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