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
19 static 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 */
43 void 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->urb_list);
49 INIT_LIST_HEAD(&urb->anchor_list);
50 }
51 }
52 EXPORT_SYMBOL_GPL(usb_init_urb);
53
54 /**
55 * usb_alloc_urb - creates a new urb for a USB driver to use
56 * @iso_packets: number of iso packets for this urb
57 * @mem_flags: the type of memory to allocate, see kmalloc() for a list of
58 * valid options for this.
59 *
60 * Creates an urb for the USB driver to use, initializes a few internal
61 * structures, increments the usage counter, and returns a pointer to it.
62 *
63 * If the driver want to use this urb for interrupt, control, or bulk
64 * endpoints, pass '0' as the number of iso packets.
65 *
66 * The driver must call usb_free_urb() when it is finished with the urb.
67 *
68 * Return: A pointer to the new urb, or %NULL if no memory is available.
69 */
70 struct urb *usb_alloc_urb(int iso_packets, gfp_t mem_flags)
71 {
72 struct urb *urb;
73
74 urb = kmalloc(struct_size(urb, iso_frame_desc, iso_packets),
75 mem_flags);
76 if (!urb)
77 return NULL;
78 usb_init_urb(urb);
79 return urb;
80 }
81 EXPORT_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 */
93 void usb_free_urb(struct urb *urb)
94 {
95 if (urb)
96 kref_put(&urb->kref, urb_destroy);
97 }
98 EXPORT_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 */
110 struct urb *usb_get_urb(struct urb *urb)
111 {
112 if (urb)
113 kref_get(&urb->kref);
114 return urb;
115 }
116 EXPORT_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 */
126 void 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 }
140 EXPORT_SYMBOL_GPL(usb_anchor_urb);
141
142 static 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 */
149 static 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 */
164 void 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 }
186 EXPORT_SYMBOL_GPL(usb_unanchor_urb);
187
188 /*-------------------------------------------------------------------*/
189
190 static 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 */
202 int 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 }
213 EXPORT_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 */
352 int 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 }
572 EXPORT_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 */
649 int 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 }
659 EXPORT_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 */
688 void 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 }
700 EXPORT_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 */
729 void 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 }
742 EXPORT_SYMBOL_GPL(usb_poison_urb);
743
744 void usb_unpoison_urb(struct urb *urb)
745 {
746 if (!urb)
747 return;
748
749 atomic_dec(&urb->reject);
750 }
751 EXPORT_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 */
765 void usb_block_urb(struct urb *urb)
766 {
767 if (!urb)
768 return;
769
770 atomic_inc(&urb->reject);
771 }
772 EXPORT_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 */
784 void 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 }
802 EXPORT_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 */
816 void 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 }
835 EXPORT_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 */
844 void 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 }
856 EXPORT_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 */
869 void 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 }
878 EXPORT_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 */
888 void usb_anchor_suspend_wakeups(struct usb_anchor *anchor)
889 {
890 if (anchor)
891 atomic_inc(&anchor->suspend_wakeups);
892 }
893 EXPORT_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 */
902 void 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 }
911 EXPORT_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 */
923 int 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 }
930 EXPORT_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 */
942 struct 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
961 EXPORT_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 */
969 void 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
983 EXPORT_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 */
991 int usb_anchor_empty(struct usb_anchor *anchor)
992 {
993 return list_empty(&anchor->urb_list);
994 }
995
996 EXPORT_SYMBOL_GPL(usb_anchor_empty);
997