon directory\n");
 746                 return -ENODEV;
 747         }
 748         mon_dir = mondir;
 749         return 0;
 750 }
 751
 752 void mon_text_exit(void)
 753 {
 754         debugfs_remove(mon_dir);
 755 }