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