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->urb_list);
49 INIT_LIST_HEAD(&urb->anchor_list);
52 EXPORT_SYMBOL_GPL(usb_init_urb);
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.
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.
63 * If the driver want to use this urb for interrupt, control, or bulk
64 * endpoints, pass '0' as the number of iso packets.
66 * The driver must call usb_free_urb() when it is finished with the urb.
68 * Return: A pointer to the new urb, or %NULL if no memory is available.
70 struct urb *usb_alloc_urb(int iso_packets, gfp_t mem_flags)
74 urb = kmalloc(sizeof(struct urb) +
75 iso_packets * sizeof(struct usb_iso_packet_descriptor),
82 EXPORT_SYMBOL_GPL(usb_alloc_urb);
85 * usb_free_urb - frees the memory used by a urb when all users of it are finished
86 * @urb: pointer to the urb to free, may be NULL
88 * Must be called when a user of a urb is finished with it. When the last user
89 * of the urb calls this function, the memory of the urb is freed.
91 * Note: The transfer buffer associated with the urb is not freed unless the
92 * URB_FREE_BUFFER transfer flag is set.
94 void usb_free_urb(struct urb *urb)
97 kref_put(&urb->kref, urb_destroy);
99 EXPORT_SYMBOL_GPL(usb_free_urb);
102 * usb_get_urb - increments the reference count of the urb
103 * @urb: pointer to the urb to modify, may be NULL
105 * This must be called whenever a urb is transferred from a device driver to a
106 * host controller driver. This allows proper reference counting to happen
109 * Return: A pointer to the urb with the incremented reference counter.
111 struct urb *usb_get_urb(struct urb *urb)
114 kref_get(&urb->kref);
117 EXPORT_SYMBOL_GPL(usb_get_urb);
120 * usb_anchor_urb - anchors an URB while it is processed
121 * @urb: pointer to the urb to anchor
122 * @anchor: pointer to the anchor
124 * This can be called to have access to URBs which are to be executed
125 * without bothering to track them
127 void usb_anchor_urb(struct urb *urb, struct usb_anchor *anchor)
131 spin_lock_irqsave(&anchor->lock, flags);
133 list_add_tail(&urb->anchor_list, &anchor->urb_list);
134 urb->anchor = anchor;
136 if (unlikely(anchor->poisoned))
137 atomic_inc(&urb->reject);
139 spin_unlock_irqrestore(&anchor->lock, flags);
141 EXPORT_SYMBOL_GPL(usb_anchor_urb);
143 static int usb_anchor_check_wakeup(struct usb_anchor *anchor)
145 return atomic_read(&anchor->suspend_wakeups) == 0 &&
146 list_empty(&anchor->urb_list);
149 /* Callers must hold anchor->lock */
150 static void __usb_unanchor_urb(struct urb *urb, struct usb_anchor *anchor)
153 list_del(&urb->anchor_list);
155 if (usb_anchor_check_wakeup(anchor))
156 wake_up(&anchor->wait);
160 * usb_unanchor_urb - unanchors an URB
161 * @urb: pointer to the urb to anchor
163 * Call this to stop the system keeping track of this URB
165 void usb_unanchor_urb(struct urb *urb)
168 struct usb_anchor *anchor;
173 anchor = urb->anchor;
177 spin_lock_irqsave(&anchor->lock, flags);
179 * At this point, we could be competing with another thread which
180 * has the same intention. To protect the urb from being unanchored
181 * twice, only the winner of the race gets the job.
183 if (likely(anchor == urb->anchor))
184 __usb_unanchor_urb(urb, anchor);
185 spin_unlock_irqrestore(&anchor->lock, flags);
187 EXPORT_SYMBOL_GPL(usb_unanchor_urb);
189 /*-------------------------------------------------------------------*/
191 static const int pipetypes[4] = {
192 PIPE_CONTROL, PIPE_ISOCHRONOUS, PIPE_BULK, PIPE_INTERRUPT
196 * usb_urb_ep_type_check - sanity check of endpoint in the given urb
197 * @urb: urb to be checked
199 * This performs a light-weight sanity check for the endpoint in the
200 * given urb. It returns 0 if the urb contains a valid endpoint, otherwise
201 * a negative error code.
203 int usb_urb_ep_type_check(const struct urb *urb)
205 const struct usb_host_endpoint *ep;
207 ep = usb_pipe_endpoint(urb->dev, urb->pipe);
210 if (usb_pipetype(urb->pipe) != pipetypes[usb_endpoint_type(&ep->desc)])
214 EXPORT_SYMBOL_GPL(usb_urb_ep_type_check);
217 * usb_submit_urb - issue an asynchronous transfer request for an endpoint
218 * @urb: pointer to the urb describing the request
219 * @mem_flags: the type of memory to allocate, see kmalloc() for a list
220 * of valid options for this.
222 * This submits a transfer request, and transfers control of the URB
223 * describing that request to the USB subsystem. Request completion will
224 * be indicated later, asynchronously, by calling the completion handler.
225 * The three types of completion are success, error, and unlink
226 * (a software-induced fault, also called "request cancellation").
228 * URBs may be submitted in interrupt context.
230 * The caller must have correctly initialized the URB before submitting
231 * it. Functions such as usb_fill_bulk_urb() and usb_fill_control_urb() are
232 * available to ensure that most fields are correctly initialized, for
233 * the particular kind of transfer, although they will not initialize
234 * any transfer flags.
236 * If the submission is successful, the complete() callback from the URB
237 * will be called exactly once, when the USB core and Host Controller Driver
238 * (HCD) are finished with the URB. When the completion function is called,
239 * control of the URB is returned to the device driver which issued the
240 * request. The completion handler may then immediately free or reuse that
243 * With few exceptions, USB device drivers should never access URB fields
244 * provided by usbcore or the HCD until its complete() is called.
245 * The exceptions relate to periodic transfer scheduling. For both
246 * interrupt and isochronous urbs, as part of successful URB submission
247 * urb->interval is modified to reflect the actual transfer period used
248 * (normally some power of two units). And for isochronous urbs,
249 * urb->start_frame is modified to reflect when the URB's transfers were
250 * scheduled to start.
252 * Not all isochronous transfer scheduling policies will work, but most
253 * host controller drivers should easily handle ISO queues going from now
254 * until 10-200 msec into the future. Drivers should try to keep at
255 * least one or two msec of data in the queue; many controllers require
256 * that new transfers start at least 1 msec in the future when they are
257 * added. If the driver is unable to keep up and the queue empties out,
258 * the behavior for new submissions is governed by the URB_ISO_ASAP flag.
259 * If the flag is set, or if the queue is idle, then the URB is always
260 * assigned to the first available (and not yet expired) slot in the
261 * endpoint's schedule. If the flag is not set and the queue is active
262 * then the URB is always assigned to the next slot in the schedule
263 * following the end of the endpoint's previous URB, even if that slot is
264 * in the past. When a packet is assigned in this way to a slot that has
265 * already expired, the packet is not transmitted and the corresponding
266 * usb_iso_packet_descriptor's status field will return -EXDEV. If this
267 * would happen to all the packets in the URB, submission fails with a
270 * For control endpoints, the synchronous usb_control_msg() call is
271 * often used (in non-interrupt context) instead of this call.
272 * That is often used through convenience wrappers, for the requests
273 * that are standardized in the USB 2.0 specification. For bulk
274 * endpoints, a synchronous usb_bulk_msg() call is available.
277 * 0 on successful submissions. A negative error number otherwise.
281 * URBs may be submitted to endpoints before previous ones complete, to
282 * minimize the impact of interrupt latencies and system overhead on data
283 * throughput. With that queuing policy, an endpoint's queue would never
284 * be empty. This is required for continuous isochronous data streams,
285 * and may also be required for some kinds of interrupt transfers. Such
286 * queuing also maximizes bandwidth utilization by letting USB controllers
287 * start work on later requests before driver software has finished the
288 * completion processing for earlier (successful) requests.
290 * As of Linux 2.6, all USB endpoint transfer queues support depths greater
291 * than one. This was previously a HCD-specific behavior, except for ISO
292 * transfers. Non-isochronous endpoint queues are inactive during cleanup
293 * after faults (transfer errors or cancellation).
295 * Reserved Bandwidth Transfers:
297 * Periodic transfers (interrupt or isochronous) are performed repeatedly,
298 * using the interval specified in the urb. Submitting the first urb to
299 * the endpoint reserves the bandwidth necessary to make those transfers.
300 * If the USB subsystem can't allocate sufficient bandwidth to perform
301 * the periodic request, submitting such a periodic request should fail.
303 * For devices under xHCI, the bandwidth is reserved at configuration time, or
304 * when the alt setting is selected. If there is not enough bus bandwidth, the
305 * configuration/alt setting request will fail. Therefore, submissions to
306 * periodic endpoints on devices under xHCI should never fail due to bandwidth
309 * Device drivers must explicitly request that repetition, by ensuring that
310 * some URB is always on the endpoint's queue (except possibly for short
311 * periods during completion callbacks). When there is no longer an urb
312 * queued, the endpoint's bandwidth reservation is canceled. This means
313 * drivers can use their completion handlers to ensure they keep bandwidth
314 * they need, by reinitializing and resubmitting the just-completed urb
315 * until the driver longer needs that periodic bandwidth.
319 * The general rules for how to decide which mem_flags to use
320 * are the same as for kmalloc. There are four
321 * different possible values; GFP_KERNEL, GFP_NOFS, GFP_NOIO and
324 * GFP_NOFS is not ever used, as it has not been implemented yet.
326 * GFP_ATOMIC is used when
327 * (a) you are inside a completion handler, an interrupt, bottom half,
328 * tasklet or timer, or
329 * (b) you are holding a spinlock or rwlock (does not apply to
331 * (c) current->state != TASK_RUNNING, this is the case only after
334 * GFP_NOIO is used in the block io path and error handling of storage
337 * All other situations use GFP_KERNEL.
339 * Some more specific rules for mem_flags can be inferred, such as
340 * (1) start_xmit, timeout, and receive methods of network drivers must
341 * use GFP_ATOMIC (they are called with a spinlock held);
342 * (2) queuecommand methods of scsi drivers must use GFP_ATOMIC (also
343 * called with a spinlock held);
344 * (3) If you use a kernel thread with a network driver you must use
345 * GFP_NOIO, unless (b) or (c) apply;
346 * (4) after you have done a down() you can use GFP_KERNEL, unless (b) or (c)
347 * apply or your are in a storage driver's block io path;
348 * (5) USB probe and disconnect can use GFP_KERNEL unless (b) or (c) apply; and
349 * (6) changing firmware on a running storage or net device uses
350 * GFP_NOIO, unless b) or c) apply
353 int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
356 struct usb_device *dev;
357 struct usb_host_endpoint *ep;
359 unsigned int allowed;
361 if (!urb || !urb->complete)
364 WARN_ONCE(1, "URB %pK submitted while active\n", urb);
369 if ((!dev) || (dev->state < USB_STATE_UNAUTHENTICATED))
372 /* For now, get the endpoint from the pipe. Eventually drivers
373 * will be required to set urb->ep directly and we will eliminate
376 ep = usb_pipe_endpoint(dev, urb->pipe);
381 urb->status = -EINPROGRESS;
382 urb->actual_length = 0;
384 /* Lots of sanity checks, so HCDs can rely on clean data
385 * and don't need to duplicate tests
387 xfertype = usb_endpoint_type(&ep->desc);
388 if (xfertype == USB_ENDPOINT_XFER_CONTROL) {
389 struct usb_ctrlrequest *setup =
390 (struct usb_ctrlrequest *) urb->setup_packet;
394 is_out = !(setup->bRequestType & USB_DIR_IN) ||
397 is_out = usb_endpoint_dir_out(&ep->desc);
400 /* Clear the internal flags and cache the direction for later use */
401 urb->transfer_flags &= ~(URB_DIR_MASK | URB_DMA_MAP_SINGLE |
402 URB_DMA_MAP_PAGE | URB_DMA_MAP_SG | URB_MAP_LOCAL |
403 URB_SETUP_MAP_SINGLE | URB_SETUP_MAP_LOCAL |
404 URB_DMA_SG_COMBINED);
405 urb->transfer_flags |= (is_out ? URB_DIR_OUT : URB_DIR_IN);
407 if (xfertype != USB_ENDPOINT_XFER_CONTROL &&
408 dev->state < USB_STATE_CONFIGURED)
411 max = usb_endpoint_maxp(&ep->desc);
414 "bogus endpoint ep%d%s in %s (bad maxpacket %d)\n",
415 usb_endpoint_num(&ep->desc), is_out ? "out" : "in",
420 /* periodic transfers limit size per frame/uframe,
421 * but drivers only control those sizes for ISO.
422 * while we're checking, initialize return status.
424 if (xfertype == USB_ENDPOINT_XFER_ISOC) {
427 /* SuperSpeed isoc endpoints have up to 16 bursts of up to
430 if (dev->speed >= USB_SPEED_SUPER) {
431 int burst = 1 + ep->ss_ep_comp.bMaxBurst;
432 int mult = USB_SS_MULT(ep->ss_ep_comp.bmAttributes);
437 if (dev->speed == USB_SPEED_SUPER_PLUS &&
438 USB_SS_SSP_ISOC_COMP(ep->ss_ep_comp.bmAttributes)) {
439 struct usb_ssp_isoc_ep_comp_descriptor *isoc_ep_comp;
441 isoc_ep_comp = &ep->ssp_isoc_ep_comp;
442 max = le32_to_cpu(isoc_ep_comp->dwBytesPerInterval);
445 /* "high bandwidth" mode, 1-3 packets/uframe? */
446 if (dev->speed == USB_SPEED_HIGH)
447 max *= usb_endpoint_maxp_mult(&ep->desc);
449 if (urb->number_of_packets <= 0)
451 for (n = 0; n < urb->number_of_packets; n++) {
452 len = urb->iso_frame_desc[n].length;
453 if (len < 0 || len > max)
455 urb->iso_frame_desc[n].status = -EXDEV;
456 urb->iso_frame_desc[n].actual_length = 0;
458 } else if (urb->num_sgs && !urb->dev->bus->no_sg_constraint &&
459 dev->speed != USB_SPEED_WIRELESS) {
460 struct scatterlist *sg;
463 for_each_sg(urb->sg, sg, urb->num_sgs - 1, i)
464 if (sg->length % max)
468 /* the I/O buffer must be mapped/unmapped, except when length=0 */
469 if (urb->transfer_buffer_length > INT_MAX)
473 * stuff that drivers shouldn't do, but which shouldn't
474 * cause problems in HCDs if they get it wrong.
477 /* Check that the pipe's type matches the endpoint's type */
478 if (usb_urb_ep_type_check(urb))
479 dev_WARN(&dev->dev, "BOGUS urb xfer, pipe %x != type %x\n",
480 usb_pipetype(urb->pipe), pipetypes[xfertype]);
482 /* Check against a simple/standard policy */
483 allowed = (URB_NO_TRANSFER_DMA_MAP | URB_NO_INTERRUPT | URB_DIR_MASK |
486 case USB_ENDPOINT_XFER_BULK:
487 case USB_ENDPOINT_XFER_INT:
489 allowed |= URB_ZERO_PACKET;
491 default: /* all non-iso endpoints */
493 allowed |= URB_SHORT_NOT_OK;
495 case USB_ENDPOINT_XFER_ISOC:
496 allowed |= URB_ISO_ASAP;
499 allowed &= urb->transfer_flags;
501 /* warn if submitter gave bogus flags */
502 if (allowed != urb->transfer_flags)
503 dev_WARN(&dev->dev, "BOGUS urb flags, %x --> %x\n",
504 urb->transfer_flags, allowed);
507 * Force periodic transfer intervals to be legal values that are
508 * a power of two (so HCDs don't need to).
510 * FIXME want bus->{intr,iso}_sched_horizon values here. Each HC
511 * supports different values... this uses EHCI/UHCI defaults (and
512 * EHCI can use smaller non-default values).
515 case USB_ENDPOINT_XFER_ISOC:
516 case USB_ENDPOINT_XFER_INT:
518 switch (dev->speed) {
519 case USB_SPEED_WIRELESS:
520 if ((urb->interval < 6)
521 && (xfertype == USB_ENDPOINT_XFER_INT))
525 if (urb->interval <= 0)
530 switch (dev->speed) {
531 case USB_SPEED_SUPER_PLUS:
532 case USB_SPEED_SUPER: /* units are 125us */
533 /* Handle up to 2^(16-1) microframes */
534 if (urb->interval > (1 << 15))
538 case USB_SPEED_WIRELESS:
539 if (urb->interval > 16)
542 case USB_SPEED_HIGH: /* units are microframes */
543 /* NOTE usb handles 2^15 */
544 if (urb->interval > (1024 * 8))
545 urb->interval = 1024 * 8;
548 case USB_SPEED_FULL: /* units are frames/msec */
550 if (xfertype == USB_ENDPOINT_XFER_INT) {
551 if (urb->interval > 255)
553 /* NOTE ohci only handles up to 32 */
556 if (urb->interval > 1024)
557 urb->interval = 1024;
558 /* NOTE usb and ohci handle up to 2^15 */
565 if (dev->speed != USB_SPEED_WIRELESS) {
566 /* Round down to a power of 2, no more than max */
567 urb->interval = min(max, 1 << ilog2(urb->interval));
571 return usb_hcd_submit_urb(urb, mem_flags);
573 EXPORT_SYMBOL_GPL(usb_submit_urb);
575 /*-------------------------------------------------------------------*/
578 * usb_unlink_urb - abort/cancel a transfer request for an endpoint
579 * @urb: pointer to urb describing a previously submitted request,
582 * This routine cancels an in-progress request. URBs complete only once
583 * per submission, and may be canceled only once per submission.
584 * Successful cancellation means termination of @urb will be expedited
585 * and the completion handler will be called with a status code
586 * indicating that the request has been canceled (rather than any other
589 * Drivers should not call this routine or related routines, such as
590 * usb_kill_urb() or usb_unlink_anchored_urbs(), after their disconnect
591 * method has returned. The disconnect function should synchronize with
592 * a driver's I/O routines to insure that all URB-related activity has
593 * completed before it returns.
595 * This request is asynchronous, however the HCD might call the ->complete()
596 * callback during unlink. Therefore when drivers call usb_unlink_urb(), they
597 * must not hold any locks that may be taken by the completion function.
598 * Success is indicated by returning -EINPROGRESS, at which time the URB will
599 * probably not yet have been given back to the device driver. When it is
600 * eventually called, the completion function will see @urb->status ==
602 * Failure is indicated by usb_unlink_urb() returning any other value.
603 * Unlinking will fail when @urb is not currently "linked" (i.e., it was
604 * never submitted, or it was unlinked before, or the hardware is already
605 * finished with it), even if the completion handler has not yet run.
607 * The URB must not be deallocated while this routine is running. In
608 * particular, when a driver calls this routine, it must insure that the
609 * completion handler cannot deallocate the URB.
611 * Return: -EINPROGRESS on success. See description for other values on
614 * Unlinking and Endpoint Queues:
616 * [The behaviors and guarantees described below do not apply to virtual
617 * root hubs but only to endpoint queues for physical USB devices.]
619 * Host Controller Drivers (HCDs) place all the URBs for a particular
620 * endpoint in a queue. Normally the queue advances as the controller
621 * hardware processes each request. But when an URB terminates with an
622 * error its queue generally stops (see below), at least until that URB's
623 * completion routine returns. It is guaranteed that a stopped queue
624 * will not restart until all its unlinked URBs have been fully retired,
625 * with their completion routines run, even if that's not until some time
626 * after the original completion handler returns. The same behavior and
627 * guarantee apply when an URB terminates because it was unlinked.
629 * Bulk and interrupt endpoint queues are guaranteed to stop whenever an
630 * URB terminates with any sort of error, including -ECONNRESET, -ENOENT,
631 * and -EREMOTEIO. Control endpoint queues behave the same way except
632 * that they are not guaranteed to stop for -EREMOTEIO errors. Queues
633 * for isochronous endpoints are treated differently, because they must
634 * advance at fixed rates. Such queues do not stop when an URB
635 * encounters an error or is unlinked. An unlinked isochronous URB may
636 * leave a gap in the stream of packets; it is undefined whether such
637 * gaps can be filled in.
639 * Note that early termination of an URB because a short packet was
640 * received will generate a -EREMOTEIO error if and only if the
641 * URB_SHORT_NOT_OK flag is set. By setting this flag, USB device
642 * drivers can build deep queues for large or complex bulk transfers
643 * and clean them up reliably after any sort of aborted transfer by
644 * unlinking all pending URBs at the first fault.
646 * When a control URB terminates with an error other than -EREMOTEIO, it
647 * is quite likely that the status stage of the transfer will not take
650 int usb_unlink_urb(struct urb *urb)
658 return usb_hcd_unlink_urb(urb, -ECONNRESET);
660 EXPORT_SYMBOL_GPL(usb_unlink_urb);
663 * usb_kill_urb - cancel a transfer request and wait for it to finish
664 * @urb: pointer to URB describing a previously submitted request,
667 * This routine cancels an in-progress request. It is guaranteed that
668 * upon return all completion handlers will have finished and the URB
669 * will be totally idle and available for reuse. These features make
670 * this an ideal way to stop I/O in a disconnect() callback or close()
671 * function. If the request has not already finished or been unlinked
672 * the completion handler will see urb->status == -ENOENT.
674 * While the routine is running, attempts to resubmit the URB will fail
675 * with error -EPERM. Thus even if the URB's completion handler always
676 * tries to resubmit, it will not succeed and the URB will become idle.
678 * The URB must not be deallocated while this routine is running. In
679 * particular, when a driver calls this routine, it must insure that the
680 * completion handler cannot deallocate the URB.
682 * This routine may not be used in an interrupt context (such as a bottom
683 * half or a completion handler), or when holding a spinlock, or in other
684 * situations where the caller can't schedule().
686 * This routine should not be called by a driver after its disconnect
687 * method has returned.
689 void usb_kill_urb(struct urb *urb)
692 if (!(urb && urb->dev && urb->ep))
694 atomic_inc(&urb->reject);
696 * Order the write of urb->reject above before the read
697 * of urb->use_count below. Pairs with the barriers in
698 * __usb_hcd_giveback_urb() and usb_hcd_submit_urb().
700 smp_mb__after_atomic();
702 usb_hcd_unlink_urb(urb, -ENOENT);
703 wait_event(usb_kill_urb_queue, atomic_read(&urb->use_count) == 0);
705 atomic_dec(&urb->reject);
707 EXPORT_SYMBOL_GPL(usb_kill_urb);
710 * usb_poison_urb - reliably kill a transfer and prevent further use of an URB
711 * @urb: pointer to URB describing a previously submitted request,
714 * This routine cancels an in-progress request. It is guaranteed that
715 * upon return all completion handlers will have finished and the URB
716 * will be totally idle and cannot be reused. These features make
717 * this an ideal way to stop I/O in a disconnect() callback.
718 * If the request has not already finished or been unlinked
719 * the completion handler will see urb->status == -ENOENT.
721 * After and while the routine runs, attempts to resubmit the URB will fail
722 * with error -EPERM. Thus even if the URB's completion handler always
723 * tries to resubmit, it will not succeed and the URB will become idle.
725 * The URB must not be deallocated while this routine is running. In
726 * particular, when a driver calls this routine, it must insure that the
727 * completion handler cannot deallocate the URB.
729 * This routine may not be used in an interrupt context (such as a bottom
730 * half or a completion handler), or when holding a spinlock, or in other
731 * situations where the caller can't schedule().
733 * This routine should not be called by a driver after its disconnect
734 * method has returned.
736 void usb_poison_urb(struct urb *urb)
741 atomic_inc(&urb->reject);
743 * Order the write of urb->reject above before the read
744 * of urb->use_count below. Pairs with the barriers in
745 * __usb_hcd_giveback_urb() and usb_hcd_submit_urb().
747 smp_mb__after_atomic();
749 if (!urb->dev || !urb->ep)
752 usb_hcd_unlink_urb(urb, -ENOENT);
753 wait_event(usb_kill_urb_queue, atomic_read(&urb->use_count) == 0);
755 EXPORT_SYMBOL_GPL(usb_poison_urb);
757 void usb_unpoison_urb(struct urb *urb)
762 atomic_dec(&urb->reject);
764 EXPORT_SYMBOL_GPL(usb_unpoison_urb);
767 * usb_block_urb - reliably prevent further use of an URB
768 * @urb: pointer to URB to be blocked, may be NULL
770 * After the routine has run, attempts to resubmit the URB will fail
771 * with error -EPERM. Thus even if the URB's completion handler always
772 * tries to resubmit, it will not succeed and the URB will become idle.
774 * The URB must not be deallocated while this routine is running. In
775 * particular, when a driver calls this routine, it must insure that the
776 * completion handler cannot deallocate the URB.
778 void usb_block_urb(struct urb *urb)
783 atomic_inc(&urb->reject);
785 EXPORT_SYMBOL_GPL(usb_block_urb);
788 * usb_kill_anchored_urbs - kill all URBs associated with an anchor
789 * @anchor: anchor the requests are bound to
791 * This kills all outstanding URBs starting from the back of the queue,
792 * with guarantee that no completer callbacks will take place from the
793 * anchor after this function returns.
795 * This routine should not be called by a driver after its disconnect
796 * method has returned.
798 void usb_kill_anchored_urbs(struct usb_anchor *anchor)
804 spin_lock_irq(&anchor->lock);
805 while (!list_empty(&anchor->urb_list)) {
806 victim = list_entry(anchor->urb_list.prev,
807 struct urb, anchor_list);
808 /* make sure the URB isn't freed before we kill it */
810 spin_unlock_irq(&anchor->lock);
811 /* this will unanchor the URB */
812 usb_kill_urb(victim);
814 spin_lock_irq(&anchor->lock);
816 surely_empty = usb_anchor_check_wakeup(anchor);
818 spin_unlock_irq(&anchor->lock);
820 } while (!surely_empty);
822 EXPORT_SYMBOL_GPL(usb_kill_anchored_urbs);
826 * usb_poison_anchored_urbs - cease all traffic from an anchor
827 * @anchor: anchor the requests are bound to
829 * this allows all outstanding URBs to be poisoned starting
830 * from the back of the queue. Newly added URBs will also be
833 * This routine should not be called by a driver after its disconnect
834 * method has returned.
836 void usb_poison_anchored_urbs(struct usb_anchor *anchor)
842 spin_lock_irq(&anchor->lock);
843 anchor->poisoned = 1;
844 while (!list_empty(&anchor->urb_list)) {
845 victim = list_entry(anchor->urb_list.prev,
846 struct urb, anchor_list);
847 /* make sure the URB isn't freed before we kill it */
849 spin_unlock_irq(&anchor->lock);
850 /* this will unanchor the URB */
851 usb_poison_urb(victim);
853 spin_lock_irq(&anchor->lock);
855 surely_empty = usb_anchor_check_wakeup(anchor);
857 spin_unlock_irq(&anchor->lock);
859 } while (!surely_empty);
861 EXPORT_SYMBOL_GPL(usb_poison_anchored_urbs);
864 * usb_unpoison_anchored_urbs - let an anchor be used successfully again
865 * @anchor: anchor the requests are bound to
867 * Reverses the effect of usb_poison_anchored_urbs
868 * the anchor can be used normally after it returns
870 void usb_unpoison_anchored_urbs(struct usb_anchor *anchor)
875 spin_lock_irqsave(&anchor->lock, flags);
876 list_for_each_entry(lazarus, &anchor->urb_list, anchor_list) {
877 usb_unpoison_urb(lazarus);
879 anchor->poisoned = 0;
880 spin_unlock_irqrestore(&anchor->lock, flags);
882 EXPORT_SYMBOL_GPL(usb_unpoison_anchored_urbs);
884 * usb_unlink_anchored_urbs - asynchronously cancel transfer requests en masse
885 * @anchor: anchor the requests are bound to
887 * this allows all outstanding URBs to be unlinked starting
888 * from the back of the queue. This function is asynchronous.
889 * The unlinking is just triggered. It may happen after this
890 * function has returned.
892 * This routine should not be called by a driver after its disconnect
893 * method has returned.
895 void usb_unlink_anchored_urbs(struct usb_anchor *anchor)
899 while ((victim = usb_get_from_anchor(anchor)) != NULL) {
900 usb_unlink_urb(victim);
904 EXPORT_SYMBOL_GPL(usb_unlink_anchored_urbs);
907 * usb_anchor_suspend_wakeups
908 * @anchor: the anchor you want to suspend wakeups on
910 * Call this to stop the last urb being unanchored from waking up any
911 * usb_wait_anchor_empty_timeout waiters. This is used in the hcd urb give-
912 * back path to delay waking up until after the completion handler has run.
914 void usb_anchor_suspend_wakeups(struct usb_anchor *anchor)
917 atomic_inc(&anchor->suspend_wakeups);
919 EXPORT_SYMBOL_GPL(usb_anchor_suspend_wakeups);
922 * usb_anchor_resume_wakeups
923 * @anchor: the anchor you want to resume wakeups on
925 * Allow usb_wait_anchor_empty_timeout waiters to be woken up again, and
926 * wake up any current waiters if the anchor is empty.
928 void usb_anchor_resume_wakeups(struct usb_anchor *anchor)
933 atomic_dec(&anchor->suspend_wakeups);
934 if (usb_anchor_check_wakeup(anchor))
935 wake_up(&anchor->wait);
937 EXPORT_SYMBOL_GPL(usb_anchor_resume_wakeups);
940 * usb_wait_anchor_empty_timeout - wait for an anchor to be unused
941 * @anchor: the anchor you want to become unused
942 * @timeout: how long you are willing to wait in milliseconds
944 * Call this is you want to be sure all an anchor's
947 * Return: Non-zero if the anchor became unused. Zero on timeout.
949 int usb_wait_anchor_empty_timeout(struct usb_anchor *anchor,
950 unsigned int timeout)
952 return wait_event_timeout(anchor->wait,
953 usb_anchor_check_wakeup(anchor),
954 msecs_to_jiffies(timeout));
956 EXPORT_SYMBOL_GPL(usb_wait_anchor_empty_timeout);
959 * usb_get_from_anchor - get an anchor's oldest urb
960 * @anchor: the anchor whose urb you want
962 * This will take the oldest urb from an anchor,
963 * unanchor and return it
965 * Return: The oldest urb from @anchor, or %NULL if @anchor has no
966 * urbs associated with it.
968 struct urb *usb_get_from_anchor(struct usb_anchor *anchor)
973 spin_lock_irqsave(&anchor->lock, flags);
974 if (!list_empty(&anchor->urb_list)) {
975 victim = list_entry(anchor->urb_list.next, struct urb,
978 __usb_unanchor_urb(victim, anchor);
982 spin_unlock_irqrestore(&anchor->lock, flags);
987 EXPORT_SYMBOL_GPL(usb_get_from_anchor);
990 * usb_scuttle_anchored_urbs - unanchor all an anchor's urbs
991 * @anchor: the anchor whose urbs you want to unanchor
993 * use this to get rid of all an anchor's urbs
995 void usb_scuttle_anchored_urbs(struct usb_anchor *anchor)
1002 spin_lock_irqsave(&anchor->lock, flags);
1003 while (!list_empty(&anchor->urb_list)) {
1004 victim = list_entry(anchor->urb_list.prev,
1005 struct urb, anchor_list);
1006 __usb_unanchor_urb(victim, anchor);
1008 surely_empty = usb_anchor_check_wakeup(anchor);
1010 spin_unlock_irqrestore(&anchor->lock, flags);
1012 } while (!surely_empty);
1015 EXPORT_SYMBOL_GPL(usb_scuttle_anchored_urbs);
1018 * usb_anchor_empty - is an anchor empty
1019 * @anchor: the anchor you want to query
1021 * Return: 1 if the anchor has no urbs associated with it.
1023 int usb_anchor_empty(struct usb_anchor *anchor)
1025 return list_empty(&anchor->urb_list);
1028 EXPORT_SYMBOL_GPL(usb_anchor_empty);