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urb.c
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linux-6.19.14/drivers/usb/core/urb.c
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 bool is_eusb2_isoch_double; 376 377 if (!urb || !urb->complete) 378 return -EINVAL; 379 if (urb->hcpriv) { 380 WARN_ONCE(1, "URB %p submitted while active\n", urb); 381 return -EBUSY; 382 } 383 384 dev = urb->dev; 385 if ((!dev) || (dev->state < USB_STATE_UNAUTHENTICATED)) 386 return -ENODEV; 387 388 /* For now, get the endpoint from the pipe. Eventually drivers 389 * will be required to set urb->ep directly and we will eliminate 390 * urb->pipe. 391 */ 392 ep = usb_pipe_endpoint(dev, urb->pipe); 393 if (!ep) 394 return -ENOENT; 395 396 urb->ep = ep; 397 urb->status = -EINPROGRESS; 398 urb->actual_length = 0; 399 400 /* Lots of sanity checks, so HCDs can rely on clean data 401 * and don't need to duplicate tests 402 */ 403 xfertype = usb_endpoint_type(&ep->desc); 404 if (xfertype == USB_ENDPOINT_XFER_CONTROL) { 405 struct usb_ctrlrequest *setup = 406 (struct usb_ctrlrequest *) urb->setup_packet; 407 408 if (!setup) 409 return -ENOEXEC; 410 is_out = !(setup->bRequestType & USB_DIR_IN) || 411 !setup->wLength; 412 dev_WARN_ONCE(&dev->dev, (usb_pipeout(urb->pipe) != is_out), 413 "BOGUS control dir, pipe %x doesn't match bRequestType %x\n", 414 urb->pipe, setup->bRequestType); 415 if (le16_to_cpu(setup->wLength) != urb->transfer_buffer_length) { 416 dev_dbg(&dev->dev, "BOGUS control len %d doesn't match transfer length %d\n", 417 le16_to_cpu(setup->wLength), 418 urb->transfer_buffer_length); 419 return -EBADR; 420 } 421 } else { 422 is_out = usb_endpoint_dir_out(&ep->desc); 423 } 424 425 /* Clear the internal flags and cache the direction for later use */ 426 urb->transfer_flags &= ~(URB_DIR_MASK | URB_DMA_MAP_SINGLE | 427 URB_DMA_MAP_PAGE | URB_DMA_MAP_SG | URB_MAP_LOCAL | 428 URB_SETUP_MAP_SINGLE | URB_SETUP_MAP_LOCAL | 429 URB_DMA_SG_COMBINED); 430 urb->transfer_flags |= (is_out ? URB_DIR_OUT : URB_DIR_IN); 431 kmsan_handle_urb(urb, is_out); 432 433 if (xfertype != USB_ENDPOINT_XFER_CONTROL && 434 dev->state < USB_STATE_CONFIGURED) 435 return -ENODEV; 436 437 max = usb_endpoint_maxp(&ep->desc); 438 is_eusb2_isoch_double = usb_endpoint_is_hs_isoc_double(dev, ep); 439 if (!max && !is_eusb2_isoch_double) { 440 dev_dbg(&dev->dev, 441 "bogus endpoint ep%d%s in %s (bad maxpacket %d)\n", 442 usb_endpoint_num(&ep->desc), is_out ? "out" : "in", 443 __func__, max); 444 return -EMSGSIZE; 445 } 446 447 /* periodic transfers limit size per frame/uframe, 448 * but drivers only control those sizes for ISO. 449 * while we're checking, initialize return status. 450 */ 451 if (xfertype == USB_ENDPOINT_XFER_ISOC) { 452 int n, len; 453 454 /* SuperSpeed isoc endpoints have up to 16 bursts of up to 455 * 3 packets each 456 */ 457 if (dev->speed >= USB_SPEED_SUPER) { 458 int burst = 1 + ep->ss_ep_comp.bMaxBurst; 459 int mult = USB_SS_MULT(ep->ss_ep_comp.bmAttributes); 460 max *= burst; 461 max *= mult; 462 } 463 464 if (dev->speed == USB_SPEED_SUPER_PLUS && 465 USB_SS_SSP_ISOC_COMP(ep->ss_ep_comp.bmAttributes)) { 466 struct usb_ssp_isoc_ep_comp_descriptor *isoc_ep_comp; 467 468 isoc_ep_comp = &ep->ssp_isoc_ep_comp; 469 max = le32_to_cpu(isoc_ep_comp->dwBytesPerInterval); 470 } 471 472 /* High speed, 1-3 packets/uframe, max 6 for eUSB2 double bw */ 473 if (dev->speed == USB_SPEED_HIGH) { 474 if (is_eusb2_isoch_double) 475 max = le32_to_cpu(ep->eusb2_isoc_ep_comp.dwBytesPerInterval); 476 else 477 max *= usb_endpoint_maxp_mult(&ep->desc); 478 } 479 480 if (urb->number_of_packets <= 0) 481 return -EINVAL; 482 for (n = 0; n < urb->number_of_packets; n++) { 483 len = urb->iso_frame_desc[n].length; 484 if (len < 0 || len > max) 485 return -EMSGSIZE; 486 urb->iso_frame_desc[n].status = -EXDEV; 487 urb->iso_frame_desc[n].actual_length = 0; 488 } 489 } else if (urb->num_sgs && !urb->dev->bus->no_sg_constraint) { 490 struct scatterlist *sg; 491 int i; 492 493 for_each_sg(urb->sg, sg, urb->num_sgs - 1, i) 494 if (sg->length % max) 495 return -EINVAL; 496 } 497 498 /* the I/O buffer must be mapped/unmapped, except when length=0 */ 499 if (urb->transfer_buffer_length > INT_MAX) 500 return -EMSGSIZE; 501 502 /* 503 * stuff that drivers shouldn't do, but which shouldn't 504 * cause problems in HCDs if they get it wrong. 505 */ 506 507 /* Check that the pipe's type matches the endpoint's type */ 508 if (usb_pipe_type_check(urb->dev, urb->pipe)) 509 dev_warn_once(&dev->dev, "BOGUS urb xfer, pipe %x != type %x\n", 510 usb_pipetype(urb->pipe), pipetypes[xfertype]); 511 512 /* Check against a simple/standard policy */ 513 allowed = (URB_NO_TRANSFER_DMA_MAP | URB_NO_INTERRUPT | URB_DIR_MASK | 514 URB_FREE_BUFFER); 515 switch (xfertype) { 516 case USB_ENDPOINT_XFER_BULK: 517 case USB_ENDPOINT_XFER_INT: 518 if (is_out) 519 allowed |= URB_ZERO_PACKET; 520 fallthrough; 521 default: /* all non-iso endpoints */ 522 if (!is_out) 523 allowed |= URB_SHORT_NOT_OK; 524 break; 525 case USB_ENDPOINT_XFER_ISOC: 526 allowed |= URB_ISO_ASAP; 527 break; 528 } 529 allowed &= urb->transfer_flags; 530 531 /* warn if submitter gave bogus flags */ 532 if (allowed != urb->transfer_flags) 533 dev_WARN(&dev->dev, "BOGUS urb flags, %x --> %x\n", 534 urb->transfer_flags, allowed); 535 536 /* 537 * Force periodic transfer intervals to be legal values that are 538 * a power of two (so HCDs don't need to). 539 * 540 * FIXME want bus->{intr,iso}_sched_horizon values here. Each HC 541 * supports different values... this uses EHCI/UHCI defaults (and 542 * EHCI can use smaller non-default values). 543 */ 544 switch (xfertype) { 545 case USB_ENDPOINT_XFER_ISOC: 546 case USB_ENDPOINT_XFER_INT: 547 /* too small? */ 548 if (urb->interval <= 0) 549 return -EINVAL; 550 551 /* too big? */ 552 switch (dev->speed) { 553 case USB_SPEED_SUPER_PLUS: 554 case USB_SPEED_SUPER: /* units are 125us */ 555 /* Handle up to 2^(16-1) microframes */ 556 if (urb->interval > (1 << 15)) 557 return -EINVAL; 558 max = 1 << 15; 559 break; 560 case USB_SPEED_HIGH: /* units are microframes */ 561 /* NOTE usb handles 2^15 */ 562 if (urb->interval > (1024 * 8)) 563 urb->interval = 1024 * 8; 564 max = 1024 * 8; 565 break; 566 case USB_SPEED_FULL: /* units are frames/msec */ 567 case USB_SPEED_LOW: 568 if (xfertype == USB_ENDPOINT_XFER_INT) { 569 if (urb->interval > 255) 570 return -EINVAL; 571 /* NOTE ohci only handles up to 32 */ 572 max = 128; 573 } else { 574 if (urb->interval > 1024) 575 urb->interval = 1024; 576 /* NOTE usb and ohci handle up to 2^15 */ 577 max = 1024; 578 } 579 break; 580 default: 581 return -EINVAL; 582 } 583 /* Round down to a power of 2, no more than max */ 584 urb->interval = min(max, 1 << ilog2(urb->interval)); 585 } 586 587 return usb_hcd_submit_urb(urb, mem_flags); 588} 589EXPORT_SYMBOL_GPL(usb_submit_urb); 590 591/*-------------------------------------------------------------------*/ 592 593/** 594 * usb_unlink_urb - abort/cancel a transfer request for an endpoint 595 * @urb: pointer to urb describing a previously submitted request, 596 * may be NULL 597 * 598 * This routine cancels an in-progress request. URBs complete only once 599 * per submission, and may be canceled only once per submission. 600 * Successful cancellation means termination of @urb will be expedited 601 * and the completion handler will be called with a status code 602 * indicating that the request has been canceled (rather than any other 603 * code). 604 * 605 * Drivers should not call this routine or related routines, such as 606 * usb_kill_urb(), after their disconnect method has returned. The 607 * disconnect function should synchronize with a driver's I/O routines 608 * to insure that all URB-related activity has completed before it returns. 609 * 610 * This request is asynchronous, however the HCD might call the ->complete() 611 * callback during unlink. Therefore when drivers call usb_unlink_urb(), they 612 * must not hold any locks that may be taken by the completion function. 613 * Success is indicated by returning -EINPROGRESS, at which time the URB will 614 * probably not yet have been given back to the device driver. When it is 615 * eventually called, the completion function will see @urb->status == 616 * -ECONNRESET. 617 * Failure is indicated by usb_unlink_urb() returning any other value. 618 * Unlinking will fail when @urb is not currently "linked" (i.e., it was 619 * never submitted, or it was unlinked before, or the hardware is already 620 * finished with it), even if the completion handler has not yet run. 621 * 622 * The URB must not be deallocated while this routine is running. In 623 * particular, when a driver calls this routine, it must insure that the 624 * completion handler cannot deallocate the URB. 625 * 626 * Return: -EINPROGRESS on success. See description for other values on 627 * failure. 628 * 629 * Unlinking and Endpoint Queues: 630 * 631 * [The behaviors and guarantees described below do not apply to virtual 632 * root hubs but only to endpoint queues for physical USB devices.] 633 * 634 * Host Controller Drivers (HCDs) place all the URBs for a particular 635 * endpoint in a queue. Normally the queue advances as the controller 636 * hardware processes each request. But when an URB terminates with an 637 * error its queue generally stops (see below), at least until that URB's 638 * completion routine returns. It is guaranteed that a stopped queue 639 * will not restart until all its unlinked URBs have been fully retired, 640 * with their completion routines run, even if that's not until some time 641 * after the original completion handler returns. The same behavior and 642 * guarantee apply when an URB terminates because it was unlinked. 643 * 644 * Bulk and interrupt endpoint queues are guaranteed to stop whenever an 645 * URB terminates with any sort of error, including -ECONNRESET, -ENOENT, 646 * and -EREMOTEIO. Control endpoint queues behave the same way except 647 * that they are not guaranteed to stop for -EREMOTEIO errors. Queues 648 * for isochronous endpoints are treated differently, because they must 649 * advance at fixed rates. Such queues do not stop when an URB 650 * encounters an error or is unlinked. An unlinked isochronous URB may 651 * leave a gap in the stream of packets; it is undefined whether such 652 * gaps can be filled in. 653 * 654 * Note that early termination of an URB because a short packet was 655 * received will generate a -EREMOTEIO error if and only if the 656 * URB_SHORT_NOT_OK flag is set. By setting this flag, USB device 657 * drivers can build deep queues for large or complex bulk transfers 658 * and clean them up reliably after any sort of aborted transfer by 659 * unlinking all pending URBs at the first fault. 660 * 661 * When a control URB terminates with an error other than -EREMOTEIO, it 662 * is quite likely that the status stage of the transfer will not take 663 * place. 664 */ 665int usb_unlink_urb(struct urb *urb) 666{ 667 if (!urb) 668 return -EINVAL; 669 if (!urb->dev) 670 return -ENODEV; 671 if (!urb->ep) 672 return -EIDRM; 673 return usb_hcd_unlink_urb(urb, -ECONNRESET); 674} 675EXPORT_SYMBOL_GPL(usb_unlink_urb); 676 677/** 678 * usb_kill_urb - cancel a transfer request and wait for it to finish 679 * @urb: pointer to URB describing a previously submitted request, 680 * may be NULL 681 * 682 * This routine cancels an in-progress request. It is guaranteed that 683 * upon return all completion handlers will have finished and the URB 684 * will be totally idle and available for reuse. These features make 685 * this an ideal way to stop I/O in a disconnect() callback or close() 686 * function. If the request has not already finished or been unlinked 687 * the completion handler will see urb->status == -ENOENT. 688 * 689 * While the routine is running, attempts to resubmit the URB will fail 690 * with error -EPERM. Thus even if the URB's completion handler always 691 * tries to resubmit, it will not succeed and the URB will become idle. 692 * 693 * The URB must not be deallocated while this routine is running. In 694 * particular, when a driver calls this routine, it must insure that the 695 * completion handler cannot deallocate the URB. 696 * 697 * This routine may not be used in an interrupt context (such as a bottom 698 * half or a completion handler), or when holding a spinlock, or in other 699 * situations where the caller can't schedule(). 700 * 701 * This routine should not be called by a driver after its disconnect 702 * method has returned. 703 */ 704void usb_kill_urb(struct urb *urb) 705{ 706 might_sleep(); 707 if (!(urb && urb->dev && urb->ep)) 708 return; 709 atomic_inc(&urb->reject); 710 /* 711 * Order the write of urb->reject above before the read 712 * of urb->use_count below. Pairs with the barriers in 713 * __usb_hcd_giveback_urb() and usb_hcd_submit_urb(). 714 */ 715 smp_mb__after_atomic(); 716 717 usb_hcd_unlink_urb(urb, -ENOENT); 718 wait_event(usb_kill_urb_queue, atomic_read(&urb->use_count) == 0); 719 720 atomic_dec(&urb->reject); 721} 722EXPORT_SYMBOL_GPL(usb_kill_urb); 723 724/** 725 * usb_poison_urb - reliably kill a transfer and prevent further use of an URB 726 * @urb: pointer to URB describing a previously submitted request, 727 * may be NULL 728 * 729 * This routine cancels an in-progress request. It is guaranteed that 730 * upon return all completion handlers will have finished and the URB 731 * will be totally idle and cannot be reused. These features make 732 * this an ideal way to stop I/O in a disconnect() callback. 733 * If the request has not already finished or been unlinked 734 * the completion handler will see urb->status == -ENOENT. 735 * 736 * After and while the routine runs, attempts to resubmit the URB will fail 737 * with error -EPERM. Thus even if the URB's completion handler always 738 * tries to resubmit, it will not succeed and the URB will become idle. 739 * 740 * The URB must not be deallocated while this routine is running. In 741 * particular, when a driver calls this routine, it must insure that the 742 * completion handler cannot deallocate the URB. 743 * 744 * This routine may not be used in an interrupt context (such as a bottom 745 * half or a completion handler), or when holding a spinlock, or in other 746 * situations where the caller can't schedule(). 747 * 748 * This routine should not be called by a driver after its disconnect 749 * method has returned. 750 */ 751void usb_poison_urb(struct urb *urb) 752{ 753 might_sleep(); 754 if (!urb) 755 return; 756 atomic_inc(&urb->reject); 757 /* 758 * Order the write of urb->reject above before the read 759 * of urb->use_count below. Pairs with the barriers in 760 * __usb_hcd_giveback_urb() and usb_hcd_submit_urb(). 761 */ 762 smp_mb__after_atomic(); 763 764 if (!urb->dev || !urb->ep) 765 return; 766 767 usb_hcd_unlink_urb(urb, -ENOENT); 768 wait_event(usb_kill_urb_queue, atomic_read(&urb->use_count) == 0); 769} 770EXPORT_SYMBOL_GPL(usb_poison_urb); 771 772void usb_unpoison_urb(struct urb *urb) 773{ 774 if (!urb) 775 return; 776 777 atomic_dec(&urb->reject); 778} 779EXPORT_SYMBOL_GPL(usb_unpoison_urb); 780 781/** 782 * usb_block_urb - reliably prevent further use of an URB 783 * @urb: pointer to URB to be blocked, may be NULL 784 * 785 * After the routine has run, attempts to resubmit the URB will fail 786 * with error -EPERM. Thus even if the URB's completion handler always 787 * tries to resubmit, it will not succeed and the URB will become idle. 788 * 789 * The URB must not be deallocated while this routine is running. In 790 * particular, when a driver calls this routine, it must insure that the 791 * completion handler cannot deallocate the URB. 792 */ 793void usb_block_urb(struct urb *urb) 794{ 795 if (!urb) 796 return; 797 798 atomic_inc(&urb->reject); 799} 800EXPORT_SYMBOL_GPL(usb_block_urb); 801 802/** 803 * usb_kill_anchored_urbs - kill all URBs associated with an anchor 804 * @anchor: anchor the requests are bound to 805 * 806 * This kills all outstanding URBs starting from the back of the queue, 807 * with guarantee that no completer callbacks will take place from the 808 * anchor after this function returns. 809 * 810 * This routine should not be called by a driver after its disconnect 811 * method has returned. 812 */ 813void usb_kill_anchored_urbs(struct usb_anchor *anchor) 814{ 815 struct urb *victim; 816 int surely_empty; 817 818 do { 819 spin_lock_irq(&anchor->lock); 820 while (!list_empty(&anchor->urb_list)) { 821 victim = list_entry(anchor->urb_list.prev, 822 struct urb, anchor_list); 823 /* make sure the URB isn't freed before we kill it */ 824 usb_get_urb(victim); 825 spin_unlock_irq(&anchor->lock); 826 /* this will unanchor the URB */ 827 usb_kill_urb(victim); 828 usb_put_urb(victim); 829 spin_lock_irq(&anchor->lock); 830 } 831 surely_empty = usb_anchor_check_wakeup(anchor); 832 833 spin_unlock_irq(&anchor->lock); 834 cpu_relax(); 835 } while (!surely_empty); 836} 837EXPORT_SYMBOL_GPL(usb_kill_anchored_urbs); 838 839 840/** 841 * usb_poison_anchored_urbs - cease all traffic from an anchor 842 * @anchor: anchor the requests are bound to 843 * 844 * this allows all outstanding URBs to be poisoned starting 845 * from the back of the queue. Newly added URBs will also be 846 * poisoned 847 * 848 * This routine should not be called by a driver after its disconnect 849 * method has returned. 850 */ 851void usb_poison_anchored_urbs(struct usb_anchor *anchor) 852{ 853 struct urb *victim; 854 int surely_empty; 855 856 do { 857 spin_lock_irq(&anchor->lock); 858 anchor->poisoned = 1; 859 while (!list_empty(&anchor->urb_list)) { 860 victim = list_entry(anchor->urb_list.prev, 861 struct urb, anchor_list); 862 /* make sure the URB isn't freed before we kill it */ 863 usb_get_urb(victim); 864 spin_unlock_irq(&anchor->lock); 865 /* this will unanchor the URB */ 866 usb_poison_urb(victim); 867 usb_put_urb(victim); 868 spin_lock_irq(&anchor->lock); 869 } 870 surely_empty = usb_anchor_check_wakeup(anchor); 871 872 spin_unlock_irq(&anchor->lock); 873 cpu_relax(); 874 } while (!surely_empty); 875} 876EXPORT_SYMBOL_GPL(usb_poison_anchored_urbs); 877 878/** 879 * usb_unpoison_anchored_urbs - let an anchor be used successfully again 880 * @anchor: anchor the requests are bound to 881 * 882 * Reverses the effect of usb_poison_anchored_urbs 883 * the anchor can be used normally after it returns 884 */ 885void usb_unpoison_anchored_urbs(struct usb_anchor *anchor) 886{ 887 unsigned long flags; 888 struct urb *lazarus; 889 890 spin_lock_irqsave(&anchor->lock, flags); 891 list_for_each_entry(lazarus, &anchor->urb_list, anchor_list) { 892 usb_unpoison_urb(lazarus); 893 } 894 anchor->poisoned = 0; 895 spin_unlock_irqrestore(&anchor->lock, flags); 896} 897EXPORT_SYMBOL_GPL(usb_unpoison_anchored_urbs); 898 899/** 900 * usb_anchor_suspend_wakeups 901 * @anchor: the anchor you want to suspend wakeups on 902 * 903 * Call this to stop the last urb being unanchored from waking up any 904 * usb_wait_anchor_empty_timeout waiters. This is used in the hcd urb give- 905 * back path to delay waking up until after the completion handler has run. 906 */ 907void usb_anchor_suspend_wakeups(struct usb_anchor *anchor) 908{ 909 if (anchor) 910 atomic_inc(&anchor->suspend_wakeups); 911} 912EXPORT_SYMBOL_GPL(usb_anchor_suspend_wakeups); 913 914/** 915 * usb_anchor_resume_wakeups 916 * @anchor: the anchor you want to resume wakeups on 917 * 918 * Allow usb_wait_anchor_empty_timeout waiters to be woken up again, and 919 * wake up any current waiters if the anchor is empty. 920 */ 921void usb_anchor_resume_wakeups(struct usb_anchor *anchor) 922{ 923 if (!anchor) 924 return; 925 926 atomic_dec(&anchor->suspend_wakeups); 927 if (usb_anchor_check_wakeup(anchor)) 928 wake_up(&anchor->wait); 929} 930EXPORT_SYMBOL_GPL(usb_anchor_resume_wakeups); 931 932/** 933 * usb_wait_anchor_empty_timeout - wait for an anchor to be unused 934 * @anchor: the anchor you want to become unused 935 * @timeout: how long you are willing to wait in milliseconds 936 * 937 * Call this is you want to be sure all an anchor's 938 * URBs have finished 939 * 940 * Return: Non-zero if the anchor became unused. Zero on timeout. 941 */ 942int usb_wait_anchor_empty_timeout(struct usb_anchor *anchor, 943 unsigned int timeout) 944{ 945 return wait_event_timeout(anchor->wait, 946 usb_anchor_check_wakeup(anchor), 947 msecs_to_jiffies(timeout)); 948} 949EXPORT_SYMBOL_GPL(usb_wait_anchor_empty_timeout); 950 951/** 952 * usb_get_from_anchor - get an anchor's oldest urb 953 * @anchor: the anchor whose urb you want 954 * 955 * This will take the oldest urb from an anchor, 956 * unanchor and return it 957 * 958 * Return: The oldest urb from @anchor, or %NULL if @anchor has no 959 * urbs associated with it. 960 */ 961struct urb *usb_get_from_anchor(struct usb_anchor *anchor) 962{ 963 struct urb *victim; 964 unsigned long flags; 965 966 spin_lock_irqsave(&anchor->lock, flags); 967 if (!list_empty(&anchor->urb_list)) { 968 victim = list_entry(anchor->urb_list.next, struct urb, 969 anchor_list); 970 usb_get_urb(victim); 971 __usb_unanchor_urb(victim, anchor); 972 } else { 973 victim = NULL; 974 } 975 spin_unlock_irqrestore(&anchor->lock, flags); 976 977 return victim; 978} 979 980EXPORT_SYMBOL_GPL(usb_get_from_anchor); 981 982/** 983 * usb_scuttle_anchored_urbs - unanchor all an anchor's urbs 984 * @anchor: the anchor whose urbs you want to unanchor 985 * 986 * use this to get rid of all an anchor's urbs 987 */ 988void usb_scuttle_anchored_urbs(struct usb_anchor *anchor) 989{ 990 struct urb *victim; 991 unsigned long flags; 992 int surely_empty; 993 994 do { 995 spin_lock_irqsave(&anchor->lock, flags); 996 while (!list_empty(&anchor->urb_list)) { 997 victim = list_entry(anchor->urb_list.prev, 998 struct urb, anchor_list); 999 __usb_unanchor_urb(victim, anchor); 1000 } 1001 surely_empty = usb_anchor_check_wakeup(anchor); 1002 1003 spin_unlock_irqrestore(&anchor->lock, flags); 1004 cpu_relax(); 1005 } while (!surely_empty); 1006} 1007 1008EXPORT_SYMBOL_GPL(usb_scuttle_anchored_urbs); 1009 1010/** 1011 * usb_anchor_empty - is an anchor empty 1012 * @anchor: the anchor you want to query 1013 * 1014 * Return: 1 if the anchor has no urbs associated with it. 1015 */ 1016int usb_anchor_empty(struct usb_anchor *anchor) 1017{ 1018 return list_empty(&anchor->urb_list); 1019} 1020 1021EXPORT_SYMBOL_GPL(usb_anchor_empty); 1022
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