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