drivers/usb/usbip/stub_rx.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Copyright (C) 2003-2008 Takahiro Hirofuchi
   4  */
   5
   6 #include <asm/byteorder.h>
   7 #include <linux/kthread.h>
   8 #include <linux/usb.h>
   9 #include <linux/usb/hcd.h>
  10 #include <linux/scatterlist.h>
  11
  12 #include "usbip_common.h"
  13 #include "stub.h"
  14
  15 static int is_clear_halt_cmd(struct urb *urb)
  16 {
  17         struct usb_ctrlrequest *req;
  18
  19         req = (struct usb_ctrlrequest *) urb->setup_packet;
  20
  21          return (req->bRequest == USB_REQ_CLEAR_FEATURE) &&
  22                  (req->bRequestType == USB_RECIP_ENDPOINT) &&
  23                  (req->wValue == USB_ENDPOINT_HALT);
  24 }
  25
  26 static int is_set_interface_cmd(struct urb *urb)
  27 {
  28         struct usb_ctrlrequest *req;
  29
  30         req = (struct usb_ctrlrequest *) urb->setup_packet;
  31
  32         return (req->bRequest == USB_REQ_SET_INTERFACE) &&
  33                 (req->bRequestType == USB_RECIP_INTERFACE);
  34 }
  35
  36 static int is_set_configuration_cmd(struct urb *urb)
  37 {
  38         struct usb_ctrlrequest *req;
  39
  40         req = (struct usb_ctrlrequest *) urb->setup_packet;
  41
  42         return (req->bRequest == USB_REQ_SET_CONFIGURATION) &&
  43                 (req->bRequestType == USB_RECIP_DEVICE);
  44 }
  45
  46 static int is_reset_device_cmd(struct urb *urb)
  47 {
  48         struct usb_ctrlrequest *req;
  49         __u16 value;
  50         __u16 index;
  51
  52         req = (struct usb_ctrlrequest *) urb->setup_packet;
  53         value = le16_to_cpu(req->wValue);
  54         index = le16_to_cpu(req->wIndex);
  55
  56         if ((req->bRequest == USB_REQ_SET_FEATURE) &&
  57             (req->bRequestType == USB_RT_PORT) &&
  58             (value == USB_PORT_FEAT_RESET)) {
  59                 usbip_dbg_stub_rx("reset_device_cmd, port %u\n", index);
  60                 return 1;
  61         } else
  62                 return 0;
  63 }
  64
  65 static int tweak_clear_halt_cmd(struct urb *urb)
  66 {
  67         struct usb_ctrlrequest *req;
  68         int target_endp;
  69         int target_dir;
  70         int target_pipe;
  71         int ret;
  72
  73         req = (struct usb_ctrlrequest *) urb->setup_packet;
  74
  75         /*
  76          * The stalled endpoint is specified in the wIndex value. The endpoint
  77          * of the urb is the target of this clear_halt request (i.e., control
  78          * endpoint).
  79          */
  80         target_endp = le16_to_cpu(req->wIndex) & 0x000f;
  81
  82         /* the stalled endpoint direction is IN or OUT?. USB_DIR_IN is 0x80.  */
  83         target_dir = le16_to_cpu(req->wIndex) & 0x0080;
  84
  85         if (target_dir)
  86                 target_pipe = usb_rcvctrlpipe(urb->dev, target_endp);
  87         else
  88                 target_pipe = usb_sndctrlpipe(urb->dev, target_endp);
  89
  90         ret = usb_clear_halt(urb->dev, target_pipe);
  91         if (ret < 0)
  92                 dev_err(&urb->dev->dev,
  93                         "usb_clear_halt error: devnum %d endp %d ret %d\n",
  94                         urb->dev->devnum, target_endp, ret);
  95         else
  96                 dev_info(&urb->dev->dev,
  97                          "usb_clear_halt done: devnum %d endp %d\n",
  98                          urb->dev->devnum, target_endp);
  99
 100         return ret;
 101 }
 102
 103 static int tweak_set_interface_cmd(struct urb *urb)
 104 {
 105         struct usb_ctrlrequest *req;
 106         __u16 alternate;
 107         __u16 interface;
 108         int ret;
 109
 110         req = (struct usb_ctrlrequest *) urb->setup_packet;
 111         alternate = le16_to_cpu(req->wValue);
 112         interface = le16_to_cpu(req->wIndex);
 113
 114         usbip_dbg_stub_rx("set_interface: inf %u alt %u\n",
 115                           interface, alternate);
 116
 117         ret = usb_set_interface(urb->dev, interface, alternate);
 118         if (ret < 0)
 119                 dev_err(&urb->dev->dev,
 120                         "usb_set_interface error: inf %u alt %u ret %d\n",
 121                         interface, alternate, ret);
 122         else
 123                 dev_info(&urb->dev->dev,
 124                         "usb_set_interface done: inf %u alt %u\n",
 125                         interface, alternate);
 126
 127         return ret;
 128 }
 129
 130 static int tweak_set_configuration_cmd(struct urb *urb)
 131 {
 132         struct stub_priv *priv = (struct stub_priv *) urb->context;
 133         struct stub_device *sdev = priv->sdev;
 134         struct usb_ctrlrequest *req;
 135         __u16 config;
 136         int err;
 137
 138         req = (struct usb_ctrlrequest *) urb->setup_packet;
 139         config = le16_to_cpu(req->wValue);
 140
 141         err = usb_set_configuration(sdev->udev, config);
 142         if (err && err != -ENODEV)
 143                 dev_err(&sdev->udev->dev, "can't set config #%d, error %d\n",
 144                         config, err);
 145         return 0;
 146 }
 147
 148 static int tweak_reset_device_cmd(struct urb *urb)
 149 {
 150         struct stub_priv *priv = (struct stub_priv *) urb->context;
 151         struct stub_device *sdev = priv->sdev;
 152
 153         dev_info(&urb->dev->dev, "usb_queue_reset_device\n");
 154
 155         if (usb_lock_device_for_reset(sdev->udev, NULL) < 0) {
 156                 dev_err(&urb->dev->dev, "could not obtain lock to reset device\n");
 157                 return 0;
 158         }
 159         usb_reset_device(sdev->udev);
 160         usb_unlock_device(sdev->udev);
 161
 162         return 0;
 163 }
 164
 165 /*
 166  * clear_halt, set_interface, and set_configuration require special tricks.
 167  */
 168 static void tweak_special_requests(struct urb *urb)
 169 {
 170         if (!urb || !urb->setup_packet)
 171                 return;
 172
 173         if (usb_pipetype(urb->pipe) != PIPE_CONTROL)
 174                 return;
 175
 176         if (is_clear_halt_cmd(urb))
 177                 /* tweak clear_halt */
 178                  tweak_clear_halt_cmd(urb);
 179
 180         else if (is_set_interface_cmd(urb))
 181                 /* tweak set_interface */
 182                 tweak_set_interface_cmd(urb);
 183
 184         else if (is_set_configuration_cmd(urb))
 185                 /* tweak set_configuration */
 186                 tweak_set_configuration_cmd(urb);
 187
 188         else if (is_reset_device_cmd(urb))
 189                 tweak_reset_device_cmd(urb);
 190         else
 191                 usbip_dbg_stub_rx("no need to tweak\n");
 192 }
 193
 194 /*
 195  * stub_recv_unlink() unlinks the URB by a call to usb_unlink_urb().
 196  * By unlinking the urb asynchronously, stub_rx can continuously
 197  * process coming urbs.  Even if the urb is unlinked, its completion
 198  * handler will be called and stub_tx will send a return pdu.
 199  *
 200  * See also comments about unlinking strategy in vhci_hcd.c.
 201  */
 202 static int stub_recv_cmd_unlink(struct stub_device *sdev,
 203                                 struct usbip_header *pdu)
 204 {
 205         int ret, i;
 206         unsigned long flags;
 207         struct stub_priv *priv;
 208
 209         spin_lock_irqsave(&sdev->priv_lock, flags);
 210
 211         list_for_each_entry(priv, &sdev->priv_init, list) {
 212                 if (priv->seqnum != pdu->u.cmd_unlink.seqnum)
 213                         continue;
 214
 215                 /*
 216                  * This matched urb is not completed yet (i.e., be in
 217                  * flight in usb hcd hardware/driver). Now we are
 218                  * cancelling it. The unlinking flag means that we are
 219                  * now not going to return the normal result pdu of a
 220                  * submission request, but going to return a result pdu
 221                  * of the unlink request.
 222                  */
 223                 priv->unlinking = 1;
 224
 225                 /*
 226                  * In the case that unlinking flag is on, prev->seqnum
 227                  * is changed from the seqnum of the cancelling urb to
 228                  * the seqnum of the unlink request. This will be used
 229                  * to make the result pdu of the unlink request.
 230                  */
 231                 priv->seqnum = pdu->base.seqnum;
 232
 233                 spin_unlock_irqrestore(&sdev->priv_lock, flags);
 234
 235                 /*
 236                  * usb_unlink_urb() is now out of spinlocking to avoid
 237                  * spinlock recursion since stub_complete() is
 238                  * sometimes called in this context but not in the
 239                  * interrupt context.  If stub_complete() is executed
 240                  * before we call usb_unlink_urb(), usb_unlink_urb()
 241                  * will return an error value. In this case, stub_tx
 242                  * will return the result pdu of this unlink request
 243                  * though submission is completed and actual unlinking
 244                  * is not executed. OK?
 245                  */
 246                 /* In the above case, urb->status is not -ECONNRESET,
 247                  * so a driver in a client host will know the failure
 248                  * of the unlink request ?
 249                  */
 250                 for (i = priv->completed_urbs; i < priv->num_urbs; i++) {
 251                         ret = usb_unlink_urb(priv->urbs[i]);
 252                         if (ret != -EINPROGRESS)
 253                                 dev_err(&priv->urbs[i]->dev->dev,
 254                                         "failed to unlink %d/%d urb of seqnum %lu, ret %d\n",
 255                                         i + 1, priv->num_urbs,
 256                                         priv->seqnum, ret);
 257                 }
 258                 return 0;
 259         }
 260
 261         usbip_dbg_stub_rx("seqnum %d is not pending\n",
 262                           pdu->u.cmd_unlink.seqnum);
 263
 264         /*
 265          * The urb of the unlink target is not found in priv_init queue. It was
 266          * already completed and its results is/was going to be sent by a
 267          * CMD_RET pdu. In this case, usb_unlink_urb() is not needed. We only
 268          * return the completeness of this unlink request to vhci_hcd.
 269          */
 270         stub_enqueue_ret_unlink(sdev, pdu->base.seqnum, 0);
 271
 272         spin_unlock_irqrestore(&sdev->priv_lock, flags);
 273
 274         return 0;
 275 }
 276
 277 static int valid_request(struct stub_device *sdev, struct usbip_header *pdu)
 278 {
 279         struct usbip_device *ud = &sdev->ud;
 280         int valid = 0;
 281
 282         if (pdu->base.devid == sdev->devid) {
 283                 spin_lock_irq(&ud->lock);
 284                 if (ud->status == SDEV_ST_USED) {
 285                         /* A request is valid. */
 286                         valid = 1;
 287                 }
 288                 spin_unlock_irq(&ud->lock);
 289         }
 290
 291         return valid;
 292 }
 293
 294 static struct stub_priv *stub_priv_alloc(struct stub_device *sdev,
 295                                          struct usbip_header *pdu)
 296 {
 297         struct stub_priv *priv;
 298         struct usbip_device *ud = &sdev->ud;
 299         unsigned long flags;
 300
 301         spin_lock_irqsave(&sdev->priv_lock, flags);
 302
 303         priv = kmem_cache_zalloc(stub_priv_cache, GFP_ATOMIC);
 304         if (!priv) {
 305                 dev_err(&sdev->udev->dev, "alloc stub_priv\n");
 306                 spin_unlock_irqrestore(&sdev->priv_lock, flags);
 307                 usbip_event_add(ud, SDEV_EVENT_ERROR_MALLOC);
 308                 return NULL;
 309         }
 310
 311         priv->seqnum = pdu->base.seqnum;
 312         priv->sdev = sdev;
 313
 314         /*
 315          * After a stub_priv is linked to a list_head,
 316          * our error handler can free allocated data.
 317          */
 318         list_add_tail(&priv->list, &sdev->priv_init);
 319
 320         spin_unlock_irqrestore(&sdev->priv_lock, flags);
 321
 322         return priv;
 323 }
 324
 325 static int get_pipe(struct stub_device *sdev, struct usbip_header *pdu)
 326 {
 327         struct usb_device *udev = sdev->udev;
 328         struct usb_host_endpoint *ep;
 329         struct usb_endpoint_descriptor *epd = NULL;
 330         int epnum = pdu->base.ep;
 331         int dir = pdu->base.direction;
 332
 333         if (epnum < 0 || epnum > 15)
 334                 goto err_ret;
 335
 336         if (dir == USBIP_DIR_IN)
 337                 ep = udev->ep_in[epnum & 0x7f];
 338         else
 339                 ep = udev->ep_out[epnum & 0x7f];
 340         if (!ep)
 341                 goto err_ret;
 342
 343         epd = &ep->desc;
 344
 345         if (usb_endpoint_xfer_control(epd)) {
 346                 if (dir == USBIP_DIR_OUT)
 347                         return usb_sndctrlpipe(udev, epnum);
 348                 else
 349                         return usb_rcvctrlpipe(udev, epnum);
 350         }
 351
 352         if (usb_endpoint_xfer_bulk(epd)) {
 353                 if (dir == USBIP_DIR_OUT)
 354                         return usb_sndbulkpipe(udev, epnum);
 355                 else
 356                         return usb_rcvbulkpipe(udev, epnum);
 357         }
 358
 359         if (usb_endpoint_xfer_int(epd)) {
 360                 if (dir == USBIP_DIR_OUT)
 361                         return usb_sndintpipe(udev, epnum);
 362                 else
 363                         return usb_rcvintpipe(udev, epnum);
 364         }
 365
 366         if (usb_endpoint_xfer_isoc(epd)) {
 367                 /* validate number of packets */
 368                 if (pdu->u.cmd_submit.number_of_packets < 0 ||
 369                     pdu->u.cmd_submit.number_of_packets >
 370                     USBIP_MAX_ISO_PACKETS) {
 371                         dev_err(&sdev->udev->dev,
 372                                 "CMD_SUBMIT: isoc invalid num packets %d\n",
 373                                 pdu->u.cmd_submit.number_of_packets);
 374                         return -1;
 375                 }
 376                 if (dir == USBIP_DIR_OUT)
 377                         return usb_sndisocpipe(udev, epnum);
 378                 else
 379                         return usb_rcvisocpipe(udev, epnum);
 380         }
 381
 382 err_ret:
 383         /* NOT REACHED */
 384         dev_err(&sdev->udev->dev, "CMD_SUBMIT: invalid epnum %d\n", epnum);
 385         return -1;
 386 }
 387
 388 static void masking_bogus_flags(struct urb *urb)
 389 {
 390         int                             xfertype;
 391         struct usb_device               *dev;
 392         struct usb_host_endpoint        *ep;
 393         int                             is_out;
 394         unsigned int    allowed;
 395
 396         if (!urb || urb->hcpriv || !urb->complete)
 397                 return;
 398         dev = urb->dev;
 399         if ((!dev) || (dev->state < USB_STATE_UNAUTHENTICATED))
 400                 return;
 401
 402         ep = (usb_pipein(urb->pipe) ? dev->ep_in : dev->ep_out)
 403                 [usb_pipeendpoint(urb->pipe)];
 404         if (!ep)
 405                 return;
 406
 407         xfertype = usb_endpoint_type(&ep->desc);
 408         if (xfertype == USB_ENDPOINT_XFER_CONTROL) {
 409                 struct usb_ctrlrequest *setup =
 410                         (struct usb_ctrlrequest *) urb->setup_packet;
 411
 412                 if (!setup)
 413                         return;
 414                 is_out = !(setup->bRequestType & USB_DIR_IN) ||
 415                         !setup->wLength;
 416         } else {
 417                 is_out = usb_endpoint_dir_out(&ep->desc);
 418         }
 419
 420         /* enforce simple/standard policy */
 421         allowed = (URB_NO_TRANSFER_DMA_MAP | URB_NO_INTERRUPT |
 422                    URB_DIR_MASK | URB_FREE_BUFFER);
 423         switch (xfertype) {
 424         case USB_ENDPOINT_XFER_BULK:
 425                 if (is_out)
 426                         allowed |= URB_ZERO_PACKET;
 427                 /* FALLTHROUGH */
 428         case USB_ENDPOINT_XFER_CONTROL:
 429                 allowed |= URB_NO_FSBR; /* only affects UHCI */
 430                 /* FALLTHROUGH */
 431         default:                        /* all non-iso endpoints */
 432                 if (!is_out)
 433                         allowed |= URB_SHORT_NOT_OK;
 434                 break;
 435         case USB_ENDPOINT_XFER_ISOC:
 436                 allowed |= URB_ISO_ASAP;
 437                 break;
 438         }
 439         urb->transfer_flags &= allowed;
 440 }
 441
 442 static int stub_recv_xbuff(struct usbip_device *ud, struct stub_priv *priv)
 443 {
 444         int ret;
 445         int i;
 446
 447         for (i = 0; i < priv->num_urbs; i++) {
 448                 ret = usbip_recv_xbuff(ud, priv->urbs[i]);
 449                 if (ret < 0)
 450                         break;
 451         }
 452
 453         return ret;
 454 }
 455
 456 static void stub_recv_cmd_submit(struct stub_device *sdev,
 457                                  struct usbip_header *pdu)
 458 {
 459         struct stub_priv *priv;
 460         struct usbip_device *ud = &sdev->ud;
 461         struct usb_device *udev = sdev->udev;
 462         struct scatterlist *sgl = NULL, *sg;
 463         void *buffer = NULL;
 464         unsigned long long buf_len;
 465         int nents;
 466         int num_urbs = 1;
 467         int pipe = get_pipe(sdev, pdu);
 468         int use_sg = pdu->u.cmd_submit.transfer_flags & URB_DMA_MAP_SG;
 469         int support_sg = 1;
 470         int np = 0;
 471         int ret, i;
 472
 473         if (pipe == -1)
 474                 return;
 475
 476         /*
 477          * Smatch reported the error case where use_sg is true and buf_len is 0.
 478          * In this case, It adds SDEV_EVENT_ERROR_MALLOC and stub_priv will be
 479          * released by stub event handler and connection will be shut down.
 480          */
 481         priv = stub_priv_alloc(sdev, pdu);
 482         if (!priv)
 483                 return;
 484
 485         buf_len = (unsigned long long)pdu->u.cmd_submit.transfer_buffer_length;
 486
 487         if (use_sg && !buf_len) {
 488                 dev_err(&udev->dev, "sg buffer with zero length\n");
 489                 goto err_malloc;
 490         }
 491
 492         /* allocate urb transfer buffer, if needed */
 493         if (buf_len) {
 494                 if (use_sg) {
 495                         sgl = sgl_alloc(buf_len, GFP_KERNEL, &nents);
 496                         if (!sgl)
 497                                 goto err_malloc;
 498
 499                         /* Check if the server's HCD supports SG */
 500                         if (!udev->bus->sg_tablesize) {
 501                                 /*
 502                                  * If the server's HCD doesn't support SG, break
 503                                  * a single SG request into several URBs and map
 504                                  * each SG list entry to corresponding URB
 505                                  * buffer. The previously allocated SG list is
 506                                  * stored in priv->sgl (If the server's HCD
 507                                  * support SG, SG list is stored only in
 508                                  * urb->sg) and it is used as an indicator that
 509                                  * the server split single SG request into
 510                                  * several URBs. Later, priv->sgl is used by
 511                                  * stub_complete() and stub_send_ret_submit() to
 512                                  * reassemble the divied URBs.
 513                                  */
 514                                 support_sg = 0;
 515                                 num_urbs = nents;
 516                                 priv->completed_urbs = 0;
 517                                 pdu->u.cmd_submit.transfer_flags &=
 518                                                                 ~URB_DMA_MAP_SG;
 519                         }
 520                 } else {
 521                         buffer = kzalloc(buf_len, GFP_KERNEL);
 522                         if (!buffer)
 523                                 goto err_malloc;
 524                 }
 525         }
 526
 527         /* allocate urb array */
 528         priv->num_urbs = num_urbs;
 529         priv->urbs = kmalloc_array(num_urbs, sizeof(*priv->urbs), GFP_KERNEL);
 530         if (!priv->urbs)
 531                 goto err_urbs;
 532
 533         /* setup a urb */
 534         if (support_sg) {
 535                 if (usb_pipeisoc(pipe))
 536                         np = pdu->u.cmd_submit.number_of_packets;
 537
 538                 priv->urbs[0] = usb_alloc_urb(np, GFP_KERNEL);
 539                 if (!priv->urbs[0])
 540                         goto err_urb;
 541
 542                 if (buf_len) {
 543                         if (use_sg) {
 544                                 priv->urbs[0]->sg = sgl;
 545                                 priv->urbs[0]->num_sgs = nents;
 546                                 priv->urbs[0]->transfer_buffer = NULL;
 547                         } else {
 548                                 priv->urbs[0]->transfer_buffer = buffer;
 549                         }
 550                 }
 551
 552                 /* copy urb setup packet */
 553                 priv->urbs[0]->setup_packet = kmemdup(&pdu->u.cmd_submit.setup,
 554                                         8, GFP_KERNEL);
 555                 if (!priv->urbs[0]->setup_packet) {
 556                         usbip_event_add(ud, SDEV_EVENT_ERROR_MALLOC);
 557                         return;
 558                 }
 559
 560                 usbip_pack_pdu(pdu, priv->urbs[0], USBIP_CMD_SUBMIT, 0);
 561         } else {
 562                 for_each_sg(sgl, sg, nents, i) {
 563                         priv->urbs[i] = usb_alloc_urb(0, GFP_KERNEL);
 564                         /* The URBs which is previously allocated will be freed
 565                          * in stub_device_cleanup_urbs() if error occurs.
 566                          */
 567                         if (!priv->urbs[i])
 568                                 goto err_urb;
 569
 570                         usbip_pack_pdu(pdu, priv->urbs[i], USBIP_CMD_SUBMIT, 0);
 571                         priv->urbs[i]->transfer_buffer = sg_virt(sg);
 572                         priv->urbs[i]->transfer_buffer_length = sg->length;
 573                 }
 574                 priv->sgl = sgl;
 575         }
 576
 577         for (i = 0; i < num_urbs; i++) {
 578                 /* set other members from the base header of pdu */
 579                 priv->urbs[i]->context = (void *) priv;
 580                 priv->urbs[i]->dev = udev;
 581                 priv->urbs[i]->pipe = pipe;
 582                 priv->urbs[i]->complete = stub_complete;
 583
 584                 /* no need to submit an intercepted request, but harmless? */
 585                 tweak_special_requests(priv->urbs[i]);
 586
 587                 masking_bogus_flags(priv->urbs[i]);
 588         }
 589
 590         if (stub_recv_xbuff(ud, priv) < 0)
 591                 return;
 592
 593         if (usbip_recv_iso(ud, priv->urbs[0]) < 0)
 594                 return;
 595
 596         /* urb is now ready to submit */
 597         for (i = 0; i < priv->num_urbs; i++) {
 598                 ret = usb_submit_urb(priv->urbs[i], GFP_KERNEL);
 599
 600                 if (ret == 0)
 601                         usbip_dbg_stub_rx("submit urb ok, seqnum %u\n",
 602                                         pdu->base.seqnum);
 603                 else {
 604                         dev_err(&udev->dev, "submit_urb error, %d\n", ret);
 605                         usbip_dump_header(pdu);
 606                         usbip_dump_urb(priv->urbs[i]);
 607
 608                         /*
 609                          * Pessimistic.
 610                          * This connection will be discarded.
 611                          */
 612                         usbip_event_add(ud, SDEV_EVENT_ERROR_SUBMIT);
 613                         break;
 614                 }
 615         }
 616
 617         usbip_dbg_stub_rx("Leave\n");
 618         return;
 619
 620 err_urb:
 621         kfree(priv->urbs);
 622 err_urbs:
 623         kfree(buffer);
 624         sgl_free(sgl);
 625 err_malloc:
 626         usbip_event_add(ud, SDEV_EVENT_ERROR_MALLOC);
 627 }
 628
 629 /* recv a pdu */
 630 static void stub_rx_pdu(struct usbip_device *ud)
 631 {
 632         int ret;
 633         struct usbip_header pdu;
 634         struct stub_device *sdev = container_of(ud, struct stub_device, ud);
 635         struct device *dev = &sdev->udev->dev;
 636
 637         usbip_dbg_stub_rx("Enter\n");
 638
 639         memset(&pdu, 0, sizeof(pdu));
 640
 641         /* receive a pdu header */
 642         ret = usbip_recv(ud->tcp_socket, &pdu, sizeof(pdu));
 643         if (ret != sizeof(pdu)) {
 644                 dev_err(dev, "recv a header, %d\n", ret);
 645                 usbip_event_add(ud, SDEV_EVENT_ERROR_TCP);
 646                 return;
 647         }
 648
 649         usbip_header_correct_endian(&pdu, 0);
 650
 651         if (usbip_dbg_flag_stub_rx)
 652                 usbip_dump_header(&pdu);
 653
 654         if (!valid_request(sdev, &pdu)) {
 655                 dev_err(dev, "recv invalid request\n");
 656                 usbip_event_add(ud, SDEV_EVENT_ERROR_TCP);
 657                 return;
 658         }
 659
 660         switch (pdu.base.command) {
 661         case USBIP_CMD_UNLINK:
 662                 stub_recv_cmd_unlink(sdev, &pdu);
 663                 break;
 664
 665         case USBIP_CMD_SUBMIT:
 666                 stub_recv_cmd_submit(sdev, &pdu);
 667                 break;
 668
 669         default:
 670                 /* NOTREACHED */
 671                 dev_err(dev, "unknown pdu\n");
 672                 usbip_event_add(ud, SDEV_EVENT_ERROR_TCP);
 673                 break;
 674         }
 675 }
 676
 677 int stub_rx_loop(void *data)
 678 {
 679         struct usbip_device *ud = data;
 680
 681         while (!kthread_should_stop()) {
 682                 if (usbip_event_happened(ud))
 683                         break;
 684
 685                 stub_rx_pdu(ud);
 686         }
 687
 688         return 0;
 689 }