1// SPDX-License-Identifier: GPL-2.0 2/* 3 * Released under the GPLv2 only. 4 */ 5 6#include <linux/module.h> 7#include <linux/string.h> 8#include <linux/bitops.h> 9#include <linux/slab.h> 10#include <linux/log2.h> 11#include <linux/kmsan.h> 12#include <linux/usb.h> 13#include <linux/wait.h> 14#include <linux/usb/hcd.h> 15#include <linux/scatterlist.h> 16 17#define to_urb(d) container_of(d, struct urb, kref) 18 19 20static void urb_destroy(struct kref *kref) 21{ 22 struct urb *urb = to_urb(kref); 23 24 if (urb->transfer_flags & URB_FREE_BUFFER) 25 kfree(urb->transfer_buffer); 26 27 kfree(urb); 28} 29 30/** 31 * usb_init_urb - initializes a urb so that it can be used by a USB driver 32 * @urb: pointer to the urb to initialize 33 * 34 * Initializes a urb so that the USB subsystem can use it properly. 35 * 36 * If a urb is created with a call to usb_alloc_urb() it is not 37 * necessary to call this function. Only use this if you allocate the 38 * space for a struct urb on your own. If you call this function, be 39 * careful when freeing the memory for your urb that it is no longer in 40 * use by the USB core. 41 * 42 * Only use this function if you _really_ understand what you are doing. 43 */ 44void usb_init_urb(struct urb *urb) 45{ 46 if (urb) { 47 memset(urb, 0, sizeof(*urb)); 48 kref_init(&urb->kref); 49 INIT_LIST_HEAD(&urb->urb_list); 50 INIT_LIST_HEAD(&urb->anchor_list); 51 } 52} 53EXPORT_SYMBOL_GPL(usb_init_urb); 54 55/** 56 * usb_alloc_urb - creates a new urb for a USB driver to use 57 * @iso_packets: number of iso packets for this urb 58 * @mem_flags: the type of memory to allocate, see kmalloc() for a list of 59 * valid options for this. 60 * 61 * Creates an urb for the USB driver to use, initializes a few internal 62 * structures, increments the usage counter, and returns a pointer to it. 63 * 64 * If the driver want to use this urb for interrupt, control, or bulk 65 * endpoints, pass '0' as the number of iso packets. 66 * 67 * The driver must call usb_free_urb() when it is finished with the urb. 68 * 69 * Return: A pointer to the new urb, or %NULL if no memory is available. 70 */ 71struct urb *usb_alloc_urb(int iso_packets, gfp_t mem_flags) 72{ 73 struct urb *urb; 74 75 urb = kmalloc(struct_size(urb, iso_frame_desc, iso_packets), 76 mem_flags); 77 if (!urb) 78 return NULL; 79 usb_init_urb(urb); 80 return urb; 81} 82EXPORT_SYMBOL_GPL(usb_alloc_urb); 83 84/** 85 * usb_free_urb - frees the memory used by a urb when all users of it are finished 86 * @urb: pointer to the urb to free, may be NULL 87 * 88 * Must be called when a user of a urb is finished with it. When the last user 89 * of the urb calls this function, the memory of the urb is freed. 90 * 91 * Note: The transfer buffer associated with the urb is not freed unless the 92 * URB_FREE_BUFFER transfer flag is set. 93 */ 94void usb_free_urb(struct urb *urb) 95{ 96 if (urb) 97 kref_put(&urb->kref, urb_destroy); 98} 99EXPORT_SYMBOL_GPL(usb_free_urb); 100 101/** 102 * usb_get_urb - increments the reference count of the urb 103 * @urb: pointer to the urb to modify, may be NULL 104 * 105 * This must be called whenever a urb is transferred from a device driver to a 106 * host controller driver. This allows proper reference counting to happen 107 * for urbs. 108 * 109 * Return: A pointer to the urb with the incremented reference counter. 110 */ 111struct urb *usb_get_urb(struct urb *urb) 112{ 113 if (urb) 114 kref_get(&urb->kref); 115 return urb; 116} 117EXPORT_SYMBOL_GPL(usb_get_urb); 118 119/** 120 * usb_anchor_urb - anchors an URB while it is processed 121 * @urb: pointer to the urb to anchor 122 * @anchor: pointer to the anchor 123 * 124 * This can be called to have access to URBs which are to be executed 125 * without bothering to track them 126 */ 127void usb_anchor_urb(struct urb *urb, struct usb_anchor *anchor) 128{ 129 unsigned long flags; 130 131 spin_lock_irqsave(&anchor->lock, flags); 132 usb_get_urb(urb); 133 list_add_tail(&urb->anchor_list, &anchor->urb_list); 134 urb->anchor = anchor; 135 136 if (unlikely(anchor->poisoned)) 137 atomic_inc(&urb->reject); 138 139 spin_unlock_irqrestore(&anchor->lock, flags); 140} 141EXPORT_SYMBOL_GPL(usb_anchor_urb); 142 143static int usb_anchor_check_wakeup(struct usb_anchor *anchor) 144{ 145 return atomic_read(&anchor->suspend_wakeups) == 0 && 146 list_empty(&anchor->urb_list); 147} 148 149/* Callers must hold anchor->lock */ 150static void __usb_unanchor_urb(struct urb *urb, struct usb_anchor *anchor) 151{ 152 urb->anchor = NULL; 153 list_del(&urb->anchor_list); 154 usb_put_urb(urb); 155 if (usb_anchor_check_wakeup(anchor)) 156 wake_up(&anchor->wait); 157} 158 159/** 160 * usb_unanchor_urb - unanchors an URB 161 * @urb: pointer to the urb to anchor 162 * 163 * Call this to stop the system keeping track of this URB 164 */ 165void usb_unanchor_urb(struct urb *urb) 166{ 167 unsigned long flags; 168 struct usb_anchor *anchor; 169 170 if (!urb) 171 return; 172 173 anchor = urb->anchor; 174 if (!anchor) 175 return; 176 177 spin_lock_irqsave(&anchor->lock, flags); 178 /* 179 * At this point, we could be competing with another thread which 180 * has the same intention. To protect the urb from being unanchored 181 * twice, only the winner of the race gets the job. 182 */ 183 if (likely(anchor == urb->anchor)) 184 __usb_unanchor_urb(urb, anchor); 185 spin_unlock_irqrestore(&anchor->lock, flags); 186} 187EXPORT_SYMBOL_GPL(usb_unanchor_urb); 188 189/*-------------------------------------------------------------------*/ 190 191static const int pipetypes[4] = { 192 PIPE_CONTROL, PIPE_ISOCHRONOUS, PIPE_BULK, PIPE_INTERRUPT 193}; 194 195/** 196 * usb_pipe_type_check - sanity check of a specific pipe for a usb device 197 * @dev: struct usb_device to be checked 198 * @pipe: pipe to check 199 * 200 * This performs a light-weight sanity check for the endpoint in the 201 * given usb device. It returns 0 if the pipe is valid for the specific usb 202 * device, otherwise a negative error code. 203 */ 204int usb_pipe_type_check(struct usb_device *dev, unsigned int pipe) 205{ 206 const struct usb_host_endpoint *ep; 207 208 ep = usb_pipe_endpoint(dev, pipe); 209 if (!ep) 210 return -EINVAL; 211 if (usb_pipetype(pipe) != pipetypes[usb_endpoint_type(&ep->desc)]) 212 return -EINVAL; 213 return 0; 214} 215EXPORT_SYMBOL_GPL(usb_pipe_type_check); 216 217/** 218 * usb_urb_ep_type_check - sanity check of endpoint in the given urb 219 * @urb: urb to be checked 220 * 221 * This performs a light-weight sanity check for the endpoint in the 222 * given urb. It returns 0 if the urb contains a valid endpoint, otherwise 223 * a negative error code. 224 */ 225int usb_urb_ep_type_check(const struct urb *urb) 226{ 227 return usb_pipe_type_check(urb->dev, urb->pipe); 228} 229EXPORT_SYMBOL_GPL(usb_urb_ep_type_check); 230 231/** 232 * usb_submit_urb - issue an asynchronous transfer request for an endpoint 233 * @urb: pointer to the urb describing the request 234 * @mem_flags: the type of memory to allocate, see kmalloc() for a list 235 * of valid options for this. 236 * 237 * This submits a transfer request, and transfers control of the URB 238 * describing that request to the USB subsystem. Request completion will 239 * be indicated later, asynchronously, by calling the completion handler. 240 * The three types of completion are success, error, and unlink 241 * (a software-induced fault, also called "request cancellation"). 242 * 243 * URBs may be submitted in interrupt context. 244 * 245 * The caller must have correctly initialized the URB before submitting 246 * it. Functions such as usb_fill_bulk_urb() and usb_fill_control_urb() are 247 * available to ensure that most fields are correctly initialized, for 248 * the particular kind of transfer, although they will not initialize 249 * any transfer flags. 250 * 251 * If the submission is successful, the complete() callback from the URB 252 * will be called exactly once, when the USB core and Host Controller Driver 253 * (HCD) are finished with the URB. When the completion function is called, 254 * control of the URB is returned to the device driver which issued the 255 * request. The completion handler may then immediately free or reuse that 256 * URB. 257 * 258 * With few exceptions, USB device drivers should never access URB fields 259 * provided by usbcore or the HCD until its complete() is called. 260 * The exceptions relate to periodic transfer scheduling. For both 261 * interrupt and isochronous urbs, as part of successful URB submission 262 * urb->interval is modified to reflect the actual transfer period used 263 * (normally some power of two units). And for isochronous urbs, 264 * urb->start_frame is modified to reflect when the URB's transfers were 265 * scheduled to start. 266 * 267 * Not all isochronous transfer scheduling policies will work, but most 268 * host controller drivers should easily handle ISO queues going from now 269 * until 10-200 msec into the future. Drivers should try to keep at 270 * least one or two msec of data in the queue; many controllers require 271 * that new transfers start at least 1 msec in the future when they are 272 * added. If the driver is unable to keep up and the queue empties out, 273 * the behavior for new submissions is governed by the URB_ISO_ASAP flag. 274 * If the flag is set, or if the queue is idle, then the URB is always 275 * assigned to the first available (and not yet expired) slot in the 276 * endpoint's schedule. If the flag is not set and the queue is active 277 * then the URB is always assigned to the next slot in the schedule 278 * following the end of the endpoint's previous URB, even if that slot is 279 * in the past. When a packet is assigned in this way to a slot that has 280 * already expired, the packet is not transmitted and the corresponding 281 * usb_iso_packet_descriptor's status field will return -EXDEV. If this 282 * would happen to all the packets in the URB, submission fails with a 283 * -EXDEV error code. 284 * 285 * For control endpoints, the synchronous usb_control_msg() call is 286 * often used (in non-interrupt context) instead of this call. 287 * That is often used through convenience wrappers, for the requests 288 * that are standardized in the USB 2.0 specification. For bulk 289 * endpoints, a synchronous usb_bulk_msg() call is available. 290 * 291 * Return: 292 * 0 on successful submissions. A negative error number otherwise. 293 * 294 * Request Queuing: 295 * 296 * URBs may be submitted to endpoints before previous ones complete, to 297 * minimize the impact of interrupt latencies and system overhead on data 298 * throughput. With that queuing policy, an endpoint's queue would never 299 * be empty. This is required for continuous isochronous data streams, 300 * and may also be required for some kinds of interrupt transfers. Such 301 * queuing also maximizes bandwidth utilization by letting USB controllers 302 * start work on later requests before driver software has finished the 303 * completion processing for earlier (successful) requests. 304 * 305 * As of Linux 2.6, all USB endpoint transfer queues support depths greater 306 * than one. This was previously a HCD-specific behavior, except for ISO 307 * transfers. Non-isochronous endpoint queues are inactive during cleanup 308 * after faults (transfer errors or cancellation). 309 * 310 * Reserved Bandwidth Transfers: 311 * 312 * Periodic transfers (interrupt or isochronous) are performed repeatedly, 313 * using the interval specified in the urb. Submitting the first urb to 314 * the endpoint reserves the bandwidth necessary to make those transfers. 315 * If the USB subsystem can't allocate sufficient bandwidth to perform 316 * the periodic request, submitting such a periodic request should fail. 317 * 318 * For devices under xHCI, the bandwidth is reserved at configuration time, or 319 * when the alt setting is selected. If there is not enough bus bandwidth, the 320 * configuration/alt setting request will fail. Therefore, submissions to 321 * periodic endpoints on devices under xHCI should never fail due to bandwidth 322 * constraints. 323 * 324 * Device drivers must explicitly request that repetition, by ensuring that 325 * some URB is always on the endpoint's queue (except possibly for short 326 * periods during completion callbacks). When there is no longer an urb 327 * queued, the endpoint's bandwidth reservation is canceled. This means 328 * drivers can use their completion handlers to ensure they keep bandwidth 329 * they need, by reinitializing and resubmitting the just-completed urb 330 * until the driver longer needs that periodic bandwidth. 331 * 332 * Memory Flags: 333 * 334 * The general rules for how to decide which mem_flags to use 335 * are the same as for kmalloc. There are four 336 * different possible values; GFP_KERNEL, GFP_NOFS, GFP_NOIO and 337 * GFP_ATOMIC. 338 * 339 * GFP_NOFS is not ever used, as it has not been implemented yet. 340 * 341 * GFP_ATOMIC is used when 342 * (a) you are inside a completion handler, an interrupt, bottom half, 343 * tasklet or timer, or 344 * (b) you are holding a spinlock or rwlock (does not apply to 345 * semaphores), or 346 * (c) current->state != TASK_RUNNING, this is the case only after 347 * you've changed it. 348 * 349 * GFP_NOIO is used in the block io path and error handling of storage 350 * devices. 351 * 352 * All other situations use GFP_KERNEL. 353 * 354 * Some more specific rules for mem_flags can be inferred, such as 355 * (1) start_xmit, timeout, and receive methods of network drivers must 356 * use GFP_ATOMIC (they are called with a spinlock held); 357 * (2) queuecommand methods of scsi drivers must use GFP_ATOMIC (also 358 * called with a spinlock held); 359 * (3) If you use a kernel thread with a network driver you must use 360 * GFP_NOIO, unless (b) or (c) apply; 361 * (4) after you have done a down() you can use GFP_KERNEL, unless (b) or (c) 362 * apply or your are in a storage driver's block io path; 363 * (5) USB probe and disconnect can use GFP_KERNEL unless (b) or (c) apply; and 364 * (6) changing firmware on a running storage or net device uses 365 * GFP_NOIO, unless b) or c) apply 366 * 367 */ 368int usb_submit_urb(struct urb *urb, gfp_t mem_flags) 369{ 370 int xfertype, max; 371 struct usb_device *dev; 372 struct usb_host_endpoint *ep; 373 int is_out; 374 unsigned int allowed; 375 376 if (!urb || !urb->complete) 377 return -EINVAL; 378 if (urb->hcpriv) { 379 WARN_ONCE(1, "URB %pK submitted while active\n", urb); 380 return -EBUSY; 381 } 382 383 dev = urb->dev; 384 if ((!dev) || (dev->state < USB_STATE_UNAUTHENTICATED)) 385 return -ENODEV; 386 387 /* For now, get the endpoint from the pipe. Eventually drivers 388 * will be required to set urb->ep directly and we will eliminate 389 * urb->pipe. 390 */ 391 ep = usb_pipe_endpoint(dev, urb->pipe); 392 if (!ep) 393 return -ENOENT; 394 395 urb->ep = ep; 396 urb->status = -EINPROGRESS; 397 urb->actual_length = 0; 398 399 /* Lots of sanity checks, so HCDs can rely on clean data 400 * and don't need to duplicate tests 401 */ 402 xfertype = usb_endpoint_type(&ep->desc); 403 if (xfertype == USB_ENDPOINT_XFER_CONTROL) { 404 struct usb_ctrlrequest *setup = 405 (struct usb_ctrlrequest *) urb->setup_packet; 406 407 if (!setup) 408 return -ENOEXEC; 409 is_out = !(setup->bRequestType & USB_DIR_IN) || 410 !setup->wLength; 411 dev_WARN_ONCE(&dev->dev, (usb_pipeout(urb->pipe) != is_out), 412 "BOGUS control dir, pipe %x doesn't match bRequestType %x\n", 413 urb->pipe, setup->bRequestType); 414 if (le16_to_cpu(setup->wLength) != urb->transfer_buffer_length) { 415 dev_dbg(&dev->dev, "BOGUS control len %d doesn't match transfer length %d\n", 416 le16_to_cpu(setup->wLength), 417 urb->transfer_buffer_length); 418 return -EBADR; 419 } 420 } else { 421 is_out = usb_endpoint_dir_out(&ep->desc); 422 } 423 424 /* Clear the internal flags and cache the direction for later use */ 425 urb->transfer_flags &= ~(URB_DIR_MASK | URB_DMA_MAP_SINGLE | 426 URB_DMA_MAP_PAGE | URB_DMA_MAP_SG | URB_MAP_LOCAL | 427 URB_SETUP_MAP_SINGLE | URB_SETUP_MAP_LOCAL | 428 URB_DMA_SG_COMBINED); 429 urb->transfer_flags |= (is_out ? URB_DIR_OUT : URB_DIR_IN); 430 kmsan_handle_urb(urb, is_out); 431 432 if (xfertype != USB_ENDPOINT_XFER_CONTROL && 433 dev->state < USB_STATE_CONFIGURED) 434 return -ENODEV; 435 436 max = usb_endpoint_maxp(&ep->desc); 437 if (max <= 0) { 438 dev_dbg(&dev->dev, 439 "bogus endpoint ep%d%s in %s (bad maxpacket %d)\n", 440 usb_endpoint_num(&ep->desc), is_out ? "out" : "in", 441 __func__, max); 442 return -EMSGSIZE; 443 } 444 445 /* periodic transfers limit size per frame/uframe, 446 * but drivers only control those sizes for ISO. 447 * while we're checking, initialize return status. 448 */ 449 if (xfertype == USB_ENDPOINT_XFER_ISOC) { 450 int n, len; 451 452 /* SuperSpeed isoc endpoints have up to 16 bursts of up to 453 * 3 packets each 454 */ 455 if (dev->speed >= USB_SPEED_SUPER) { 456 int burst = 1 + ep->ss_ep_comp.bMaxBurst; 457 int mult = USB_SS_MULT(ep->ss_ep_comp.bmAttributes); 458 max *= burst; 459 max *= mult; 460 } 461 462 if (dev->speed == USB_SPEED_SUPER_PLUS && 463 USB_SS_SSP_ISOC_COMP(ep->ss_ep_comp.bmAttributes)) { 464 struct usb_ssp_isoc_ep_comp_descriptor *isoc_ep_comp; 465 466 isoc_ep_comp = &ep->ssp_isoc_ep_comp; 467 max = le32_to_cpu(isoc_ep_comp->dwBytesPerInterval); 468 } 469 470 /* "high bandwidth" mode, 1-3 packets/uframe? */ 471 if (dev->speed == USB_SPEED_HIGH) 472 max *= usb_endpoint_maxp_mult(&ep->desc); 473 474 if (urb->number_of_packets <= 0) 475 return -EINVAL; 476 for (n = 0; n < urb->number_of_packets; n++) { 477 len = urb->iso_frame_desc[n].length; 478 if (len < 0 || len > max) 479 return -EMSGSIZE; 480 urb->iso_frame_desc[n].status = -EXDEV; 481 urb->iso_frame_desc[n].actual_length = 0; 482 } 483 } else if (urb->num_sgs && !urb->dev->bus->no_sg_constraint) { 484 struct scatterlist *sg; 485 int i; 486 487 for_each_sg(urb->sg, sg, urb->num_sgs - 1, i) 488 if (sg->length % max) 489 return -EINVAL; 490 } 491 492 /* the I/O buffer must be mapped/unmapped, except when length=0 */ 493 if (urb->transfer_buffer_length > INT_MAX) 494 return -EMSGSIZE; 495 496 /* 497 * stuff that drivers shouldn't do, but which shouldn't 498 * cause problems in HCDs if they get it wrong. 499 */ 500 501 /* Check that the pipe's type matches the endpoint's type */ 502 if (usb_pipe_type_check(urb->dev, urb->pipe)) 503 dev_WARN(&dev->dev, "BOGUS urb xfer, pipe %x != type %x\n", 504 usb_pipetype(urb->pipe), pipetypes[xfertype]); 505 506 /* Check against a simple/standard policy */ 507 allowed = (URB_NO_TRANSFER_DMA_MAP | URB_NO_INTERRUPT | URB_DIR_MASK | 508 URB_FREE_BUFFER); 509 switch (xfertype) { 510 case USB_ENDPOINT_XFER_BULK: 511 case USB_ENDPOINT_XFER_INT: 512 if (is_out) 513 allowed |= URB_ZERO_PACKET; 514 fallthrough; 515 default: /* all non-iso endpoints */ 516 if (!is_out) 517 allowed |= URB_SHORT_NOT_OK; 518 break; 519 case USB_ENDPOINT_XFER_ISOC: 520 allowed |= URB_ISO_ASAP; 521 break; 522 } 523 allowed &= urb->transfer_flags; 524 525 /* warn if submitter gave bogus flags */ 526 if (allowed != urb->transfer_flags) 527 dev_WARN(&dev->dev, "BOGUS urb flags, %x --> %x\n", 528 urb->transfer_flags, allowed); 529 530 /* 531 * Force periodic transfer intervals to be legal values that are 532 * a power of two (so HCDs don't need to). 533 * 534 * FIXME want bus->{intr,iso}_sched_horizon values here. Each HC 535 * supports different values... this uses EHCI/UHCI defaults (and 536 * EHCI can use smaller non-default values). 537 */ 538 switch (xfertype) { 539 case USB_ENDPOINT_XFER_ISOC: 540 case USB_ENDPOINT_XFER_INT: 541 /* too small? */ 542 if (urb->interval <= 0) 543 return -EINVAL; 544 545 /* too big? */ 546 switch (dev->speed) { 547 case USB_SPEED_SUPER_PLUS: 548 case USB_SPEED_SUPER: /* units are 125us */ 549 /* Handle up to 2^(16-1) microframes */ 550 if (urb->interval > (1 << 15)) 551 return -EINVAL; 552 max = 1 << 15; 553 break; 554 case USB_SPEED_HIGH: /* units are microframes */ 555 /* NOTE usb handles 2^15 */ 556 if (urb->interval > (1024 * 8)) 557 urb->interval = 1024 * 8; 558 max = 1024 * 8; 559 break; 560 case USB_SPEED_FULL: /* units are frames/msec */ 561 case USB_SPEED_LOW: 562 if (xfertype == USB_ENDPOINT_XFER_INT) { 563 if (urb->interval > 255) 564 return -EINVAL; 565 /* NOTE ohci only handles up to 32 */ 566 max = 128; 567 } else { 568 if (urb->interval > 1024) 569 urb->interval = 1024; 570 /* NOTE usb and ohci handle up to 2^15 */ 571 max = 1024; 572 } 573 break; 574 default: 575 return -EINVAL; 576 } 577 /* Round down to a power of 2, no more than max */ 578 urb->interval = min(max, 1 << ilog2(urb->interval)); 579 } 580 581 return usb_hcd_submit_urb(urb, mem_flags); 582} 583EXPORT_SYMBOL_GPL(usb_submit_urb); 584 585/*-------------------------------------------------------------------*/ 586 587/** 588 * usb_unlink_urb - abort/cancel a transfer request for an endpoint 589 * @urb: pointer to urb describing a previously submitted request, 590 * may be NULL 591 * 592 * This routine cancels an in-progress request. URBs complete only once 593 * per submission, and may be canceled only once per submission. 594 * Successful cancellation means termination of @urb will be expedited 595 * and the completion handler will be called with a status code 596 * indicating that the request has been canceled (rather than any other 597 * code). 598 * 599 * Drivers should not call this routine or related routines, such as 600 * usb_kill_urb() or usb_unlink_anchored_urbs(), after their disconnect 601 * method has returned. The disconnect function should synchronize with 602 * a driver's I/O routines to insure that all URB-related activity has 603 * completed before it returns. 604 * 605 * This request is asynchronous, however the HCD might call the ->complete() 606 * callback during unlink. Therefore when drivers call usb_unlink_urb(), they 607 * must not hold any locks that may be taken by the completion function. 608 * Success is indicated by returning -EINPROGRESS, at which time the URB will 609 * probably not yet have been given back to the device driver. When it is 610 * eventually called, the completion function will see @urb->status == 611 * -ECONNRESET. 612 * Failure is indicated by usb_unlink_urb() returning any other value. 613 * Unlinking will fail when @urb is not currently "linked" (i.e., it was 614 * never submitted, or it was unlinked before, or the hardware is already 615 * finished with it), even if the completion handler has not yet run. 616 * 617 * The URB must not be deallocated while this routine is running. In 618 * particular, when a driver calls this routine, it must insure that the 619 * completion handler cannot deallocate the URB. 620 * 621 * Return: -EINPROGRESS on success. See description for other values on 622 * failure. 623 * 624 * Unlinking and Endpoint Queues: 625 * 626 * [The behaviors and guarantees described below do not apply to virtual 627 * root hubs but only to endpoint queues for physical USB devices.] 628 * 629 * Host Controller Drivers (HCDs) place all the URBs for a particular 630 * endpoint in a queue. Normally the queue advances as the controller 631 * hardware processes each request. But when an URB terminates with an 632 * error its queue generally stops (see below), at least until that URB's 633 * completion routine returns. It is guaranteed that a stopped queue 634 * will not restart until all its unlinked URBs have been fully retired, 635 * with their completion routines run, even if that's not until some time 636 * after the original completion handler returns. The same behavior and 637 * guarantee apply when an URB terminates because it was unlinked. 638 * 639 * Bulk and interrupt endpoint queues are guaranteed to stop whenever an 640 * URB terminates with any sort of error, including -ECONNRESET, -ENOENT, 641 * and -EREMOTEIO. Control endpoint queues behave the same way except 642 * that they are not guaranteed to stop for -EREMOTEIO errors. Queues 643 * for isochronous endpoints are treated differently, because they must 644 * advance at fixed rates. Such queues do not stop when an URB 645 * encounters an error or is unlinked. An unlinked isochronous URB may 646 * leave a gap in the stream of packets; it is undefined whether such 647 * gaps can be filled in. 648 * 649 * Note that early termination of an URB because a short packet was 650 * received will generate a -EREMOTEIO error if and only if the 651 * URB_SHORT_NOT_OK flag is set. By setting this flag, USB device 652 * drivers can build deep queues for large or complex bulk transfers 653 * and clean them up reliably after any sort of aborted transfer by 654 * unlinking all pending URBs at the first fault. 655 * 656 * When a control URB terminates with an error other than -EREMOTEIO, it 657 * is quite likely that the status stage of the transfer will not take 658 * place. 659 */ 660int usb_unlink_urb(struct urb *urb) 661{ 662 if (!urb) 663 return -EINVAL; 664 if (!urb->dev) 665 return -ENODEV; 666 if (!urb->ep) 667 return -EIDRM; 668 return usb_hcd_unlink_urb(urb, -ECONNRESET); 669} 670EXPORT_SYMBOL_GPL(usb_unlink_urb); 671 672/** 673 * usb_kill_urb - cancel a transfer request and wait for it to finish 674 * @urb: pointer to URB describing a previously submitted request, 675 * may be NULL 676 * 677 * This routine cancels an in-progress request. It is guaranteed that 678 * upon return all completion handlers will have finished and the URB 679 * will be totally idle and available for reuse. These features make 680 * this an ideal way to stop I/O in a disconnect() callback or close() 681 * function. If the request has not already finished or been unlinked 682 * the completion handler will see urb->status == -ENOENT. 683 * 684 * While the routine is running, attempts to resubmit the URB will fail 685 * with error -EPERM. Thus even if the URB's completion handler always 686 * tries to resubmit, it will not succeed and the URB will become idle. 687 * 688 * The URB must not be deallocated while this routine is running. In 689 * particular, when a driver calls this routine, it must insure that the 690 * completion handler cannot deallocate the URB. 691 * 692 * This routine may not be used in an interrupt context (such as a bottom 693 * half or a completion handler), or when holding a spinlock, or in other 694 * situations where the caller can't schedule(). 695 * 696 * This routine should not be called by a driver after its disconnect 697 * method has returned. 698 */ 699void usb_kill_urb(struct urb *urb) 700{ 701 might_sleep(); 702 if (!(urb && urb->dev && urb->ep)) 703 return; 704 atomic_inc(&urb->reject); 705 /* 706 * Order the write of urb->reject above before the read 707 * of urb->use_count below. Pairs with the barriers in 708 * __usb_hcd_giveback_urb() and usb_hcd_submit_urb(). 709 */ 710 smp_mb__after_atomic(); 711 712 usb_hcd_unlink_urb(urb, -ENOENT); 713 wait_event(usb_kill_urb_queue, atomic_read(&urb->use_count) == 0); 714 715 atomic_dec(&urb->reject); 716} 717EXPORT_SYMBOL_GPL(usb_kill_urb); 718 719/** 720 * usb_poison_urb - reliably kill a transfer and prevent further use of an URB 721 * @urb: pointer to URB describing a previously submitted request, 722 * may be NULL 723 * 724 * This routine cancels an in-progress request. It is guaranteed that 725 * upon return all completion handlers will have finished and the URB 726 * will be totally idle and cannot be reused. These features make 727 * this an ideal way to stop I/O in a disconnect() callback. 728 * If the request has not already finished or been unlinked 729 * the completion handler will see urb->status == -ENOENT. 730 * 731 * After and while the routine runs, attempts to resubmit the URB will fail 732 * with error -EPERM. Thus even if the URB's completion handler always 733 * tries to resubmit, it will not succeed and the URB will become idle. 734 * 735 * The URB must not be deallocated while this routine is running. In 736 * particular, when a driver calls this routine, it must insure that the 737 * completion handler cannot deallocate the URB. 738 * 739 * This routine may not be used in an interrupt context (such as a bottom 740 * half or a completion handler), or when holding a spinlock, or in other 741 * situations where the caller can't schedule(). 742 * 743 * This routine should not be called by a driver after its disconnect 744 * method has returned. 745 */ 746void usb_poison_urb(struct urb *urb) 747{ 748 might_sleep(); 749 if (!urb) 750 return; 751 atomic_inc(&urb->reject); 752 /* 753 * Order the write of urb->reject above before the read 754 * of urb->use_count below. Pairs with the barriers in 755 * __usb_hcd_giveback_urb() and usb_hcd_submit_urb(). 756 */ 757 smp_mb__after_atomic(); 758 759 if (!urb->dev || !urb->ep) 760 return; 761 762 usb_hcd_unlink_urb(urb, -ENOENT); 763 wait_event(usb_kill_urb_queue, atomic_read(&urb->use_count) == 0); 764} 765EXPORT_SYMBOL_GPL(usb_poison_urb); 766 767void usb_unpoison_urb(struct urb *urb) 768{ 769 if (!urb) 770 return; 771 772 atomic_dec(&urb->reject); 773} 774EXPORT_SYMBOL_GPL(usb_unpoison_urb); 775 776/** 777 * usb_block_urb - reliably prevent further use of an URB 778 * @urb: pointer to URB to be blocked, may be NULL 779 * 780 * After the routine has run, attempts to resubmit the URB will fail 781 * with error -EPERM. Thus even if the URB's completion handler always 782 * tries to resubmit, it will not succeed and the URB will become idle. 783 * 784 * The URB must not be deallocated while this routine is running. In 785 * particular, when a driver calls this routine, it must insure that the 786 * completion handler cannot deallocate the URB. 787 */ 788void usb_block_urb(struct urb *urb) 789{ 790 if (!urb) 791 return; 792 793 atomic_inc(&urb->reject); 794} 795EXPORT_SYMBOL_GPL(usb_block_urb); 796 797/** 798 * usb_kill_anchored_urbs - kill all URBs associated with an anchor 799 * @anchor: anchor the requests are bound to 800 * 801 * This kills all outstanding URBs starting from the back of the queue, 802 * with guarantee that no completer callbacks will take place from the 803 * anchor after this function returns. 804 * 805 * This routine should not be called by a driver after its disconnect 806 * method has returned. 807 */ 808void usb_kill_anchored_urbs(struct usb_anchor *anchor) 809{ 810 struct urb *victim; 811 int surely_empty; 812 813 do { 814 spin_lock_irq(&anchor->lock); 815 while (!list_empty(&anchor->urb_list)) { 816 victim = list_entry(anchor->urb_list.prev, 817 struct urb, anchor_list); 818 /* make sure the URB isn't freed before we kill it */ 819 usb_get_urb(victim); 820 spin_unlock_irq(&anchor->lock); 821 /* this will unanchor the URB */ 822 usb_kill_urb(victim); 823 usb_put_urb(victim); 824 spin_lock_irq(&anchor->lock); 825 } 826 surely_empty = usb_anchor_check_wakeup(anchor); 827 828 spin_unlock_irq(&anchor->lock); 829 cpu_relax(); 830 } while (!surely_empty); 831} 832EXPORT_SYMBOL_GPL(usb_kill_anchored_urbs); 833 834 835/** 836 * usb_poison_anchored_urbs - cease all traffic from an anchor 837 * @anchor: anchor the requests are bound to 838 * 839 * this allows all outstanding URBs to be poisoned starting 840 * from the back of the queue. Newly added URBs will also be 841 * poisoned 842 * 843 * This routine should not be called by a driver after its disconnect 844 * method has returned. 845 */ 846void usb_poison_anchored_urbs(struct usb_anchor *anchor) 847{ 848 struct urb *victim; 849 int surely_empty; 850 851 do { 852 spin_lock_irq(&anchor->lock); 853 anchor->poisoned = 1; 854 while (!list_empty(&anchor->urb_list)) { 855 victim = list_entry(anchor->urb_list.prev, 856 struct urb, anchor_list); 857 /* make sure the URB isn't freed before we kill it */ 858 usb_get_urb(victim); 859 spin_unlock_irq(&anchor->lock); 860 /* this will unanchor the URB */ 861 usb_poison_urb(victim); 862 usb_put_urb(victim); 863 spin_lock_irq(&anchor->lock); 864 } 865 surely_empty = usb_anchor_check_wakeup(anchor); 866 867 spin_unlock_irq(&anchor->lock); 868 cpu_relax(); 869 } while (!surely_empty); 870} 871EXPORT_SYMBOL_GPL(usb_poison_anchored_urbs); 872 873/** 874 * usb_unpoison_anchored_urbs - let an anchor be used successfully again 875 * @anchor: anchor the requests are bound to 876 * 877 * Reverses the effect of usb_poison_anchored_urbs 878 * the anchor can be used normally after it returns 879 */ 880void usb_unpoison_anchored_urbs(struct usb_anchor *anchor) 881{ 882 unsigned long flags; 883 struct urb *lazarus; 884 885 spin_lock_irqsave(&anchor->lock, flags); 886 list_for_each_entry(lazarus, &anchor->urb_list, anchor_list) { 887 usb_unpoison_urb(lazarus); 888 } 889 anchor->poisoned = 0; 890 spin_unlock_irqrestore(&anchor->lock, flags); 891} 892EXPORT_SYMBOL_GPL(usb_unpoison_anchored_urbs); 893/** 894 * usb_unlink_anchored_urbs - asynchronously cancel transfer requests en masse 895 * @anchor: anchor the requests are bound to 896 * 897 * this allows all outstanding URBs to be unlinked starting 898 * from the back of the queue. This function is asynchronous. 899 * The unlinking is just triggered. It may happen after this 900 * function has returned. 901 * 902 * This routine should not be called by a driver after its disconnect 903 * method has returned. 904 */ 905void usb_unlink_anchored_urbs(struct usb_anchor *anchor) 906{ 907 struct urb *victim; 908 909 while ((victim = usb_get_from_anchor(anchor)) != NULL) { 910 usb_unlink_urb(victim); 911 usb_put_urb(victim); 912 } 913} 914EXPORT_SYMBOL_GPL(usb_unlink_anchored_urbs); 915 916/** 917 * usb_anchor_suspend_wakeups 918 * @anchor: the anchor you want to suspend wakeups on 919 * 920 * Call this to stop the last urb being unanchored from waking up any 921 * usb_wait_anchor_empty_timeout waiters. This is used in the hcd urb give- 922 * back path to delay waking up until after the completion handler has run. 923 */ 924void usb_anchor_suspend_wakeups(struct usb_anchor *anchor) 925{ 926 if (anchor) 927 atomic_inc(&anchor->suspend_wakeups); 928} 929EXPORT_SYMBOL_GPL(usb_anchor_suspend_wakeups); 930 931/** 932 * usb_anchor_resume_wakeups 933 * @anchor: the anchor you want to resume wakeups on 934 * 935 * Allow usb_wait_anchor_empty_timeout waiters to be woken up again, and 936 * wake up any current waiters if the anchor is empty. 937 */ 938void usb_anchor_resume_wakeups(struct usb_anchor *anchor) 939{ 940 if (!anchor) 941 return; 942 943 atomic_dec(&anchor->suspend_wakeups); 944 if (usb_anchor_check_wakeup(anchor)) 945 wake_up(&anchor->wait); 946} 947EXPORT_SYMBOL_GPL(usb_anchor_resume_wakeups); 948 949/** 950 * usb_wait_anchor_empty_timeout - wait for an anchor to be unused 951 * @anchor: the anchor you want to become unused 952 * @timeout: how long you are willing to wait in milliseconds 953 * 954 * Call this is you want to be sure all an anchor's 955 * URBs have finished 956 * 957 * Return: Non-zero if the anchor became unused. Zero on timeout. 958 */ 959int usb_wait_anchor_empty_timeout(struct usb_anchor *anchor, 960 unsigned int timeout) 961{ 962 return wait_event_timeout(anchor->wait, 963 usb_anchor_check_wakeup(anchor), 964 msecs_to_jiffies(timeout)); 965} 966EXPORT_SYMBOL_GPL(usb_wait_anchor_empty_timeout); 967 968/** 969 * usb_get_from_anchor - get an anchor's oldest urb 970 * @anchor: the anchor whose urb you want 971 * 972 * This will take the oldest urb from an anchor, 973 * unanchor and return it 974 * 975 * Return: The oldest urb from @anchor, or %NULL if @anchor has no 976 * urbs associated with it. 977 */ 978struct urb *usb_get_from_anchor(struct usb_anchor *anchor) 979{ 980 struct urb *victim; 981 unsigned long flags; 982 983 spin_lock_irqsave(&anchor->lock, flags); 984 if (!list_empty(&anchor->urb_list)) { 985 victim = list_entry(anchor->urb_list.next, struct urb, 986 anchor_list); 987 usb_get_urb(victim); 988 __usb_unanchor_urb(victim, anchor); 989 } else { 990 victim = NULL; 991 } 992 spin_unlock_irqrestore(&anchor->lock, flags); 993 994 return victim; 995} 996 997EXPORT_SYMBOL_GPL(usb_get_from_anchor); 998 999/** 1000 * usb_scuttle_anchored_urbs - unanchor all an anchor's urbs 1001 * @anchor: the anchor whose urbs you want to unanchor 1002 * 1003 * use this to get rid of all an anchor's urbs 1004 */ 1005void usb_scuttle_anchored_urbs(struct usb_anchor *anchor) 1006{ 1007 struct urb *victim; 1008 unsigned long flags; 1009 int surely_empty; 1010 1011 do { 1012 spin_lock_irqsave(&anchor->lock, flags); 1013 while (!list_empty(&anchor->urb_list)) { 1014 victim = list_entry(anchor->urb_list.prev, 1015 struct urb, anchor_list); 1016 __usb_unanchor_urb(victim, anchor); 1017 } 1018 surely_empty = usb_anchor_check_wakeup(anchor); 1019 1020 spin_unlock_irqrestore(&anchor->lock, flags); 1021 cpu_relax(); 1022 } while (!surely_empty); 1023} 1024 1025EXPORT_SYMBOL_GPL(usb_scuttle_anchored_urbs); 1026 1027/** 1028 * usb_anchor_empty - is an anchor empty 1029 * @anchor: the anchor you want to query 1030 * 1031 * Return: 1 if the anchor has no urbs associated with it. 1032 */ 1033int usb_anchor_empty(struct usb_anchor *anchor) 1034{ 1035 return list_empty(&anchor->urb_list); 1036} 1037 1038EXPORT_SYMBOL_GPL(usb_anchor_empty); 1039 1040