linux/drivers/usb/mon/mon_text.c
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   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
  50struct mon_iso_desc {
  51        int status;
  52        unsigned int offset;
  53        unsigned int length;    /* Unsigned here, signed in URB. Historic. */
  54};
  55
  56struct 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
  80struct 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        size_t printf_offset;
  89        size_t printf_togo;
  90        char *printf_buf;
  91        struct mutex printf_lock;
  92
  93        char slab_name[SLAB_NAME_SZ];
  94};
  95
  96static struct dentry *mon_dir;          /* Usually /sys/kernel/debug/usbmon */
  97
  98static void mon_text_ctor(void *);
  99
 100struct mon_text_ptr {
 101        int cnt, limit;
 102        char *pbuf;
 103};
 104
 105static struct mon_event_text *
 106    mon_text_read_wait(struct mon_reader_text *rp, struct file *file);
 107static void mon_text_read_head_t(struct mon_reader_text *rp,
 108        struct mon_text_ptr *p, const struct mon_event_text *ep);
 109static void mon_text_read_head_u(struct mon_reader_text *rp,
 110        struct mon_text_ptr *p, const struct mon_event_text *ep);
 111static void mon_text_read_statset(struct mon_reader_text *rp,
 112        struct mon_text_ptr *p, const struct mon_event_text *ep);
 113static void mon_text_read_intstat(struct mon_reader_text *rp,
 114        struct mon_text_ptr *p, const struct mon_event_text *ep);
 115static void mon_text_read_isostat(struct mon_reader_text *rp,
 116        struct mon_text_ptr *p, const struct mon_event_text *ep);
 117static void mon_text_read_isodesc(struct mon_reader_text *rp,
 118        struct mon_text_ptr *p, const struct mon_event_text *ep);
 119static void mon_text_read_data(struct mon_reader_text *rp,
 120    struct mon_text_ptr *p, const struct mon_event_text *ep);
 121
 122/*
 123 * mon_text_submit
 124 * mon_text_complete
 125 *
 126 * May be called from an interrupt.
 127 *
 128 * This is called with the whole mon_bus locked, so no additional lock.
 129 */
 130
 131static inline char mon_text_get_setup(struct mon_event_text *ep,
 132    struct urb *urb, char ev_type, struct mon_bus *mbus)
 133{
 134
 135        if (ep->xfertype != USB_ENDPOINT_XFER_CONTROL || ev_type != 'S')
 136                return '-';
 137
 138        if (urb->setup_packet == NULL)
 139                return 'Z';     /* '0' would be not as pretty. */
 140
 141        memcpy(ep->setup, urb->setup_packet, SETUP_MAX);
 142        return 0;
 143}
 144
 145static inline char mon_text_get_data(struct mon_event_text *ep, struct urb *urb,
 146    int len, char ev_type, struct mon_bus *mbus)
 147{
 148        void *src;
 149
 150        if (len <= 0)
 151                return 'L';
 152        if (len >= DATA_MAX)
 153                len = DATA_MAX;
 154
 155        if (ep->is_in) {
 156                if (ev_type != 'C')
 157                        return '<';
 158        } else {
 159                if (ev_type != 'S')
 160                        return '>';
 161        }
 162
 163        if (urb->num_sgs == 0) {
 164                src = urb->transfer_buffer;
 165                if (src == NULL)
 166                        return 'Z';     /* '0' would be not as pretty. */
 167        } else {
 168                struct scatterlist *sg = urb->sg;
 169
 170                if (PageHighMem(sg_page(sg)))
 171                        return 'D';
 172
 173                /* For the text interface we copy only the first sg buffer */
 174                len = min_t(int, sg->length, len);
 175                src = sg_virt(sg);
 176        }
 177
 178        memcpy(ep->data, src, len);
 179        return 0;
 180}
 181
 182static inline unsigned int mon_get_timestamp(void)
 183{
 184        struct timespec64 now;
 185        unsigned int stamp;
 186
 187        ktime_get_ts64(&now);
 188        stamp = now.tv_sec & 0xFFF;  /* 2^32 = 4294967296. Limit to 4096s. */
 189        stamp = stamp * USEC_PER_SEC + now.tv_nsec / NSEC_PER_USEC;
 190        return stamp;
 191}
 192
 193static void mon_text_event(struct mon_reader_text *rp, struct urb *urb,
 194    char ev_type, int status)
 195{
 196        struct mon_event_text *ep;
 197        unsigned int stamp;
 198        struct usb_iso_packet_descriptor *fp;
 199        struct mon_iso_desc *dp;
 200        int i, ndesc;
 201
 202        stamp = mon_get_timestamp();
 203
 204        if (rp->nevents >= EVENT_MAX ||
 205            (ep = kmem_cache_alloc(rp->e_slab, GFP_ATOMIC)) == NULL) {
 206                rp->r.m_bus->cnt_text_lost++;
 207                return;
 208        }
 209
 210        ep->type = ev_type;
 211        ep->id = (unsigned long) urb;
 212        ep->busnum = urb->dev->bus->busnum;
 213        ep->devnum = urb->dev->devnum;
 214        ep->epnum = usb_endpoint_num(&urb->ep->desc);
 215        ep->xfertype = usb_endpoint_type(&urb->ep->desc);
 216        ep->is_in = usb_urb_dir_in(urb);
 217        ep->tstamp = stamp;
 218        ep->length = (ev_type == 'S') ?
 219            urb->transfer_buffer_length : urb->actual_length;
 220        /* Collecting status makes debugging sense for submits, too */
 221        ep->status = status;
 222
 223        if (ep->xfertype == USB_ENDPOINT_XFER_INT) {
 224                ep->interval = urb->interval;
 225        } else if (ep->xfertype == USB_ENDPOINT_XFER_ISOC) {
 226                ep->interval = urb->interval;
 227                ep->start_frame = urb->start_frame;
 228                ep->error_count = urb->error_count;
 229        }
 230        ep->numdesc = urb->number_of_packets;
 231        if (ep->xfertype == USB_ENDPOINT_XFER_ISOC &&
 232                        urb->number_of_packets > 0) {
 233                if ((ndesc = urb->number_of_packets) > ISODESC_MAX)
 234                        ndesc = ISODESC_MAX;
 235                fp = urb->iso_frame_desc;
 236                dp = ep->isodesc;
 237                for (i = 0; i < ndesc; i++) {
 238                        dp->status = fp->status;
 239                        dp->offset = fp->offset;
 240                        dp->length = (ev_type == 'S') ?
 241                            fp->length : fp->actual_length;
 242                        fp++;
 243                        dp++;
 244                }
 245                /* Wasteful, but simple to understand: ISO 'C' is sparse. */
 246                if (ev_type == 'C')
 247                        ep->length = urb->transfer_buffer_length;
 248        }
 249
 250        ep->setup_flag = mon_text_get_setup(ep, urb, ev_type, rp->r.m_bus);
 251        ep->data_flag = mon_text_get_data(ep, urb, ep->length, ev_type,
 252                        rp->r.m_bus);
 253
 254        rp->nevents++;
 255        list_add_tail(&ep->e_link, &rp->e_list);
 256        wake_up(&rp->wait);
 257}
 258
 259static void mon_text_submit(void *data, struct urb *urb)
 260{
 261        struct mon_reader_text *rp = data;
 262        mon_text_event(rp, urb, 'S', -EINPROGRESS);
 263}
 264
 265static void mon_text_complete(void *data, struct urb *urb, int status)
 266{
 267        struct mon_reader_text *rp = data;
 268        mon_text_event(rp, urb, 'C', status);
 269}
 270
 271static void mon_text_error(void *data, struct urb *urb, int error)
 272{
 273        struct mon_reader_text *rp = data;
 274        struct mon_event_text *ep;
 275
 276        if (rp->nevents >= EVENT_MAX ||
 277            (ep = kmem_cache_alloc(rp->e_slab, GFP_ATOMIC)) == NULL) {
 278                rp->r.m_bus->cnt_text_lost++;
 279                return;
 280        }
 281
 282        ep->type = 'E';
 283        ep->id = (unsigned long) urb;
 284        ep->busnum = urb->dev->bus->busnum;
 285        ep->devnum = urb->dev->devnum;
 286        ep->epnum = usb_endpoint_num(&urb->ep->desc);
 287        ep->xfertype = usb_endpoint_type(&urb->ep->desc);
 288        ep->is_in = usb_urb_dir_in(urb);
 289        ep->tstamp = mon_get_timestamp();
 290        ep->length = 0;
 291        ep->status = error;
 292
 293        ep->setup_flag = '-';
 294        ep->data_flag = 'E';
 295
 296        rp->nevents++;
 297        list_add_tail(&ep->e_link, &rp->e_list);
 298        wake_up(&rp->wait);
 299}
 300
 301/*
 302 * Fetch next event from the circular buffer.
 303 */
 304static struct mon_event_text *mon_text_fetch(struct mon_reader_text *rp,
 305    struct mon_bus *mbus)
 306{
 307        struct list_head *p;
 308        unsigned long flags;
 309
 310        spin_lock_irqsave(&mbus->lock, flags);
 311        if (list_empty(&rp->e_list)) {
 312                spin_unlock_irqrestore(&mbus->lock, flags);
 313                return NULL;
 314        }
 315        p = rp->e_list.next;
 316        list_del(p);
 317        --rp->nevents;
 318        spin_unlock_irqrestore(&mbus->lock, flags);
 319        return list_entry(p, struct mon_event_text, e_link);
 320}
 321
 322/*
 323 */
 324static int mon_text_open(struct inode *inode, struct file *file)
 325{
 326        struct mon_bus *mbus;
 327        struct mon_reader_text *rp;
 328        int rc;
 329
 330        mutex_lock(&mon_lock);
 331        mbus = inode->i_private;
 332
 333        rp = kzalloc(sizeof(struct mon_reader_text), GFP_KERNEL);
 334        if (rp == NULL) {
 335                rc = -ENOMEM;
 336                goto err_alloc;
 337        }
 338        INIT_LIST_HEAD(&rp->e_list);
 339        init_waitqueue_head(&rp->wait);
 340        mutex_init(&rp->printf_lock);
 341
 342        rp->printf_size = PRINTF_DFL;
 343        rp->printf_buf = kmalloc(rp->printf_size, GFP_KERNEL);
 344        if (rp->printf_buf == NULL) {
 345                rc = -ENOMEM;
 346                goto err_alloc_pr;
 347        }
 348
 349        rp->r.m_bus = mbus;
 350        rp->r.r_data = rp;
 351        rp->r.rnf_submit = mon_text_submit;
 352        rp->r.rnf_error = mon_text_error;
 353        rp->r.rnf_complete = mon_text_complete;
 354
 355        snprintf(rp->slab_name, SLAB_NAME_SZ, "mon_text_%p", rp);
 356        rp->e_slab = kmem_cache_create(rp->slab_name,
 357            sizeof(struct mon_event_text), sizeof(long), 0,
 358            mon_text_ctor);
 359        if (rp->e_slab == NULL) {
 360                rc = -ENOMEM;
 361                goto err_slab;
 362        }
 363
 364        mon_reader_add(mbus, &rp->r);
 365
 366        file->private_data = rp;
 367        mutex_unlock(&mon_lock);
 368        return 0;
 369
 370// err_busy:
 371//      kmem_cache_destroy(rp->e_slab);
 372err_slab:
 373        kfree(rp->printf_buf);
 374err_alloc_pr:
 375        kfree(rp);
 376err_alloc:
 377        mutex_unlock(&mon_lock);
 378        return rc;
 379}
 380
 381static ssize_t mon_text_copy_to_user(struct mon_reader_text *rp,
 382    char __user * const buf, const size_t nbytes)
 383{
 384        const size_t togo = min(nbytes, rp->printf_togo);
 385
 386        if (copy_to_user(buf, &rp->printf_buf[rp->printf_offset], togo))
 387                return -EFAULT;
 388        rp->printf_togo -= togo;
 389        rp->printf_offset += togo;
 390        return togo;
 391}
 392
 393/* ppos is not advanced since the llseek operation is not permitted. */
 394static ssize_t mon_text_read_t(struct file *file, char __user *buf,
 395    size_t nbytes, loff_t *ppos)
 396{
 397        struct mon_reader_text *rp = file->private_data;
 398        struct mon_event_text *ep;
 399        struct mon_text_ptr ptr;
 400        ssize_t ret;
 401
 402        mutex_lock(&rp->printf_lock);
 403
 404        if (rp->printf_togo == 0) {
 405
 406                ep = mon_text_read_wait(rp, file);
 407                if (IS_ERR(ep)) {
 408                        mutex_unlock(&rp->printf_lock);
 409                        return PTR_ERR(ep);
 410                }
 411                ptr.cnt = 0;
 412                ptr.pbuf = rp->printf_buf;
 413                ptr.limit = rp->printf_size;
 414
 415                mon_text_read_head_t(rp, &ptr, ep);
 416                mon_text_read_statset(rp, &ptr, ep);
 417                ptr.cnt += snprintf(ptr.pbuf + ptr.cnt, ptr.limit - ptr.cnt,
 418                    " %d", ep->length);
 419                mon_text_read_data(rp, &ptr, ep);
 420
 421                rp->printf_togo = ptr.cnt;
 422                rp->printf_offset = 0;
 423
 424                kmem_cache_free(rp->e_slab, ep);
 425        }
 426
 427        ret = mon_text_copy_to_user(rp, buf, nbytes);
 428        mutex_unlock(&rp->printf_lock);
 429        return ret;
 430}
 431
 432/* ppos is not advanced since the llseek operation is not permitted. */
 433static ssize_t mon_text_read_u(struct file *file, char __user *buf,
 434    size_t nbytes, loff_t *ppos)
 435{
 436        struct mon_reader_text *rp = file->private_data;
 437        struct mon_event_text *ep;
 438        struct mon_text_ptr ptr;
 439        ssize_t ret;
 440
 441        mutex_lock(&rp->printf_lock);
 442
 443        if (rp->printf_togo == 0) {
 444
 445                ep = mon_text_read_wait(rp, file);
 446                if (IS_ERR(ep)) {
 447                        mutex_unlock(&rp->printf_lock);
 448                        return PTR_ERR(ep);
 449                }
 450                ptr.cnt = 0;
 451                ptr.pbuf = rp->printf_buf;
 452                ptr.limit = rp->printf_size;
 453
 454                mon_text_read_head_u(rp, &ptr, ep);
 455                if (ep->type == 'E') {
 456                        mon_text_read_statset(rp, &ptr, ep);
 457                } else if (ep->xfertype == USB_ENDPOINT_XFER_ISOC) {
 458                        mon_text_read_isostat(rp, &ptr, ep);
 459                        mon_text_read_isodesc(rp, &ptr, ep);
 460                } else if (ep->xfertype == USB_ENDPOINT_XFER_INT) {
 461                        mon_text_read_intstat(rp, &ptr, ep);
 462                } else {
 463                        mon_text_read_statset(rp, &ptr, ep);
 464                }
 465                ptr.cnt += snprintf(ptr.pbuf + ptr.cnt, ptr.limit - ptr.cnt,
 466                    " %d", ep->length);
 467                mon_text_read_data(rp, &ptr, ep);
 468
 469                rp->printf_togo = ptr.cnt;
 470                rp->printf_offset = 0;
 471
 472                kmem_cache_free(rp->e_slab, ep);
 473        }
 474
 475        ret = mon_text_copy_to_user(rp, buf, nbytes);
 476        mutex_unlock(&rp->printf_lock);
 477        return ret;
 478}
 479
 480static struct mon_event_text *mon_text_read_wait(struct mon_reader_text *rp,
 481    struct file *file)
 482{
 483        struct mon_bus *mbus = rp->r.m_bus;
 484        DECLARE_WAITQUEUE(waita, current);
 485        struct mon_event_text *ep;
 486
 487        add_wait_queue(&rp->wait, &waita);
 488        set_current_state(TASK_INTERRUPTIBLE);
 489        while ((ep = mon_text_fetch(rp, mbus)) == NULL) {
 490                if (file->f_flags & O_NONBLOCK) {
 491                        set_current_state(TASK_RUNNING);
 492                        remove_wait_queue(&rp->wait, &waita);
 493                        return ERR_PTR(-EWOULDBLOCK);
 494                }
 495                /*
 496                 * We do not count nwaiters, because ->release is supposed
 497                 * to be called when all openers are gone only.
 498                 */
 499                schedule();
 500                if (signal_pending(current)) {
 501                        remove_wait_queue(&rp->wait, &waita);
 502                        return ERR_PTR(-EINTR);
 503                }
 504                set_current_state(TASK_INTERRUPTIBLE);
 505        }
 506        set_current_state(TASK_RUNNING);
 507        remove_wait_queue(&rp->wait, &waita);
 508        return ep;
 509}
 510
 511static void mon_text_read_head_t(struct mon_reader_text *rp,
 512        struct mon_text_ptr *p, const struct mon_event_text *ep)
 513{
 514        char udir, utype;
 515
 516        udir = (ep->is_in ? 'i' : 'o');
 517        switch (ep->xfertype) {
 518        case USB_ENDPOINT_XFER_ISOC:    utype = 'Z'; break;
 519        case USB_ENDPOINT_XFER_INT:     utype = 'I'; break;
 520        case USB_ENDPOINT_XFER_CONTROL: utype = 'C'; break;
 521        default: /* PIPE_BULK */  utype = 'B';
 522        }
 523        p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 524            "%lx %u %c %c%c:%03u:%02u",
 525            ep->id, ep->tstamp, ep->type,
 526            utype, udir, ep->devnum, ep->epnum);
 527}
 528
 529static void mon_text_read_head_u(struct mon_reader_text *rp,
 530        struct mon_text_ptr *p, const struct mon_event_text *ep)
 531{
 532        char udir, utype;
 533
 534        udir = (ep->is_in ? 'i' : 'o');
 535        switch (ep->xfertype) {
 536        case USB_ENDPOINT_XFER_ISOC:    utype = 'Z'; break;
 537        case USB_ENDPOINT_XFER_INT:     utype = 'I'; break;
 538        case USB_ENDPOINT_XFER_CONTROL: utype = 'C'; break;
 539        default: /* PIPE_BULK */  utype = 'B';
 540        }
 541        p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 542            "%lx %u %c %c%c:%d:%03u:%u",
 543            ep->id, ep->tstamp, ep->type,
 544            utype, udir, ep->busnum, ep->devnum, ep->epnum);
 545}
 546
 547static void mon_text_read_statset(struct mon_reader_text *rp,
 548        struct mon_text_ptr *p, const struct mon_event_text *ep)
 549{
 550
 551        if (ep->setup_flag == 0) {   /* Setup packet is present and captured */
 552                p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 553                    " s %02x %02x %04x %04x %04x",
 554                    ep->setup[0],
 555                    ep->setup[1],
 556                    (ep->setup[3] << 8) | ep->setup[2],
 557                    (ep->setup[5] << 8) | ep->setup[4],
 558                    (ep->setup[7] << 8) | ep->setup[6]);
 559        } else if (ep->setup_flag != '-') { /* Unable to capture setup packet */
 560                p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 561                    " %c __ __ ____ ____ ____", ep->setup_flag);
 562        } else {                     /* No setup for this kind of URB */
 563                p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 564                    " %d", ep->status);
 565        }
 566}
 567
 568static void mon_text_read_intstat(struct mon_reader_text *rp,
 569        struct mon_text_ptr *p, const struct mon_event_text *ep)
 570{
 571        p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 572            " %d:%d", ep->status, ep->interval);
 573}
 574
 575static void mon_text_read_isostat(struct mon_reader_text *rp,
 576        struct mon_text_ptr *p, const struct mon_event_text *ep)
 577{
 578        if (ep->type == 'S') {
 579                p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 580                    " %d:%d:%d", ep->status, ep->interval, ep->start_frame);
 581        } else {
 582                p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 583                    " %d:%d:%d:%d",
 584                    ep->status, ep->interval, ep->start_frame, ep->error_count);
 585        }
 586}
 587
 588static void mon_text_read_isodesc(struct mon_reader_text *rp,
 589        struct mon_text_ptr *p, const struct mon_event_text *ep)
 590{
 591        int ndesc;      /* Display this many */
 592        int i;
 593        const struct mon_iso_desc *dp;
 594
 595        p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 596            " %d", ep->numdesc);
 597        ndesc = ep->numdesc;
 598        if (ndesc > ISODESC_MAX)
 599                ndesc = ISODESC_MAX;
 600        if (ndesc < 0)
 601                ndesc = 0;
 602        dp = ep->isodesc;
 603        for (i = 0; i < ndesc; i++) {
 604                p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 605                    " %d:%u:%u", dp->status, dp->offset, dp->length);
 606                dp++;
 607        }
 608}
 609
 610static void mon_text_read_data(struct mon_reader_text *rp,
 611    struct mon_text_ptr *p, const struct mon_event_text *ep)
 612{
 613        int data_len, i;
 614
 615        if ((data_len = ep->length) > 0) {
 616                if (ep->data_flag == 0) {
 617                        p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 618                            " =");
 619                        if (data_len >= DATA_MAX)
 620                                data_len = DATA_MAX;
 621                        for (i = 0; i < data_len; i++) {
 622                                if (i % 4 == 0) {
 623                                        p->cnt += snprintf(p->pbuf + p->cnt,
 624                                            p->limit - p->cnt,
 625                                            " ");
 626                                }
 627                                p->cnt += snprintf(p->pbuf + p->cnt,
 628                                    p->limit - p->cnt,
 629                                    "%02x", ep->data[i]);
 630                        }
 631                        p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 632                            "\n");
 633                } else {
 634                        p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt,
 635                            " %c\n", ep->data_flag);
 636                }
 637        } else {
 638                p->cnt += snprintf(p->pbuf + p->cnt, p->limit - p->cnt, "\n");
 639        }
 640}
 641
 642static int mon_text_release(struct inode *inode, struct file *file)
 643{
 644        struct mon_reader_text *rp = file->private_data;
 645        struct mon_bus *mbus;
 646        /* unsigned long flags; */
 647        struct list_head *p;
 648        struct mon_event_text *ep;
 649
 650        mutex_lock(&mon_lock);
 651        mbus = inode->i_private;
 652
 653        if (mbus->nreaders <= 0) {
 654                printk(KERN_ERR TAG ": consistency error on close\n");
 655                mutex_unlock(&mon_lock);
 656                return 0;
 657        }
 658        mon_reader_del(mbus, &rp->r);
 659
 660        /*
 661         * In theory, e_list is protected by mbus->lock. However,
 662         * after mon_reader_del has finished, the following is the case:
 663         *  - we are not on reader list anymore, so new events won't be added;
 664         *  - whole mbus may be dropped if it was orphaned.
 665         * So, we better not touch mbus.
 666         */
 667        /* spin_lock_irqsave(&mbus->lock, flags); */
 668        while (!list_empty(&rp->e_list)) {
 669                p = rp->e_list.next;
 670                ep = list_entry(p, struct mon_event_text, e_link);
 671                list_del(p);
 672                --rp->nevents;
 673                kmem_cache_free(rp->e_slab, ep);
 674        }
 675        /* spin_unlock_irqrestore(&mbus->lock, flags); */
 676
 677        kmem_cache_destroy(rp->e_slab);
 678        kfree(rp->printf_buf);
 679        kfree(rp);
 680
 681        mutex_unlock(&mon_lock);
 682        return 0;
 683}
 684
 685static const struct file_operations mon_fops_text_t = {
 686        .owner =        THIS_MODULE,
 687        .open =         mon_text_open,
 688        .llseek =       no_llseek,
 689        .read =         mon_text_read_t,
 690        .release =      mon_text_release,
 691};
 692
 693static const struct file_operations mon_fops_text_u = {
 694        .owner =        THIS_MODULE,
 695        .open =         mon_text_open,
 696        .llseek =       no_llseek,
 697        .read =         mon_text_read_u,
 698        .release =      mon_text_release,
 699};
 700
 701int mon_text_add(struct mon_bus *mbus, const struct usb_bus *ubus)
 702{
 703        enum { NAMESZ = 10 };
 704        char name[NAMESZ];
 705        int busnum = ubus? ubus->busnum: 0;
 706        int rc;
 707
 708        if (mon_dir == NULL)
 709                return 0;
 710
 711        if (ubus != NULL) {
 712                rc = snprintf(name, NAMESZ, "%dt", busnum);
 713                if (rc <= 0 || rc >= NAMESZ)
 714                        goto err_print_t;
 715                mbus->dent_t = debugfs_create_file(name, 0600, mon_dir, mbus,
 716                                                             &mon_fops_text_t);
 717        }
 718
 719        rc = snprintf(name, NAMESZ, "%du", busnum);
 720        if (rc <= 0 || rc >= NAMESZ)
 721                goto err_print_u;
 722        mbus->dent_u = debugfs_create_file(name, 0600, mon_dir, mbus,
 723                                           &mon_fops_text_u);
 724
 725        rc = snprintf(name, NAMESZ, "%ds", busnum);
 726        if (rc <= 0 || rc >= NAMESZ)
 727                goto err_print_s;
 728        mbus->dent_s = debugfs_create_file(name, 0600, mon_dir, mbus,
 729                                           &mon_fops_stat);
 730
 731        return 1;
 732
 733err_print_s:
 734        debugfs_remove(mbus->dent_u);
 735        mbus->dent_u = NULL;
 736err_print_u:
 737        if (ubus != NULL) {
 738                debugfs_remove(mbus->dent_t);
 739                mbus->dent_t = NULL;
 740        }
 741err_print_t:
 742        return 0;
 743}
 744
 745void mon_text_del(struct mon_bus *mbus)
 746{
 747        debugfs_remove(mbus->dent_u);
 748        debugfs_remove(mbus->dent_t);
 749        debugfs_remove(mbus->dent_s);
 750}
 751
 752/*
 753 * Slab interface: constructor.
 754 */
 755static void mon_text_ctor(void *mem)
 756{
 757        /*
 758         * Nothing to initialize. No, really!
 759         * So, we fill it with garbage to emulate a reused object.
 760         */
 761        memset(mem, 0xe5, sizeof(struct mon_event_text));
 762}
 763
 764int __init mon_text_init(void)
 765{
 766        mon_dir = debugfs_create_dir("usbmon", usb_debug_root);
 767        return 0;
 768}
 769
 770void mon_text_exit(void)
 771{
 772        debugfs_remove(mon_dir);
 773}
 774