drivers/usb/mon/mon_text.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * The USB Monitor, inspired by Dave Harding's USBMon.
   4  *
   5  * This is a text format reader.
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/list.h>
  10 #include <linux/usb.h>
  11 #include <linux/slab.h>
  12 #include <linux/sched/signal.h>
  13 #include <linux/time.h>
  14 #include <linux/ktime.h>
  15 #include <linux/export.h>
  16 #include <linux/mutex.h>
  17 #include <linux/debugfs.h>
  18 #include <linux/scatterlist.h>
  19 #include <linux/uaccess.h>
  20
  21 #include "usb_mon.h"
  22
  23 /*
  24  * No, we do not want arbitrarily long data strings.
  25  * Use the binary interface if you want to capture bulk data!
  26  */
  27 #define DATA_MAX  32
  28
  29 /*
  30  * Defined by USB 2.0 clause 9.3, table 9.2.
  31  */
  32 #define SETUP_MAX  8
  33
  34 /*
  35  * This limit exists to prevent OOMs when the user process stops reading.
  36  * If usbmon were available to unprivileged processes, it might be open
  37  * to a local DoS. But we have to keep to root in order to prevent
  38  * password sniffing from HID devices.
  39  */
  40 #define EVENT_MAX  (4*PAGE_SIZE / sizeof(struct mon_event_text))
  41
  42 /*
  43  * Potentially unlimited number; we limit it for similar allocations.
  44  * The usbfs limits this to 128, but we're not quite as generous.
  45  */
  46 #define ISODESC_MAX   5
  47
  48 #define PRINTF_DFL  250   /* with 5 ISOs segs */
  49
  50 struct mon_iso_desc {
  51         int status;
  52         unsigned int offset;
  53         unsigned int length;    /* Unsigned here, signed in URB. Historic. */
  54 };
  55
  56 struct mon_event_text {
  57         struct list_head e_link;
  58         int type;               /* submit, complete, etc. */
  59         unsigned long id;       /* From pointer, most of the time */
  60         unsigned int tstamp;
  61         int busnum;
  62         char devnum;
  63         char epnum;
  64         char is_in;
  65         char xfertype;
  66         int length;             /* Depends on type: xfer length or act length */
  67         int status;
  68         int interval;
  69         int start_frame;
  70         int error_count;
  71         char setup_flag;
  72         char data_flag;
  73         int numdesc;            /* Full number */
  74         struct mon_iso_desc isodesc[ISODESC_MAX];
  75         unsigned char setup[SETUP_MAX];
  76         unsigned char data[DATA_MAX];
  77 };
  78
  79 #define SLAB_NAME_SZ  30
  80 struct mon_reader_text {
  81         struct kmem_cache *e_slab;
  82         int nevents;
  83         struct list_head e_list;
  84         struct mon_reader r;    /* In C, parent class can be placed anywhere */
  85
  86         wait_queue_head_t wait;
  87         int printf_size;
  88         char *printf_buf;
  89         struct mutex printf_lock;
  90
  91         char slab_name[SLAB_NAME_SZ];
  92 };
  93
  94 static struct dentry *mon_dir;          /* Usually /sys/kernel/debug/usbmon */
  95
  96 static void mon_text_ctor(void *);
  97
  98 struct mon_text_ptr {
  99         int cnt, limit;
 100         char *pbuf;
 101 };
 102
 103 static struct mon_event_text *
 104     mon_text_read_wait(struct mon_reader_text *rp, struct file *file);
 105 static void mon_text_read_head_t(struct mon_reader_text *rp,
 106         struct mon_text_ptr *p, const struct mon_event_text *ep);
 107 static void mon_text_read_head_u(struct mon_reader_text *rp,
 108         struct mon_text_ptr *p, const struct mon_event_text *ep);
 109 static void mon_text_read_statset(struct mon_reader_text *rp,
 110         struct mon_text_ptr *p, const struct mon_event_text *ep);
 111 static void mon_text_read_intstat(struct mon_reader_text *rp,
 112         struct mon_text_ptr *p, const struct mon_event_text *ep);
 113 static void mon_text_read_isostat(struct mon_reader_text *rp,
 114         struct mon_text_ptr *p, const struct mon_event_text *ep);
 115 static void mon_text_read_isodesc(struct mon_reader_text *rp,
 116         struct mon_text_ptr *p, const struct mon_event_text *ep);
 117 static void mon_text_read_data(struct mon_reader_text *rp,
 118     struct mon_text_ptr *p, const struct mon_event_text *ep);
 119
 120 /*
 121  * mon_text_submit
 122  * mon_text_complete
 123  *
 124  * May be called from an interrupt.
 125  *
 126  * This is called with the whole mon_bus locked, so no additional lock.
 127  */
 128
 129 static inline char mon_text_get_setup(struct mon_event_text *ep,
 130     struct urb *urb, char ev_type, struct mon_bus *mbus)
 131 {
 132
 133         if (ep->xfertype != USB_ENDPOINT_XFER_CONTROL || ev_type != 'S')
 134                 return '-';
 135
 136         if (urb->setup_packet == NULL)
 137                 return 'Z';     /* '0' would be not as pretty. */
 138
 139         memcpy(ep->setup, urb->setup_packet, SETUP_MAX);
 140         return 0;
 141 }
 142
 143 static inline char mon_text_get_data(struct mon_event_text *ep, struct urb *urb,
 144     int len, char ev_type, struct mon_bus *mbus)
 145 {
 146         void *src;
 147
 148         if (len <= 0)
 149                 return 'L';
 150         if (len >= DATA_MAX)
 151                 len = DATA_MAX;
 152
 153         if (ep->is_in) {
 154                 if (ev_type != 'C')
 155                         return '<';
 156         } else {
 157                 if (ev_type != 'S')
 158                         return '>';
 159         }
 160
 161         if (urb->num_sgs == 0) {
 162                 src = urb->transfer_buffer;
 163                 if (src == NULL)
 164                         return 'Z';     /* '0' would be not as pretty. */
 165         } else {
 166                 struct scatterlist *sg = urb->sg;
 167
 168                 if (PageHighMem(sg_page(sg)))
 169                         return 'D';
 170
 171                 /* For the text interface we copy only the first sg buffer */
 172                 len = min_t(int, sg->length, len);
 173                 src = sg_virt(sg);
 174         }
 175
 176         memcpy(ep->data, src, len);
 177         return 0;
 178 }
 179
 180 static inline unsigned int mon_get_timestamp(void)
 181 {
 182         struct timespec64 now;
 183         unsigned int stamp;
 184
 185         ktime_get_ts64(&now);
 186         stamp = now.tv_sec & 0xFFF;  /* 2^32 = 4294967296. Limit to 4096s. */
 187         stamp = stamp * USEC_PER_SEC + now.tv_nsec / NSEC_PER_USEC;
 188         return stamp;
 189 }
 190
 191 static void mon_text_event(struct mon_reader_text *rp, struct urb *urb,
 192     char ev_type, int status)
 193 {
 194         struct mon_event_text *ep;
 195         unsigned int stamp;
 196         struct usb_iso_packet_descriptor *fp;
 197         struct mon_iso_desc *dp;
 198         int i, ndesc;
 199
 200         stamp = mon_get_timestamp();
 201
 202         if (rp->nevents >= EVENT_MAX ||
 203             (ep = kmem_cache_alloc(rp->e_slab, GFP_ATOMIC)) == NULL) {
 204                 rp->r.m_bus->cnt_text_lost++;
 205                 return;
 206         }
 207
 208         ep->type = ev_type;
 209         ep->id = (unsigned long) urb;
 210         ep->busnum = urb->dev->bus->busnum;
 211         ep->devnum = urb->dev->devnum;
 212         ep->epnum = usb_endpoint_num(&urb->ep->desc);
 213         ep->xfertype = usb_endpoint_type(&urb->ep->desc);
 214         ep->is_in = usb_urb_dir_in(urb);
 215         ep->tstamp = stamp;
 216         ep->length = (ev_type == 'S') ?
 217             urb->transfer_buffer_length : urb->actual_length;
 218         /* Collecting status makes debugging sense for submits, too */
 219         ep->status = status;
 220
 221         if (ep->xfertype == USB_ENDPOINT_XFER_INT) {
 222                 ep->interval = urb->interval;
 223         } else if (ep->xfertype == USB_ENDPOINT_XFER_ISOC) {
 224                 ep->interval = urb->interval;
 225                 ep->start_frame = urb->start_frame;
 226                 ep->error_count = urb->error_count;
 227         }
 228         ep->numdesc = urb->number_of_packets;
 229         if (ep->xfertype == USB_ENDPOINT_XFER_ISOC &&
 230                         urb->number_of_packets > 0) {
 231                 if ((ndesc = urb->number_of_packets) > ISODESC_MAX)
 232                         ndesc = ISODESC_MAX;
 233                 fp = urb->iso_frame_desc;
 234                 dp = ep->isodesc;
 235                 for (i = 0; i < ndesc; i++) {
 236                         dp->status = fp->status;
 237                         dp->offset = fp->offset;
 238                         dp->length = (ev_type == 'S') ?
 239                             fp->length : fp->actual_length;
 240                         fp++;
 241                         dp++;
 242                 }
 243                 /* Wasteful, but simple to understand: ISO 'C' is sparse. */
 244                 if (ev_type == 'C')
 245                         ep->length = urb->transfer_buffer_length;
 246         }
 247
 248         ep->setup_flag = mon_text_get_setup(ep, urb, ev_type, rp->r.m_bus);
 249         ep->data_flag = mon_text_get_data(ep, urb, ep->length, ev_type,
 250                         rp->r.m_bus);
 251
 252         rp->nevents++;
 253         list_add_tail(&ep->e_link, &rp->e_list);
 254         wake_up(&rp->wait);
 255 }
 256
 257 static void mon_text_submit(void *data, struct urb *urb)
 258 {
 259         struct mon_reader_text *rp = data;
 260         mon_text_event(rp, urb, 'S', -EINPROGRESS);
 261 }
 262
 263 static void mon_text_complete(void *data, struct urb *urb, int status)
 264 {
 265         struct mon_reader_text *rp = data;
 266         mon_text_event(rp, urb, 'C', status);
 267 }
 268
 269 static void mon_text_error(void *data, struct urb *urb, int error)
 270 {
 271         struct mon_reader_text *rp = data;
 272         struct mon_event_text *ep;
 273
 274         if (rp->nevents >= EVENT_MAX ||
 275             (ep = kmem_cache_alloc(rp->e_slab, GFP_ATOMIC)) == NULL) {
 276                 rp->r.m_bus->cnt_text_lost++;
 277                 return;
 278         }
 279
 280         ep->type = 'E';
 281         ep->id = (unsigned long) urb;
 282         ep->busnum = urb->dev->bus->busnum;
 283         ep->devnum = urb->dev->devnum;
 284         ep->epnum = usb_endpoint_num(&urb->ep->desc);
 285         ep->xfertype = usb_endpoint_type(&urb->ep->desc);
 286         ep->is_in = usb_urb_dir_in(urb);
 287         ep->tstamp = mon_get_timestamp();
 288         ep->length = 0;
 289         ep->status = error;
 290
 291         ep->setup_flag = '-';
 292         ep->data_flag = 'E';
 293
 294         rp->nevents++;
 295         list_add_tail(&ep->e_link, &rp->e_list);
 296         wake_up(&rp->wait);
 297 }
 298
 299 /*
 300  * Fetch next event from the circular buffer.
 301  */
 302 static struct mon_event_text *mon_text_fetch(struct mon_reader_text *rp,
 303     struct mon_bus *mbus)
 304 {
 305         struct list_head *p;
 306         unsigned long flags;
 307
 308         spin_lock_irqsave(&mbus->lock, flags);
 309         if (list_empty(&rp->e_list)) {
 310                 spin_unlock_irqrestore(&mbus->lock, flags);
 311                 return NULL;
 312         }
 313         p = rp->e_list.next;
 314         list_del(p);
 315         --rp->nevents;
 316         spin_unlock_irqrestore(&mbus->lock, flags);
 317         return list_entry(p, struct mon_event_text, e_link);
 318 }
 319
 320 /*
 321  */
 322 static int mon_text_open(struct inode *inode, struct file *file)
 323 {
 324         struct mon_bus *mbus;
 325         struct mon_reader_text *rp;
 326         int rc;
 327
 328         mutex_lock(&mon_lock);
 329         mbus = inode->i_private;
 330
 331         rp = kzalloc(sizeof(struct mon_reader_text), GFP_KERNEL);
 332         if (rp == NULL) {
 333                 rc = -ENOMEM;
 334                 goto err_alloc;
 335         }
 336         INIT_LIST_HEAD(&rp->e_list);
 337         init_waitqueue_head(&rp->wait);
 338         mutex_init(&rp->printf_lock);
 339
 340         rp->printf_size = PRINTF_DFL;
 341         rp->printf_buf = kmalloc(rp->printf_size, GFP_KERNEL);
 342         if (rp->printf_buf == NULL) {
 343                 rc = -ENOMEM;
 344                 goto err_alloc_pr;
 345         }
 346
 347         rp->r.m_bus = mbus;
 348         rp->r.r_data = rp;
 349         rp->r.rnf_submit = mon_text_submit;
 350         rp->r.rnf_error = mon_text_error;
 351         rp->r.rnf_complete = mon_text_complete;
 352
 353         snprintf(rp->slab_name, SLAB_NAME_SZ, "mon_text_%p", rp);
 354         rp->e_slab = kmem_cache_create(rp->slab_name,
 355             sizeof(struct mon_event_text), sizeof(long), 0,
 356             mon_text_ctor);
 357         if (rp->e_slab == NULL) {
 358                 rc = -ENOMEM;
 359                 goto err_slab;
 360         }
 361
 362         mon_reader_add(mbus, &rp->r);
 363
 364         file->private_data = rp;
 365         mutex_unlock(&mon_lock);
 366         return 0;
 367
 368 // err_busy:
 369 //      kmem_cache_destroy(rp->e_slab);
 370 err_slab:
 371         kfree(rp->printf_buf);
 372 err_alloc_pr:
 373         kfree(rp);
 374 err_alloc:
 375         mutex_unlock(&mon_lock);
 376         return rc;
 377 }
 378
 379 /*
 380  * For simplicity, we read one record in one system call and throw out
 381  * what does not fit. This means that the following does not work:
 382  *   dd if=/dbg/usbmon/0t bs=10
 383  * Also, we do not allow seeks and do not bother advancing the offset.
 384  */
 385 static ssize_t mon_text_read_t(struct file *file, char __user *buf,
 386                                 size_t nbytes, loff_t *ppos)
 387 {
 388         struct mon_reader_text *rp = file->private_data;
 389         struct mon_event_text *ep;
 390         struct mon_text_ptr ptr;
 391
 392         ep = mon_text_read_wait(rp, file);
 393         if (IS_ERR(ep))
 394                 return PTR_ERR(ep);
 395         mutex_lock(&rp->printf_lock);
 396         ptr.cnt = 0;
 397         ptr.pbuf = rp->printf_buf;
 398         ptr.limit = rp->printf_size;
 399
 400         mon_text_read_head_t(rp, &ptr, ep);
 401         mon_text_read_statset(rp, &ptr, ep);
 402         ptr.cnt += snprintf(ptr.pbuf + ptr.cnt, ptr.limit - ptr.cnt,
 403             " %d", ep->length);
 404         mon_text_read_data(rp, &ptr, ep);
 405
 406         if (copy_to_user(buf, rp->printf_buf, ptr.cnt))
 407                 ptr.cnt = -EFAULT;
 408         mutex_unlock(&rp->printf_lock);
 409         kmem_cache_free(rp->e_slab, ep);
 410         return ptr.cnt;
 411 }
 412
 413 static ssize_t mon_text_read_u(struct file *file, char __user *buf,
 414                                 size_t nbytes, loff_t *ppos)
 415 {
 416         struct mon_reader_text *rp = file->private_data;
 417         struct mon_event_text *ep;
 418         struct mon_text_ptr ptr;
 419
 420         ep = mon_text_read_wait(rp, file);
 421         if (IS_ERR(ep))
 422                 return PTR_ERR(ep);
 423         mutex_lock(&rp->printf_lock);
 424         ptr.cnt = 0;
 425         ptr.pbuf = rp->printf_buf;
 426         ptr.limit = rp->printf_size;
 427
 428         mon_text_read_head_u(rp, &ptr, ep);
 429         if (ep->type == 'E') {
 430                 mon_text_read_statset(rp, &ptr, ep);
 431         } else if (ep->xfertype == USB_ENDPOINT_XFER_ISOC) {
 432                 mon_text_read_isostat(rp, &ptr, ep);
 433                 mon_text_read_isodesc(rp, &ptr, ep);
 434         } else if (ep->xfertype == USB_ENDPOINT_XFER_INT) {
 435                 mon_text_read_intstat(rp, &ptr, ep);
 436         } else {
 437                 mon_text_read_statset(rp, &ptr, ep);
 438         }
 439         ptr.cnt += snprintf(ptr.pbuf + ptr.cnt, ptr.limit - ptr.cnt,
 440             " %d", ep->length);
 441         mon_text_read_data(rp, &ptr, ep);
 442
 443         if (copy_to_user(buf, rp->printf_buf, ptr.cnt))
 444                 ptr.cnt = -EFAULT;
 445         mutex_unlock(&rp->printf_lock);
 446         kmem_cache_free(rp->e_slab, ep);
 447         return ptr.cnt;
 448 }
 449
 450 static struct mon_event_text *mon_text_read_wait(struct mon_reader_text *rp,
 451     struct file *file)
 452 {
 453         struct mon_bus *mbus = rp->r.m_bus;
 454         DECLARE_WAITQUEUE(waita, current);
 455         struct mon_event_text *ep;
 456
 457         add_wait_queue(&rp->wait, &waita);
 458         set_current_state(TASK_INTERRUPTIBLE);
 459         while ((ep = mon_text_fetch(rp, mbus)) == NULL) {
 460                 if (file->f_flags & O_NONBLOCK) {
 461                         set_current_state(TASK_RUNNING);
 462                         remove_wait_queue(&rp->wait, &waita);
 463                         return ERR_PTR(-EWOULDBLOCK);
 464                 }
 465                 /*
 466                  * We do not count nwaiters, because ->release is supposed
 467                  * to be called when all openers are gone only.
 468                  */
 469                 schedule();
 470                 if (signal_pending(current)) {
 471                         remove_wait_queue(&rp->wait, &waita);
 472                         return ERR_PTR(-EINTR);
 473                 }
 474                 set_current_state(TASK_INTERRUPTIBLE);
 475         }
 476         set_current_state(TASK_RUNNING);
 477         remove_wait_queue(&rp->wait, &waita);
 478         return ep;
 479 }
 480
 481 static void mon_text_read_head_t(struct mon_reader_text *rp,
 482         struct mon_text_ptr *p, const struct mon_event_text *ep)
 483 {
 484         char udir, utype;
 485
 486         udir = (ep->is_in ? 'i' : 'o');
 487         switch (ep->xfertype) {
 488         case USB_ENDPOINT_XFER_ISOC:    utype = 'Z'; break;
 489         case USB_ENDPOINT_XFER_INT:     utype = 'I'; break;
 490         case USB_ENDPOINT_XFER_CONTROL: utype = 'C'; break;
 491         default: /* PIPE_BULK */  utype = 'B';
 492         }
 493         p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 494             "%lx %u %c %c%c:%03u:%02u",
 495             ep->id, ep->tstamp, ep->type,
 496             utype, udir, ep->devnum, ep->epnum);
 497 }
 498
 499 static void mon_text_read_head_u(struct mon_reader_text *rp,
 500         struct mon_text_ptr *p, const struct mon_event_text *ep)
 501 {
 502         char udir, utype;
 503
 504         udir = (ep->is_in ? 'i' : 'o');
 505         switch (ep->xfertype) {
 506         case USB_ENDPOINT_XFER_ISOC:    utype = 'Z'; break;
 507         case USB_ENDPOINT_XFER_INT:     utype = 'I'; break;
 508         case USB_ENDPOINT_XFER_CONTROL: utype = 'C'; break;
 509         default: /* PIPE_BULK */  utype = 'B';
 510         }
 511         p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 512             "%lx %u %c %c%c:%d:%03u:%u",
 513             ep->id, ep->tstamp, ep->type,
 514             utype, udir, ep->busnum, ep->devnum, ep->epnum);
 515 }
 516
 517 static void mon_text_read_statset(struct mon_reader_text *rp,
 518         struct mon_text_ptr *p, const struct mon_event_text *ep)
 519 {
 520
 521         if (ep->setup_flag == 0) {   /* Setup packet is present and captured */
 522                 p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 523                     " s %02x %02x %04x %04x %04x",
 524                     ep->setup[0],
 525                     ep->setup[1],
 526                     (ep->setup[3] << 8) | ep->setup[2],
 527                     (ep->setup[5] << 8) | ep->setup[4],
 528                     (ep->setup[7] << 8) | ep->setup[6]);
 529         } else if (ep->setup_flag != '-') { /* Unable to capture setup packet */
 530                 p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 531                     " %c __ __ ____ ____ ____", ep->setup_flag);
 532         } else {                     /* No setup for this kind of URB */
 533                 p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 534                     " %d", ep->status);
 535         }
 536 }
 537
 538 static void mon_text_read_intstat(struct mon_reader_text *rp,
 539         struct mon_text_ptr *p, const struct mon_event_text *ep)
 540 {
 541         p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 542             " %d:%d", ep->status, ep->interval);
 543 }
 544
 545 static void mon_text_read_isostat(struct mon_reader_text *rp,
 546         struct mon_text_ptr *p, const struct mon_event_text *ep)
 547 {
 548         if (ep->type == 'S') {
 549                 p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 550                     " %d:%d:%d", ep->status, ep->interval, ep->start_frame);
 551         } else {
 552                 p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 553                     " %d:%d:%d:%d",
 554                     ep->status, ep->interval, ep->start_frame, ep->error_count);
 555         }
 556 }
 557
 558 static void mon_text_read_isodesc(struct mon_reader_text *rp,
 559         struct mon_text_ptr *p, const struct mon_event_text *ep)
 560 {
 561         int ndesc;      /* Display this many */
 562         int i;
 563         const struct mon_iso_desc *dp;
 564
 565         p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 566             " %d", ep->numdesc);
 567         ndesc = ep->numdesc;
 568         if (ndesc > ISODESC_MAX)
 569                 ndesc = ISODESC_MAX;
 570         if (ndesc < 0)
 571                 ndesc = 0;
 572         dp = ep->isodesc;
 573         for (i = 0; i < ndesc; i++) {
 574                 p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 575                     " %d:%u:%u", dp->status, dp->offset, dp->length);
 576                 dp++;
 577         }
 578 }
 579
 580 static void mon_text_read_data(struct mon_reader_text *rp,
 581     struct mon_text_ptr *p, const struct mon_event_text *ep)
 582 {
 583         int data_len, i;
 584
 585         if ((data_len = ep->length) > 0) {
 586                 if (ep->data_flag == 0) {
 587                         p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 588                             " =");
 589                         if (data_len >= DATA_MAX)
 590                                 data_len = DATA_MAX;
 591                         for (i = 0; i < data_len; i++) {
 592                                 if (i % 4 == 0) {
 593                                         p->cnt += snprintf(p->pbuf + p->cnt,
 594                                             p->limit - p->cnt,
 595                                             " ");
 596                                 }
 597                                 p->cnt += snprintf(p->pbuf + p->cnt,
 598                                     p->limit - p->cnt,
 599                                     "%02x", ep->data[i]);
 600                         }
 601                         p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 602                             "\n");
 603                 } else {
 604                         p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 605                             " %c\n", ep->data_flag);
 606                 }
 607         } else {
 608                 p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt, "\n");
 609         }
 610 }
 611
 612 static int mon_text_release(struct inode *inode, struct file *file)
 613 {
 614         struct mon_reader_text *rp = file->private_data;
 615         struct mon_bus *mbus;
 616         /* unsigned long flags; */
 617         struct list_head *p;
 618         struct mon_event_text *ep;
 619
 620         mutex_lock(&mon_lock);
 621         mbus = inode->i_private;
 622
 623         if (mbus->nreaders <= 0) {
 624                 printk(KERN_ERR TAG ": consistency error on close\n");
 625                 mutex_unlock(&mon_lock);
 626                 return 0;
 627         }
 628         mon_reader_del(mbus, &rp->r);
 629
 630         /*
 631          * In theory, e_list is protected by mbus->lock. However,
 632          * after mon_reader_del has finished, the following is the case:
 633          *  - we are not on reader list anymore, so new events won't be added;
 634          *  - whole mbus may be dropped if it was orphaned.
 635          * So, we better not touch mbus.
 636          */
 637         /* spin_lock_irqsave(&mbus->lock, flags); */
 638         while (!list_empty(&rp->e_list)) {
 639                 p = rp->e_list.next;
 640                 ep = list_entry(p, struct mon_event_text, e_link);
 641                 list_del(p);
 642                 --rp->nevents;
 643                 kmem_cache_free(rp->e_slab, ep);
 644         }
 645         /* spin_unlock_irqrestore(&mbus->lock, flags); */
 646
 647         kmem_cache_destroy(rp->e_slab);
 648         kfree(rp->printf_buf);
 649         kfree(rp);
 650
 651         mutex_unlock(&mon_lock);
 652         return 0;
 653 }
 654
 655 static const struct file_operations mon_fops_text_t = {
 656         .owner =        THIS_MODULE,
 657         .open =         mon_text_open,
 658         .llseek =       no_llseek,
 659         .read =         mon_text_read_t,
 660         .release =      mon_text_release,
 661 };
 662
 663 static const struct file_operations mon_fops_text_u = {
 664         .owner =        THIS_MODULE,
 665         .open =         mon_text_open,
 666         .llseek =       no_llseek,
 667         .read =         mon_text_read_u,
 668         .release =      mon_text_release,
 669 };
 670
 671 int mon_text_add(struct mon_bus *mbus, const struct usb_bus *ubus)
 672 {
 673         struct dentry *d;
 674         enum { NAMESZ = 10 };
 675         char name[NAMESZ];
 676         int busnum = ubus? ubus->busnum: 0;
 677         int rc;
 678
 679         if (mon_dir == NULL)
 680                 return 0;
 681
 682         if (ubus != NULL) {
 683                 rc = snprintf(name, NAMESZ, "%dt", busnum);
 684                 if (rc <= 0 || rc >= NAMESZ)
 685                         goto err_print_t;
 686                 d = debugfs_create_file(name, 0600, mon_dir, mbus,
 687                                                              &mon_fops_text_t);
 688                 if (d == NULL)
 689                         goto err_create_t;
 690                 mbus->dent_t = d;
 691         }
 692
 693         rc = snprintf(name, NAMESZ, "%du", busnum);
 694         if (rc <= 0 || rc >= NAMESZ)
 695                 goto err_print_u;
 696         d = debugfs_create_file(name, 0600, mon_dir, mbus, &mon_fops_text_u);
 697         if (d == NULL)
 698                 goto err_create_u;
 699         mbus->dent_u = d;
 700
 701         rc = snprintf(name, NAMESZ, "%ds", busnum);
 702         if (rc <= 0 || rc >= NAMESZ)
 703                 goto err_print_s;
 704         d = debugfs_create_file(name, 0600, mon_dir, mbus, &mon_fops_stat);
 705         if (d == NULL)
 706                 goto err_create_s;
 707         mbus->dent_s = d;
 708
 709         return 1;
 710
 711 err_create_s:
 712 err_print_s:
 713         debugfs_remove(mbus->dent_u);
 714         mbus->dent_u = NULL;
 715 err_create_u:
 716 err_print_u:
 717         if (ubus != NULL) {
 718                 debugfs_remove(mbus->dent_t);
 719                 mbus->dent_t = NULL;
 720         }
 721 err_create_t:
 722 err_print_t:
 723         return 0;
 724 }
 725
 726 void mon_text_del(struct mon_bus *mbus)
 727 {
 728         debugfs_remove(mbus->dent_u);
 729         if (mbus->dent_t != NULL)
 730                 debugfs_remove(mbus->dent_t);
 731         debugfs_remove(mbus->dent_s);
 732 }
 733
 734 /*
 735  * Slab interface: constructor.
 736  */
 737 static void mon_text_ctor(void *mem)
 738 {
 739         /*
 740          * Nothing to initialize. No, really!
 741          * So, we fill it with garbage to emulate a reused object.
 742          */
 743         memset(mem, 0xe5, sizeof(struct mon_event_text));
 744 }
 745
 746 int __init mon_text_init(void)
 747 {
 748         struct dentry *mondir;
 749
 750         mondir = debugfs_create_dir("usbmon", usb_debug_root);
 751         if (IS_ERR(mondir)) {
 752                 /* debugfs not available, but we can use usbmon without it */
 753                 return 0;
 754         }
 755         if (mondir == NULL) {
 756                 printk(KERN_NOTICE TAG ": unable to create usbmon directory\n");
 757                 return -ENOMEM;
 758         }
 759         mon_dir = mondir;
 760         return 0;
 761 }
 762
 763 void mon_text_exit(void)
 764 {
 765         debugfs_remove(mon_dir);
 766 }