1 // SPDX-License-Identifier: GPL-2.0
3 * Released under the GPLv2 only.
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>
16 #define to_urb(d) container_of(d, struct urb, kref)
19 static void urb_destroy(struct kref *kref)
21 struct urb *urb = to_urb(kref);
23 if (urb->transfer_flags & URB_FREE_BUFFER)
24 kfree(urb->transfer_buffer);
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
33 * Initializes a urb so that the USB subsystem can use it properly.
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.
41 * Only use this function if you _really_ understand what you are doing.
43 void usb_init_urb(struct urb *urb)
46 memset(urb, 0, sizeof(*urb));
47 kref_init(&urb->kref);
48 INIT_LIST_HEAD(&urb->anchor_list);
51 EXPORT_SYMBOL_GPL(usb_init_urb);
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.
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.
62 * If the driver want to use this urb for interrupt, control, or bulk
63 * endpoints, pass '0' as the number of iso packets.
65 * The driver must call usb_free_urb() when it is finished with the urb.
67 * Return: A pointer to the new urb, or %NULL if no memory is available.
69 struct urb *usb_alloc_urb(int iso_packets, gfp_t mem_flags)
73 urb = kmalloc(sizeof(struct urb) +
74 iso_packets * sizeof(struct usb_iso_packet_descriptor),
81 EXPORT_SYMBOL_GPL(usb_alloc_urb);
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
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.
90 * Note: The transfer buffer associated with the urb is not freed unless the
91 * URB_FREE_BUFFER transfer flag is set.
93 void usb_free_urb(struct urb *urb)
96 kref_put(&urb->kref, urb_destroy);
98 EXPORT_SYMBOL_GPL(usb_free_urb);
101 * usb_get_urb - increments the reference count of the urb
102 * @urb: pointer to the urb to modify, may be NULL
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
108 * Return: A pointer to the urb with the incremented reference counter.
110 struct urb *usb_get_urb(struct urb *urb)
113 kref_get(&urb->kref);
116 EXPORT_SYMBOL_GPL(usb_get_urb);
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
123 * This can be called to have access to URBs which are to be executed
124 * without bothering to track them
126 void usb_anchor_urb(struct urb *urb, struct usb_anchor *anchor)
130 spin_lock_irqsave(&anchor->lock, flags);
132 list_add_tail(&urb->anchor_list, &anchor->urb_list);
133 urb->anchor = anchor;
135 if (unlikely(anchor->poisoned))
136 atomic_inc(&urb->reject);
138 spin_unlock_irqrestore(&anchor->lock, flags);
140 EXPORT_SYMBOL_GPL(usb_anchor_urb);
142 static int usb_anchor_check_wakeup(struct usb_anchor *anchor)
144 return atomic_read(&anchor->suspend_wakeups) == 0 &&
145 list_empty(&anchor->urb_list);
148 /* Callers must hold anchor->lock */
149 static void __usb_unanchor_urb(struct urb *urb, struct usb_anchor *anchor)
152 list_del(&urb->anchor_list);
154 if (usb_anchor_check_wakeup(anchor))
155 wake_up(&anchor->wait);
159 * usb_unanchor_urb - unanchors an URB
160 * @urb: pointer to the urb to anchor
162 * Call this to stop the system keeping track of this URB
164 void usb_unanchor_urb(struct urb *urb)
167 struct usb_anchor *anchor;
172 anchor = urb->anchor;
176 spin_lock_irqsave(&anchor->lock, flags);
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.
182 if (likely(anchor == urb->anchor))
183 __usb_unanchor_urb(urb, anchor);
184 spin_unlock_irqrestore(&anchor->lock, flags);
186 EXPORT_SYMBOL_GPL(usb_unanchor_urb);
188 /*-------------------------------------------------------------------*/
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.
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").
202 * URBs may be submitted in interrupt context.
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.
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
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.
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
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.
251 * 0 on successful submissions. A negative error number otherwise.
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.
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).
269 * Reserved Bandwidth Transfers:
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.
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
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.
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
298 * GFP_NOFS is not ever used, as it has not been implemented yet.
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
305 * (c) current->state != TASK_RUNNING, this is the case only after
308 * GFP_NOIO is used in the block io path and error handling of storage
311 * All other situations use GFP_KERNEL.
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
327 int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
329 static int pipetypes[4] = {
330 PIPE_CONTROL, PIPE_ISOCHRONOUS, PIPE_BULK, PIPE_INTERRUPT
333 struct usb_device *dev;
334 struct usb_host_endpoint *ep;
336 unsigned int allowed;
338 if (!urb || !urb->complete)
341 WARN_ONCE(1, "URB %pK submitted while active\n", urb);
346 if ((!dev) || (dev->state < USB_STATE_UNAUTHENTICATED))
349 /* For now, get the endpoint from the pipe. Eventually drivers
350 * will be required to set urb->ep directly and we will eliminate
353 ep = usb_pipe_endpoint(dev, urb->pipe);
358 urb->status = -EINPROGRESS;
359 urb->actual_length = 0;
361 /* Lots of sanity checks, so HCDs can rely on clean data
362 * and don't need to duplicate tests
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;
371 is_out = !(setup->bRequestType & USB_DIR_IN) ||
374 is_out = usb_endpoint_dir_out(&ep->desc);
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);
384 if (xfertype != USB_ENDPOINT_XFER_CONTROL &&
385 dev->state < USB_STATE_CONFIGURED)
388 max = usb_endpoint_maxp(&ep->desc);
391 "bogus endpoint ep%d%s in %s (bad maxpacket %d)\n",
392 usb_endpoint_num(&ep->desc), is_out ? "out" : "in",
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.
401 if (xfertype == USB_ENDPOINT_XFER_ISOC) {
404 /* SuperSpeed isoc endpoints have up to 16 bursts of up to
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);
414 /* "high bandwidth" mode, 1-3 packets/uframe? */
415 if (dev->speed == USB_SPEED_HIGH)
416 max *= usb_endpoint_maxp_mult(&ep->desc);
418 if (urb->number_of_packets <= 0)
420 for (n = 0; n < urb->number_of_packets; n++) {
421 len = urb->iso_frame_desc[n].length;
422 if (len < 0 || len > max)
424 urb->iso_frame_desc[n].status = -EXDEV;
425 urb->iso_frame_desc[n].actual_length = 0;
427 } else if (urb->num_sgs && !urb->dev->bus->no_sg_constraint &&
428 dev->speed != USB_SPEED_WIRELESS) {
429 struct scatterlist *sg;
432 for_each_sg(urb->sg, sg, urb->num_sgs - 1, i)
433 if (sg->length % max)
437 /* the I/O buffer must be mapped/unmapped, except when length=0 */
438 if (urb->transfer_buffer_length > INT_MAX)
442 * stuff that drivers shouldn't do, but which shouldn't
443 * cause problems in HCDs if they get it wrong.
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]);
451 /* Check against a simple/standard policy */
452 allowed = (URB_NO_TRANSFER_DMA_MAP | URB_NO_INTERRUPT | URB_DIR_MASK |
455 case USB_ENDPOINT_XFER_BULK:
456 case USB_ENDPOINT_XFER_INT:
458 allowed |= URB_ZERO_PACKET;
460 case USB_ENDPOINT_XFER_CONTROL:
461 allowed |= URB_NO_FSBR; /* only affects UHCI */
463 default: /* all non-iso endpoints */
465 allowed |= URB_SHORT_NOT_OK;
467 case USB_ENDPOINT_XFER_ISOC:
468 allowed |= URB_ISO_ASAP;
471 allowed &= urb->transfer_flags;
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);
479 * Force periodic transfer intervals to be legal values that are
480 * a power of two (so HCDs don't need to).
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).
487 case USB_ENDPOINT_XFER_ISOC:
488 case USB_ENDPOINT_XFER_INT:
490 switch (dev->speed) {
491 case USB_SPEED_WIRELESS:
492 if ((urb->interval < 6)
493 && (xfertype == USB_ENDPOINT_XFER_INT))
497 if (urb->interval <= 0)
502 switch (dev->speed) {
503 case USB_SPEED_SUPER_PLUS:
504 case USB_SPEED_SUPER: /* units are 125us */
505 /* Handle up to 2^(16-1) microframes */
506 if (urb->interval > (1 << 15))
510 case USB_SPEED_WIRELESS:
511 if (urb->interval > 16)
514 case USB_SPEED_HIGH: /* units are microframes */
515 /* NOTE usb handles 2^15 */
516 if (urb->interval > (1024 * 8))
517 urb->interval = 1024 * 8;
520 case USB_SPEED_FULL: /* units are frames/msec */
522 if (xfertype == USB_ENDPOINT_XFER_INT) {
523 if (urb->interval > 255)
525 /* NOTE ohci only handles up to 32 */
528 if (urb->interval > 1024)
529 urb->interval = 1024;
530 /* NOTE usb and ohci handle up to 2^15 */
537 if (dev->speed != USB_SPEED_WIRELESS) {
538 /* Round down to a power of 2, no more than max */
539 urb->interval = min(max, 1 << ilog2(urb->interval));
543 return usb_hcd_submit_urb(urb, mem_flags);
545 EXPORT_SYMBOL_GPL(usb_submit_urb);
547 /*-------------------------------------------------------------------*/
550 * usb_unlink_urb - abort/cancel a transfer request for an endpoint
551 * @urb: pointer to urb describing a previously submitted request,
554 * This routine cancels an in-progress request. URBs complete only once
555 * per submission, and may be canceled only once per submission.
556 * Successful cancellation means termination of @urb will be expedited
557 * and the completion handler will be called with a status code
558 * indicating that the request has been canceled (rather than any other
561 * Drivers should not call this routine or related routines, such as
562 * usb_kill_urb() or usb_unlink_anchored_urbs(), after their disconnect
563 * method has returned. The disconnect function should synchronize with
564 * a driver's I/O routines to insure that all URB-related activity has
565 * completed before it returns.
567 * This request is asynchronous, however the HCD might call the ->complete()
568 * callback during unlink. Therefore when drivers call usb_unlink_urb(), they
569 * must not hold any locks that may be taken by the completion function.
570 * Success is indicated by returning -EINPROGRESS, at which time the URB will
571 * probably not yet have been given back to the device driver. When it is
572 * eventually called, the completion function will see @urb->status ==
574 * Failure is indicated by usb_unlink_urb() returning any other value.
575 * Unlinking will fail when @urb is not currently "linked" (i.e., it was
576 * never submitted, or it was unlinked before, or the hardware is already
577 * finished with it), even if the completion handler has not yet run.
579 * The URB must not be deallocated while this routine is running. In
580 * particular, when a driver calls this routine, it must insure that the
581 * completion handler cannot deallocate the URB.
583 * Return: -EINPROGRESS on success. See description for other values on
586 * Unlinking and Endpoint Queues:
588 * [The behaviors and guarantees described below do not apply to virtual
589 * root hubs but only to endpoint queues for physical USB devices.]
591 * Host Controller Drivers (HCDs) place all the URBs for a particular
592 * endpoint in a queue. Normally the queue advances as the controller
593 * hardware processes each request. But when an URB terminates with an
594 * error its queue generally stops (see below), at least until that URB's
595 * completion routine returns. It is guaranteed that a stopped queue
596 * will not restart until all its unlinked URBs have been fully retired,
597 * with their completion routines run, even if that's not until some time
598 * after the original completion handler returns. The same behavior and
599 * guarantee apply when an URB terminates because it was unlinked.
601 * Bulk and interrupt endpoint queues are guaranteed to stop whenever an
602 * URB terminates with any sort of error, including -ECONNRESET, -ENOENT,
603 * and -EREMOTEIO. Control endpoint queues behave the same way except
604 * that they are not guaranteed to stop for -EREMOTEIO errors. Queues
605 * for isochronous endpoints are treated differently, because they must
606 * advance at fixed rates. Such queues do not stop when an URB
607 * encounters an error or is unlinked. An unlinked isochronous URB may
608 * leave a gap in the stream of packets; it is undefined whether such
609 * gaps can be filled in.
611 * Note that early termination of an URB because a short packet was
612 * received will generate a -EREMOTEIO error if and only if the
613 * URB_SHORT_NOT_OK flag is set. By setting this flag, USB device
614 * drivers can build deep queues for large or complex bulk transfers
615 * and clean them up reliably after any sort of aborted transfer by
616 * unlinking all pending URBs at the first fault.
618 * When a control URB terminates with an error other than -EREMOTEIO, it
619 * is quite likely that the status stage of the transfer will not take
622 int usb_unlink_urb(struct urb *urb)
630 return usb_hcd_unlink_urb(urb, -ECONNRESET);
632 EXPORT_SYMBOL_GPL(usb_unlink_urb);
635 * usb_kill_urb - cancel a transfer request and wait for it to finish
636 * @urb: pointer to URB describing a previously submitted request,
639 * This routine cancels an in-progress request. It is guaranteed that
640 * upon return all completion handlers will have finished and the URB
641 * will be totally idle and available for reuse. These features make
642 * this an ideal way to stop I/O in a disconnect() callback or close()
643 * function. If the request has not already finished or been unlinked
644 * the completion handler will see urb->status == -ENOENT.
646 * While the routine is running, attempts to resubmit the URB will fail
647 * with error -EPERM. Thus even if the URB's completion handler always
648 * tries to resubmit, it will not succeed and the URB will become idle.
650 * The URB must not be deallocated while this routine is running. In
651 * particular, when a driver calls this routine, it must insure that the
652 * completion handler cannot deallocate the URB.
654 * This routine may not be used in an interrupt context (such as a bottom
655 * half or a completion handler), or when holding a spinlock, or in other
656 * situations where the caller can't schedule().
658 * This routine should not be called by a driver after its disconnect
659 * method has returned.
661 void usb_kill_urb(struct urb *urb)
664 if (!(urb && urb->dev && urb->ep))
666 atomic_inc(&urb->reject);
668 usb_hcd_unlink_urb(urb, -ENOENT);
669 wait_event(usb_kill_urb_queue, atomic_read(&urb->use_count) == 0);
671 atomic_dec(&urb->reject);
673 EXPORT_SYMBOL_GPL(usb_kill_urb);
676 * usb_poison_urb - reliably kill a transfer and prevent further use of an URB
677 * @urb: pointer to URB describing a previously submitted request,
680 * This routine cancels an in-progress request. It is guaranteed that
681 * upon return all completion handlers will have finished and the URB
682 * will be totally idle and cannot be reused. These features make
683 * this an ideal way to stop I/O in a disconnect() callback.
684 * If the request has not already finished or been unlinked
685 * the completion handler will see urb->status == -ENOENT.
687 * After and while the routine runs, attempts to resubmit the URB will fail
688 * with error -EPERM. Thus even if the URB's completion handler always
689 * tries to resubmit, it will not succeed and the URB will become idle.
691 * The URB must not be deallocated while this routine is running. In
692 * particular, when a driver calls this routine, it must insure that the
693 * completion handler cannot deallocate the URB.
695 * This routine may not be used in an interrupt context (such as a bottom
696 * half or a completion handler), or when holding a spinlock, or in other
697 * situations where the caller can't schedule().
699 * This routine should not be called by a driver after its disconnect
700 * method has returned.
702 void usb_poison_urb(struct urb *urb)
707 atomic_inc(&urb->reject);
709 if (!urb->dev || !urb->ep)
712 usb_hcd_unlink_urb(urb, -ENOENT);
713 wait_event(usb_kill_urb_queue, atomic_read(&urb->use_count) == 0);
715 EXPORT_SYMBOL_GPL(usb_poison_urb);
717 void usb_unpoison_urb(struct urb *urb)
722 atomic_dec(&urb->reject);
724 EXPORT_SYMBOL_GPL(usb_unpoison_urb);
727 * usb_block_urb - reliably prevent further use of an URB
728 * @urb: pointer to URB to be blocked, may be NULL
730 * After the routine has run, attempts to resubmit the URB will fail
731 * with error -EPERM. Thus even if the URB's completion handler always
732 * tries to resubmit, it will not succeed and the URB will become idle.
734 * The URB must not be deallocated while this routine is running. In
735 * particular, when a driver calls this routine, it must insure that the
736 * completion handler cannot deallocate the URB.
738 void usb_block_urb(struct urb *urb)
743 atomic_inc(&urb->reject);
745 EXPORT_SYMBOL_GPL(usb_block_urb);
748 * usb_kill_anchored_urbs - cancel transfer requests en masse
749 * @anchor: anchor the requests are bound to
751 * this allows all outstanding URBs to be killed starting
752 * from the back of the queue
754 * This routine should not be called by a driver after its disconnect
755 * method has returned.
757 void usb_kill_anchored_urbs(struct usb_anchor *anchor)
761 spin_lock_irq(&anchor->lock);
762 while (!list_empty(&anchor->urb_list)) {
763 victim = list_entry(anchor->urb_list.prev, struct urb,
765 /* we must make sure the URB isn't freed before we kill it*/
767 spin_unlock_irq(&anchor->lock);
768 /* this will unanchor the URB */
769 usb_kill_urb(victim);
771 spin_lock_irq(&anchor->lock);
773 spin_unlock_irq(&anchor->lock);
775 EXPORT_SYMBOL_GPL(usb_kill_anchored_urbs);
779 * usb_poison_anchored_urbs - cease all traffic from an anchor
780 * @anchor: anchor the requests are bound to
782 * this allows all outstanding URBs to be poisoned starting
783 * from the back of the queue. Newly added URBs will also be
786 * This routine should not be called by a driver after its disconnect
787 * method has returned.
789 void usb_poison_anchored_urbs(struct usb_anchor *anchor)
793 spin_lock_irq(&anchor->lock);
794 anchor->poisoned = 1;
795 while (!list_empty(&anchor->urb_list)) {
796 victim = list_entry(anchor->urb_list.prev, struct urb,
798 /* we must make sure the URB isn't freed before we kill it*/
800 spin_unlock_irq(&anchor->lock);
801 /* this will unanchor the URB */
802 usb_poison_urb(victim);
804 spin_lock_irq(&anchor->lock);
806 spin_unlock_irq(&anchor->lock);
808 EXPORT_SYMBOL_GPL(usb_poison_anchored_urbs);
811 * usb_unpoison_anchored_urbs - let an anchor be used successfully again
812 * @anchor: anchor the requests are bound to
814 * Reverses the effect of usb_poison_anchored_urbs
815 * the anchor can be used normally after it returns
817 void usb_unpoison_anchored_urbs(struct usb_anchor *anchor)
822 spin_lock_irqsave(&anchor->lock, flags);
823 list_for_each_entry(lazarus, &anchor->urb_list, anchor_list) {
824 usb_unpoison_urb(lazarus);
826 anchor->poisoned = 0;
827 spin_unlock_irqrestore(&anchor->lock, flags);
829 EXPORT_SYMBOL_GPL(usb_unpoison_anchored_urbs);
831 * usb_unlink_anchored_urbs - asynchronously cancel transfer requests en masse
832 * @anchor: anchor the requests are bound to
834 * this allows all outstanding URBs to be unlinked starting
835 * from the back of the queue. This function is asynchronous.
836 * The unlinking is just triggered. It may happen after this
837 * function has returned.
839 * This routine should not be called by a driver after its disconnect
840 * method has returned.
842 void usb_unlink_anchored_urbs(struct usb_anchor *anchor)
846 while ((victim = usb_get_from_anchor(anchor)) != NULL) {
847 usb_unlink_urb(victim);
851 EXPORT_SYMBOL_GPL(usb_unlink_anchored_urbs);
854 * usb_anchor_suspend_wakeups
855 * @anchor: the anchor you want to suspend wakeups on
857 * Call this to stop the last urb being unanchored from waking up any
858 * usb_wait_anchor_empty_timeout waiters. This is used in the hcd urb give-
859 * back path to delay waking up until after the completion handler has run.
861 void usb_anchor_suspend_wakeups(struct usb_anchor *anchor)
864 atomic_inc(&anchor->suspend_wakeups);
866 EXPORT_SYMBOL_GPL(usb_anchor_suspend_wakeups);
869 * usb_anchor_resume_wakeups
870 * @anchor: the anchor you want to resume wakeups on
872 * Allow usb_wait_anchor_empty_timeout waiters to be woken up again, and
873 * wake up any current waiters if the anchor is empty.
875 void usb_anchor_resume_wakeups(struct usb_anchor *anchor)
880 atomic_dec(&anchor->suspend_wakeups);
881 if (usb_anchor_check_wakeup(anchor))
882 wake_up(&anchor->wait);
884 EXPORT_SYMBOL_GPL(usb_anchor_resume_wakeups);
887 * usb_wait_anchor_empty_timeout - wait for an anchor to be unused
888 * @anchor: the anchor you want to become unused
889 * @timeout: how long you are willing to wait in milliseconds
891 * Call this is you want to be sure all an anchor's
894 * Return: Non-zero if the anchor became unused. Zero on timeout.
896 int usb_wait_anchor_empty_timeout(struct usb_anchor *anchor,
897 unsigned int timeout)
899 return wait_event_timeout(anchor->wait,
900 usb_anchor_check_wakeup(anchor),
901 msecs_to_jiffies(timeout));
903 EXPORT_SYMBOL_GPL(usb_wait_anchor_empty_timeout);
906 * usb_get_from_anchor - get an anchor's oldest urb
907 * @anchor: the anchor whose urb you want
909 * This will take the oldest urb from an anchor,
910 * unanchor and return it
912 * Return: The oldest urb from @anchor, or %NULL if @anchor has no
913 * urbs associated with it.
915 struct urb *usb_get_from_anchor(struct usb_anchor *anchor)
920 spin_lock_irqsave(&anchor->lock, flags);
921 if (!list_empty(&anchor->urb_list)) {
922 victim = list_entry(anchor->urb_list.next, struct urb,
925 __usb_unanchor_urb(victim, anchor);
929 spin_unlock_irqrestore(&anchor->lock, flags);
934 EXPORT_SYMBOL_GPL(usb_get_from_anchor);
937 * usb_scuttle_anchored_urbs - unanchor all an anchor's urbs
938 * @anchor: the anchor whose urbs you want to unanchor
940 * use this to get rid of all an anchor's urbs
942 void usb_scuttle_anchored_urbs(struct usb_anchor *anchor)
947 spin_lock_irqsave(&anchor->lock, flags);
948 while (!list_empty(&anchor->urb_list)) {
949 victim = list_entry(anchor->urb_list.prev, struct urb,
951 __usb_unanchor_urb(victim, anchor);
953 spin_unlock_irqrestore(&anchor->lock, flags);
956 EXPORT_SYMBOL_GPL(usb_scuttle_anchored_urbs);
959 * usb_anchor_empty - is an anchor empty
960 * @anchor: the anchor you want to query
962 * Return: 1 if the anchor has no urbs associated with it.
964 int usb_anchor_empty(struct usb_anchor *anchor)
966 return list_empty(&anchor->urb_list);
969 EXPORT_SYMBOL_GPL(usb_anchor_empty);