1 #include <linux/module.h>
2 #include <linux/string.h>
3 #include <linux/bitops.h>
4 #include <linux/slab.h>
5 #include <linux/init.h>
6 #include <linux/log2.h>
7 #include <linux/usb.h>
8 #include <linux/wait.h>
9 #include <linux/usb/hcd.h>
10 
11 #define to_urb(d) container_of(d, struct urb, kref)
12 
13 
urb_destroy(struct kref * kref)14 static void urb_destroy(struct kref *kref)
15 {
16 	struct urb *urb = to_urb(kref);
17 
18 	if (urb->transfer_flags & URB_FREE_BUFFER)
19 		kfree(urb->transfer_buffer);
20 
21 	kfree(urb);
22 }
23 
24 /**
25  * usb_init_urb - initializes a urb so that it can be used by a USB driver
26  * @urb: pointer to the urb to initialize
27  *
28  * Initializes a urb so that the USB subsystem can use it properly.
29  *
30  * If a urb is created with a call to usb_alloc_urb() it is not
31  * necessary to call this function.  Only use this if you allocate the
32  * space for a struct urb on your own.  If you call this function, be
33  * careful when freeing the memory for your urb that it is no longer in
34  * use by the USB core.
35  *
36  * Only use this function if you _really_ understand what you are doing.
37  */
usb_init_urb(struct urb * urb)38 void usb_init_urb(struct urb *urb)
39 {
40 	if (urb) {
41 		memset(urb, 0, sizeof(*urb));
42 		kref_init(&urb->kref);
43 		INIT_LIST_HEAD(&urb->anchor_list);
44 	}
45 }
46 EXPORT_SYMBOL_GPL(usb_init_urb);
47 
48 /**
49  * usb_alloc_urb - creates a new urb for a USB driver to use
50  * @iso_packets: number of iso packets for this urb
51  * @mem_flags: the type of memory to allocate, see kmalloc() for a list of
52  *	valid options for this.
53  *
54  * Creates an urb for the USB driver to use, initializes a few internal
55  * structures, incrementes the usage counter, and returns a pointer to it.
56  *
57  * If no memory is available, NULL is returned.
58  *
59  * If the driver want to use this urb for interrupt, control, or bulk
60  * endpoints, pass '0' as the number of iso packets.
61  *
62  * The driver must call usb_free_urb() when it is finished with the urb.
63  */
usb_alloc_urb(int iso_packets,gfp_t mem_flags)64 struct urb *usb_alloc_urb(int iso_packets, gfp_t mem_flags)
65 {
66 	struct urb *urb;
67 
68 	urb = kmalloc(sizeof(struct urb) +
69 		iso_packets * sizeof(struct usb_iso_packet_descriptor),
70 		mem_flags);
71 	if (!urb) {
72 		printk(KERN_ERR "alloc_urb: kmalloc failed\n");
73 		return NULL;
74 	}
75 	usb_init_urb(urb);
76 	return urb;
77 }
78 EXPORT_SYMBOL_GPL(usb_alloc_urb);
79 
80 /**
81  * usb_free_urb - frees the memory used by a urb when all users of it are finished
82  * @urb: pointer to the urb to free, may be NULL
83  *
84  * Must be called when a user of a urb is finished with it.  When the last user
85  * of the urb calls this function, the memory of the urb is freed.
86  *
87  * Note: The transfer buffer associated with the urb is not freed unless the
88  * URB_FREE_BUFFER transfer flag is set.
89  */
usb_free_urb(struct urb * urb)90 void usb_free_urb(struct urb *urb)
91 {
92 	if (urb)
93 		kref_put(&urb->kref, urb_destroy);
94 }
95 EXPORT_SYMBOL_GPL(usb_free_urb);
96 
97 /**
98  * usb_get_urb - increments the reference count of the urb
99  * @urb: pointer to the urb to modify, may be NULL
100  *
101  * This must be  called whenever a urb is transferred from a device driver to a
102  * host controller driver.  This allows proper reference counting to happen
103  * for urbs.
104  *
105  * A pointer to the urb with the incremented reference counter is returned.
106  */
usb_get_urb(struct urb * urb)107 struct urb *usb_get_urb(struct urb *urb)
108 {
109 	if (urb)
110 		kref_get(&urb->kref);
111 	return urb;
112 }
113 EXPORT_SYMBOL_GPL(usb_get_urb);
114 
115 /**
116  * usb_anchor_urb - anchors an URB while it is processed
117  * @urb: pointer to the urb to anchor
118  * @anchor: pointer to the anchor
119  *
120  * This can be called to have access to URBs which are to be executed
121  * without bothering to track them
122  */
usb_anchor_urb(struct urb * urb,struct usb_anchor * anchor)123 void usb_anchor_urb(struct urb *urb, struct usb_anchor *anchor)
124 {
125 	unsigned long flags;
126 
127 	spin_lock_irqsave(&anchor->lock, flags);
128 	usb_get_urb(urb);
129 	list_add_tail(&urb->anchor_list, &anchor->urb_list);
130 	urb->anchor = anchor;
131 
132 	if (unlikely(anchor->poisoned)) {
133 		atomic_inc(&urb->reject);
134 	}
135 
136 	spin_unlock_irqrestore(&anchor->lock, flags);
137 }
138 EXPORT_SYMBOL_GPL(usb_anchor_urb);
139 
140 /* Callers must hold anchor->lock */
__usb_unanchor_urb(struct urb * urb,struct usb_anchor * anchor)141 static void __usb_unanchor_urb(struct urb *urb, struct usb_anchor *anchor)
142 {
143 	urb->anchor = NULL;
144 	list_del(&urb->anchor_list);
145 	usb_put_urb(urb);
146 	if (list_empty(&anchor->urb_list))
147 		wake_up(&anchor->wait);
148 }
149 
150 /**
151  * usb_unanchor_urb - unanchors an URB
152  * @urb: pointer to the urb to anchor
153  *
154  * Call this to stop the system keeping track of this URB
155  */
usb_unanchor_urb(struct urb * urb)156 void usb_unanchor_urb(struct urb *urb)
157 {
158 	unsigned long flags;
159 	struct usb_anchor *anchor;
160 
161 	if (!urb)
162 		return;
163 
164 	anchor = urb->anchor;
165 	if (!anchor)
166 		return;
167 
168 	spin_lock_irqsave(&anchor->lock, flags);
169 	/*
170 	 * At this point, we could be competing with another thread which
171 	 * has the same intention. To protect the urb from being unanchored
172 	 * twice, only the winner of the race gets the job.
173 	 */
174 	if (likely(anchor == urb->anchor))
175 		__usb_unanchor_urb(urb, anchor);
176 	spin_unlock_irqrestore(&anchor->lock, flags);
177 }
178 EXPORT_SYMBOL_GPL(usb_unanchor_urb);
179 
180 /*-------------------------------------------------------------------*/
181 
182 /**
183  * usb_submit_urb - issue an asynchronous transfer request for an endpoint
184  * @urb: pointer to the urb describing the request
185  * @mem_flags: the type of memory to allocate, see kmalloc() for a list
186  *	of valid options for this.
187  *
188  * This submits a transfer request, and transfers control of the URB
189  * describing that request to the USB subsystem.  Request completion will
190  * be indicated later, asynchronously, by calling the completion handler.
191  * The three types of completion are success, error, and unlink
192  * (a software-induced fault, also called "request cancellation").
193  *
194  * URBs may be submitted in interrupt context.
195  *
196  * The caller must have correctly initialized the URB before submitting
197  * it.  Functions such as usb_fill_bulk_urb() and usb_fill_control_urb() are
198  * available to ensure that most fields are correctly initialized, for
199  * the particular kind of transfer, although they will not initialize
200  * any transfer flags.
201  *
202  * Successful submissions return 0; otherwise this routine returns a
203  * negative error number.  If the submission is successful, the complete()
204  * callback from the URB will be called exactly once, when the USB core and
205  * Host Controller Driver (HCD) are finished with the URB.  When the completion
206  * function is called, control of the URB is returned to the device
207  * driver which issued the request.  The completion handler may then
208  * immediately free or reuse that URB.
209  *
210  * With few exceptions, USB device drivers should never access URB fields
211  * provided by usbcore or the HCD until its complete() is called.
212  * The exceptions relate to periodic transfer scheduling.  For both
213  * interrupt and isochronous urbs, as part of successful URB submission
214  * urb->interval is modified to reflect the actual transfer period used
215  * (normally some power of two units).  And for isochronous urbs,
216  * urb->start_frame is modified to reflect when the URB's transfers were
217  * scheduled to start.  Not all isochronous transfer scheduling policies
218  * will work, but most host controller drivers should easily handle ISO
219  * queues going from now until 10-200 msec into the future.
220  *
221  * For control endpoints, the synchronous usb_control_msg() call is
222  * often used (in non-interrupt context) instead of this call.
223  * That is often used through convenience wrappers, for the requests
224  * that are standardized in the USB 2.0 specification.  For bulk
225  * endpoints, a synchronous usb_bulk_msg() call is available.
226  *
227  * Request Queuing:
228  *
229  * URBs may be submitted to endpoints before previous ones complete, to
230  * minimize the impact of interrupt latencies and system overhead on data
231  * throughput.  With that queuing policy, an endpoint's queue would never
232  * be empty.  This is required for continuous isochronous data streams,
233  * and may also be required for some kinds of interrupt transfers. Such
234  * queuing also maximizes bandwidth utilization by letting USB controllers
235  * start work on later requests before driver software has finished the
236  * completion processing for earlier (successful) requests.
237  *
238  * As of Linux 2.6, all USB endpoint transfer queues support depths greater
239  * than one.  This was previously a HCD-specific behavior, except for ISO
240  * transfers.  Non-isochronous endpoint queues are inactive during cleanup
241  * after faults (transfer errors or cancellation).
242  *
243  * Reserved Bandwidth Transfers:
244  *
245  * Periodic transfers (interrupt or isochronous) are performed repeatedly,
246  * using the interval specified in the urb.  Submitting the first urb to
247  * the endpoint reserves the bandwidth necessary to make those transfers.
248  * If the USB subsystem can't allocate sufficient bandwidth to perform
249  * the periodic request, submitting such a periodic request should fail.
250  *
251  * For devices under xHCI, the bandwidth is reserved at configuration time, or
252  * when the alt setting is selected.  If there is not enough bus bandwidth, the
253  * configuration/alt setting request will fail.  Therefore, submissions to
254  * periodic endpoints on devices under xHCI should never fail due to bandwidth
255  * constraints.
256  *
257  * Device drivers must explicitly request that repetition, by ensuring that
258  * some URB is always on the endpoint's queue (except possibly for short
259  * periods during completion callacks).  When there is no longer an urb
260  * queued, the endpoint's bandwidth reservation is canceled.  This means
261  * drivers can use their completion handlers to ensure they keep bandwidth
262  * they need, by reinitializing and resubmitting the just-completed urb
263  * until the driver longer needs that periodic bandwidth.
264  *
265  * Memory Flags:
266  *
267  * The general rules for how to decide which mem_flags to use
268  * are the same as for kmalloc.  There are four
269  * different possible values; GFP_KERNEL, GFP_NOFS, GFP_NOIO and
270  * GFP_ATOMIC.
271  *
272  * GFP_NOFS is not ever used, as it has not been implemented yet.
273  *
274  * GFP_ATOMIC is used when
275  *   (a) you are inside a completion handler, an interrupt, bottom half,
276  *       tasklet or timer, or
277  *   (b) you are holding a spinlock or rwlock (does not apply to
278  *       semaphores), or
279  *   (c) current->state != TASK_RUNNING, this is the case only after
280  *       you've changed it.
281  *
282  * GFP_NOIO is used in the block io path and error handling of storage
283  * devices.
284  *
285  * All other situations use GFP_KERNEL.
286  *
287  * Some more specific rules for mem_flags can be inferred, such as
288  *  (1) start_xmit, timeout, and receive methods of network drivers must
289  *      use GFP_ATOMIC (they are called with a spinlock held);
290  *  (2) queuecommand methods of scsi drivers must use GFP_ATOMIC (also
291  *      called with a spinlock held);
292  *  (3) If you use a kernel thread with a network driver you must use
293  *      GFP_NOIO, unless (b) or (c) apply;
294  *  (4) after you have done a down() you can use GFP_KERNEL, unless (b) or (c)
295  *      apply or your are in a storage driver's block io path;
296  *  (5) USB probe and disconnect can use GFP_KERNEL unless (b) or (c) apply; and
297  *  (6) changing firmware on a running storage or net device uses
298  *      GFP_NOIO, unless b) or c) apply
299  *
300  */
usb_submit_urb(struct urb * urb,gfp_t mem_flags)301 int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
302 {
303 	int				xfertype, max;
304 	struct usb_device		*dev;
305 	struct usb_host_endpoint	*ep;
306 	int				is_out;
307 
308 	if (!urb || urb->hcpriv || !urb->complete)
309 		return -EINVAL;
310 	dev = urb->dev;
311 	if ((!dev) || (dev->state < USB_STATE_UNAUTHENTICATED))
312 		return -ENODEV;
313 
314 	/* For now, get the endpoint from the pipe.  Eventually drivers
315 	 * will be required to set urb->ep directly and we will eliminate
316 	 * urb->pipe.
317 	 */
318 	ep = usb_pipe_endpoint(dev, urb->pipe);
319 	if (!ep)
320 		return -ENOENT;
321 
322 	urb->ep = ep;
323 	urb->status = -EINPROGRESS;
324 	urb->actual_length = 0;
325 
326 	/* Lots of sanity checks, so HCDs can rely on clean data
327 	 * and don't need to duplicate tests
328 	 */
329 	xfertype = usb_endpoint_type(&ep->desc);
330 	if (xfertype == USB_ENDPOINT_XFER_CONTROL) {
331 		struct usb_ctrlrequest *setup =
332 				(struct usb_ctrlrequest *) urb->setup_packet;
333 
334 		if (!setup)
335 			return -ENOEXEC;
336 		is_out = !(setup->bRequestType & USB_DIR_IN) ||
337 				!setup->wLength;
338 	} else {
339 		is_out = usb_endpoint_dir_out(&ep->desc);
340 	}
341 
342 	/* Clear the internal flags and cache the direction for later use */
343 	urb->transfer_flags &= ~(URB_DIR_MASK | URB_DMA_MAP_SINGLE |
344 			URB_DMA_MAP_PAGE | URB_DMA_MAP_SG | URB_MAP_LOCAL |
345 			URB_SETUP_MAP_SINGLE | URB_SETUP_MAP_LOCAL |
346 			URB_DMA_SG_COMBINED);
347 	urb->transfer_flags |= (is_out ? URB_DIR_OUT : URB_DIR_IN);
348 
349 	if (xfertype != USB_ENDPOINT_XFER_CONTROL &&
350 			dev->state < USB_STATE_CONFIGURED)
351 		return -ENODEV;
352 
353 	max = usb_endpoint_maxp(&ep->desc);
354 	if (max <= 0) {
355 		dev_dbg(&dev->dev,
356 			"bogus endpoint ep%d%s in %s (bad maxpacket %d)\n",
357 			usb_endpoint_num(&ep->desc), is_out ? "out" : "in",
358 			__func__, max);
359 		return -EMSGSIZE;
360 	}
361 
362 	/* periodic transfers limit size per frame/uframe,
363 	 * but drivers only control those sizes for ISO.
364 	 * while we're checking, initialize return status.
365 	 */
366 	if (xfertype == USB_ENDPOINT_XFER_ISOC) {
367 		int	n, len;
368 
369 		/* SuperSpeed isoc endpoints have up to 16 bursts of up to
370 		 * 3 packets each
371 		 */
372 		if (dev->speed == USB_SPEED_SUPER) {
373 			int     burst = 1 + ep->ss_ep_comp.bMaxBurst;
374 			int     mult = USB_SS_MULT(ep->ss_ep_comp.bmAttributes);
375 			max *= burst;
376 			max *= mult;
377 		}
378 
379 		/* "high bandwidth" mode, 1-3 packets/uframe? */
380 		if (dev->speed == USB_SPEED_HIGH) {
381 			int	mult = 1 + ((max >> 11) & 0x03);
382 			max &= 0x07ff;
383 			max *= mult;
384 		}
385 
386 		if (urb->number_of_packets <= 0)
387 			return -EINVAL;
388 		for (n = 0; n < urb->number_of_packets; n++) {
389 			len = urb->iso_frame_desc[n].length;
390 			if (len < 0 || len > max)
391 				return -EMSGSIZE;
392 			urb->iso_frame_desc[n].status = -EXDEV;
393 			urb->iso_frame_desc[n].actual_length = 0;
394 		}
395 	}
396 
397 	/* the I/O buffer must be mapped/unmapped, except when length=0 */
398 	if (urb->transfer_buffer_length > INT_MAX)
399 		return -EMSGSIZE;
400 
401 #ifdef DEBUG
402 	/* stuff that drivers shouldn't do, but which shouldn't
403 	 * cause problems in HCDs if they get it wrong.
404 	 */
405 	{
406 	unsigned int	allowed;
407 	static int pipetypes[4] = {
408 		PIPE_CONTROL, PIPE_ISOCHRONOUS, PIPE_BULK, PIPE_INTERRUPT
409 	};
410 
411 	/* Check that the pipe's type matches the endpoint's type */
412 	if (usb_pipetype(urb->pipe) != pipetypes[xfertype])
413 		dev_WARN(&dev->dev, "BOGUS urb xfer, pipe %x != type %x\n",
414 			usb_pipetype(urb->pipe), pipetypes[xfertype]);
415 
416 	/* Check against a simple/standard policy */
417 	allowed = (URB_NO_TRANSFER_DMA_MAP | URB_NO_INTERRUPT | URB_DIR_MASK |
418 			URB_FREE_BUFFER);
419 	switch (xfertype) {
420 	case USB_ENDPOINT_XFER_BULK:
421 		if (is_out)
422 			allowed |= URB_ZERO_PACKET;
423 		/* FALLTHROUGH */
424 	case USB_ENDPOINT_XFER_CONTROL:
425 		allowed |= URB_NO_FSBR;	/* only affects UHCI */
426 		/* FALLTHROUGH */
427 	default:			/* all non-iso endpoints */
428 		if (!is_out)
429 			allowed |= URB_SHORT_NOT_OK;
430 		break;
431 	case USB_ENDPOINT_XFER_ISOC:
432 		allowed |= URB_ISO_ASAP;
433 		break;
434 	}
435 	allowed &= urb->transfer_flags;
436 
437 	/* warn if submitter gave bogus flags */
438 	if (allowed != urb->transfer_flags)
439 		dev_WARN(&dev->dev, "BOGUS urb flags, %x --> %x\n",
440 			urb->transfer_flags, allowed);
441 	}
442 #endif
443 	/*
444 	 * Force periodic transfer intervals to be legal values that are
445 	 * a power of two (so HCDs don't need to).
446 	 *
447 	 * FIXME want bus->{intr,iso}_sched_horizon values here.  Each HC
448 	 * supports different values... this uses EHCI/UHCI defaults (and
449 	 * EHCI can use smaller non-default values).
450 	 */
451 	switch (xfertype) {
452 	case USB_ENDPOINT_XFER_ISOC:
453 	case USB_ENDPOINT_XFER_INT:
454 		/* too small? */
455 		switch (dev->speed) {
456 		case USB_SPEED_WIRELESS:
457 			if (urb->interval < 6)
458 				return -EINVAL;
459 			break;
460 		default:
461 			if (urb->interval <= 0)
462 				return -EINVAL;
463 			break;
464 		}
465 		/* too big? */
466 		switch (dev->speed) {
467 		case USB_SPEED_SUPER:	/* units are 125us */
468 			/* Handle up to 2^(16-1) microframes */
469 			if (urb->interval > (1 << 15))
470 				return -EINVAL;
471 			max = 1 << 15;
472 			break;
473 		case USB_SPEED_WIRELESS:
474 			if (urb->interval > 16)
475 				return -EINVAL;
476 			break;
477 		case USB_SPEED_HIGH:	/* units are microframes */
478 			/* NOTE usb handles 2^15 */
479 			if (urb->interval > (1024 * 8))
480 				urb->interval = 1024 * 8;
481 			max = 1024 * 8;
482 			break;
483 		case USB_SPEED_FULL:	/* units are frames/msec */
484 		case USB_SPEED_LOW:
485 			if (xfertype == USB_ENDPOINT_XFER_INT) {
486 				if (urb->interval > 255)
487 					return -EINVAL;
488 				/* NOTE ohci only handles up to 32 */
489 				max = 128;
490 			} else {
491 				if (urb->interval > 1024)
492 					urb->interval = 1024;
493 				/* NOTE usb and ohci handle up to 2^15 */
494 				max = 1024;
495 			}
496 			break;
497 		default:
498 			return -EINVAL;
499 		}
500 		if (dev->speed != USB_SPEED_WIRELESS) {
501 			/* Round down to a power of 2, no more than max */
502 			urb->interval = min(max, 1 << ilog2(urb->interval));
503 		}
504 	}
505 
506 	return usb_hcd_submit_urb(urb, mem_flags);
507 }
508 EXPORT_SYMBOL_GPL(usb_submit_urb);
509 
510 /*-------------------------------------------------------------------*/
511 
512 /**
513  * usb_unlink_urb - abort/cancel a transfer request for an endpoint
514  * @urb: pointer to urb describing a previously submitted request,
515  *	may be NULL
516  *
517  * This routine cancels an in-progress request.  URBs complete only once
518  * per submission, and may be canceled only once per submission.
519  * Successful cancellation means termination of @urb will be expedited
520  * and the completion handler will be called with a status code
521  * indicating that the request has been canceled (rather than any other
522  * code).
523  *
524  * Drivers should not call this routine or related routines, such as
525  * usb_kill_urb() or usb_unlink_anchored_urbs(), after their disconnect
526  * method has returned.  The disconnect function should synchronize with
527  * a driver's I/O routines to insure that all URB-related activity has
528  * completed before it returns.
529  *
530  * This request is asynchronous, however the HCD might call the ->complete()
531  * callback during unlink. Therefore when drivers call usb_unlink_urb(), they
532  * must not hold any locks that may be taken by the completion function.
533  * Success is indicated by returning -EINPROGRESS, at which time the URB will
534  * probably not yet have been given back to the device driver. When it is
535  * eventually called, the completion function will see @urb->status ==
536  * -ECONNRESET.
537  * Failure is indicated by usb_unlink_urb() returning any other value.
538  * Unlinking will fail when @urb is not currently "linked" (i.e., it was
539  * never submitted, or it was unlinked before, or the hardware is already
540  * finished with it), even if the completion handler has not yet run.
541  *
542  * The URB must not be deallocated while this routine is running.  In
543  * particular, when a driver calls this routine, it must insure that the
544  * completion handler cannot deallocate the URB.
545  *
546  * Unlinking and Endpoint Queues:
547  *
548  * [The behaviors and guarantees described below do not apply to virtual
549  * root hubs but only to endpoint queues for physical USB devices.]
550  *
551  * Host Controller Drivers (HCDs) place all the URBs for a particular
552  * endpoint in a queue.  Normally the queue advances as the controller
553  * hardware processes each request.  But when an URB terminates with an
554  * error its queue generally stops (see below), at least until that URB's
555  * completion routine returns.  It is guaranteed that a stopped queue
556  * will not restart until all its unlinked URBs have been fully retired,
557  * with their completion routines run, even if that's not until some time
558  * after the original completion handler returns.  The same behavior and
559  * guarantee apply when an URB terminates because it was unlinked.
560  *
561  * Bulk and interrupt endpoint queues are guaranteed to stop whenever an
562  * URB terminates with any sort of error, including -ECONNRESET, -ENOENT,
563  * and -EREMOTEIO.  Control endpoint queues behave the same way except
564  * that they are not guaranteed to stop for -EREMOTEIO errors.  Queues
565  * for isochronous endpoints are treated differently, because they must
566  * advance at fixed rates.  Such queues do not stop when an URB
567  * encounters an error or is unlinked.  An unlinked isochronous URB may
568  * leave a gap in the stream of packets; it is undefined whether such
569  * gaps can be filled in.
570  *
571  * Note that early termination of an URB because a short packet was
572  * received will generate a -EREMOTEIO error if and only if the
573  * URB_SHORT_NOT_OK flag is set.  By setting this flag, USB device
574  * drivers can build deep queues for large or complex bulk transfers
575  * and clean them up reliably after any sort of aborted transfer by
576  * unlinking all pending URBs at the first fault.
577  *
578  * When a control URB terminates with an error other than -EREMOTEIO, it
579  * is quite likely that the status stage of the transfer will not take
580  * place.
581  */
usb_unlink_urb(struct urb * urb)582 int usb_unlink_urb(struct urb *urb)
583 {
584 	if (!urb)
585 		return -EINVAL;
586 	if (!urb->dev)
587 		return -ENODEV;
588 	if (!urb->ep)
589 		return -EIDRM;
590 	return usb_hcd_unlink_urb(urb, -ECONNRESET);
591 }
592 EXPORT_SYMBOL_GPL(usb_unlink_urb);
593 
594 /**
595  * usb_kill_urb - cancel a transfer request and wait for it to finish
596  * @urb: pointer to URB describing a previously submitted request,
597  *	may be NULL
598  *
599  * This routine cancels an in-progress request.  It is guaranteed that
600  * upon return all completion handlers will have finished and the URB
601  * will be totally idle and available for reuse.  These features make
602  * this an ideal way to stop I/O in a disconnect() callback or close()
603  * function.  If the request has not already finished or been unlinked
604  * the completion handler will see urb->status == -ENOENT.
605  *
606  * While the routine is running, attempts to resubmit the URB will fail
607  * with error -EPERM.  Thus even if the URB's completion handler always
608  * tries to resubmit, it will not succeed and the URB will become idle.
609  *
610  * The URB must not be deallocated while this routine is running.  In
611  * particular, when a driver calls this routine, it must insure that the
612  * completion handler cannot deallocate the URB.
613  *
614  * This routine may not be used in an interrupt context (such as a bottom
615  * half or a completion handler), or when holding a spinlock, or in other
616  * situations where the caller can't schedule().
617  *
618  * This routine should not be called by a driver after its disconnect
619  * method has returned.
620  */
usb_kill_urb(struct urb * urb)621 void usb_kill_urb(struct urb *urb)
622 {
623 	might_sleep();
624 	if (!(urb && urb->dev && urb->ep))
625 		return;
626 	atomic_inc(&urb->reject);
627 
628 	usb_hcd_unlink_urb(urb, -ENOENT);
629 	wait_event(usb_kill_urb_queue, atomic_read(&urb->use_count) == 0);
630 
631 	atomic_dec(&urb->reject);
632 }
633 EXPORT_SYMBOL_GPL(usb_kill_urb);
634 
635 /**
636  * usb_poison_urb - reliably kill a transfer and prevent further use of an URB
637  * @urb: pointer to URB describing a previously submitted request,
638  *	may be NULL
639  *
640  * This routine cancels an in-progress request.  It is guaranteed that
641  * upon return all completion handlers will have finished and the URB
642  * will be totally idle and cannot be reused.  These features make
643  * this an ideal way to stop I/O in a disconnect() callback.
644  * If the request has not already finished or been unlinked
645  * the completion handler will see urb->status == -ENOENT.
646  *
647  * After and while the routine runs, attempts to resubmit the URB will fail
648  * with error -EPERM.  Thus even if the URB's completion handler always
649  * tries to resubmit, it will not succeed and the URB will become idle.
650  *
651  * The URB must not be deallocated while this routine is running.  In
652  * particular, when a driver calls this routine, it must insure that the
653  * completion handler cannot deallocate the URB.
654  *
655  * This routine may not be used in an interrupt context (such as a bottom
656  * half or a completion handler), or when holding a spinlock, or in other
657  * situations where the caller can't schedule().
658  *
659  * This routine should not be called by a driver after its disconnect
660  * method has returned.
661  */
usb_poison_urb(struct urb * urb)662 void usb_poison_urb(struct urb *urb)
663 {
664 	might_sleep();
665 	if (!(urb && urb->dev && urb->ep))
666 		return;
667 	atomic_inc(&urb->reject);
668 
669 	usb_hcd_unlink_urb(urb, -ENOENT);
670 	wait_event(usb_kill_urb_queue, atomic_read(&urb->use_count) == 0);
671 }
672 EXPORT_SYMBOL_GPL(usb_poison_urb);
673 
usb_unpoison_urb(struct urb * urb)674 void usb_unpoison_urb(struct urb *urb)
675 {
676 	if (!urb)
677 		return;
678 
679 	atomic_dec(&urb->reject);
680 }
681 EXPORT_SYMBOL_GPL(usb_unpoison_urb);
682 
683 /**
684  * usb_block_urb - reliably prevent further use of an URB
685  * @urb: pointer to URB to be blocked, may be NULL
686  *
687  * After the routine has run, 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.
690  *
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.
694  */
usb_block_urb(struct urb * urb)695 void usb_block_urb(struct urb *urb)
696 {
697 	if (!urb)
698 		return;
699 
700 	atomic_inc(&urb->reject);
701 }
702 EXPORT_SYMBOL_GPL(usb_block_urb);
703 
704 /**
705  * usb_kill_anchored_urbs - cancel transfer requests en masse
706  * @anchor: anchor the requests are bound to
707  *
708  * this allows all outstanding URBs to be killed starting
709  * from the back of the queue
710  *
711  * This routine should not be called by a driver after its disconnect
712  * method has returned.
713  */
usb_kill_anchored_urbs(struct usb_anchor * anchor)714 void usb_kill_anchored_urbs(struct usb_anchor *anchor)
715 {
716 	struct urb *victim;
717 
718 	spin_lock_irq(&anchor->lock);
719 	while (!list_empty(&anchor->urb_list)) {
720 		victim = list_entry(anchor->urb_list.prev, struct urb,
721 				    anchor_list);
722 		/* we must make sure the URB isn't freed before we kill it*/
723 		usb_get_urb(victim);
724 		spin_unlock_irq(&anchor->lock);
725 		/* this will unanchor the URB */
726 		usb_kill_urb(victim);
727 		usb_put_urb(victim);
728 		spin_lock_irq(&anchor->lock);
729 	}
730 	spin_unlock_irq(&anchor->lock);
731 }
732 EXPORT_SYMBOL_GPL(usb_kill_anchored_urbs);
733 
734 
735 /**
736  * usb_poison_anchored_urbs - cease all traffic from an anchor
737  * @anchor: anchor the requests are bound to
738  *
739  * this allows all outstanding URBs to be poisoned starting
740  * from the back of the queue. Newly added URBs will also be
741  * poisoned
742  *
743  * This routine should not be called by a driver after its disconnect
744  * method has returned.
745  */
usb_poison_anchored_urbs(struct usb_anchor * anchor)746 void usb_poison_anchored_urbs(struct usb_anchor *anchor)
747 {
748 	struct urb *victim;
749 
750 	spin_lock_irq(&anchor->lock);
751 	anchor->poisoned = 1;
752 	while (!list_empty(&anchor->urb_list)) {
753 		victim = list_entry(anchor->urb_list.prev, struct urb,
754 				    anchor_list);
755 		/* we must make sure the URB isn't freed before we kill it*/
756 		usb_get_urb(victim);
757 		spin_unlock_irq(&anchor->lock);
758 		/* this will unanchor the URB */
759 		usb_poison_urb(victim);
760 		usb_put_urb(victim);
761 		spin_lock_irq(&anchor->lock);
762 	}
763 	spin_unlock_irq(&anchor->lock);
764 }
765 EXPORT_SYMBOL_GPL(usb_poison_anchored_urbs);
766 
767 /**
768  * usb_unpoison_anchored_urbs - let an anchor be used successfully again
769  * @anchor: anchor the requests are bound to
770  *
771  * Reverses the effect of usb_poison_anchored_urbs
772  * the anchor can be used normally after it returns
773  */
usb_unpoison_anchored_urbs(struct usb_anchor * anchor)774 void usb_unpoison_anchored_urbs(struct usb_anchor *anchor)
775 {
776 	unsigned long flags;
777 	struct urb *lazarus;
778 
779 	spin_lock_irqsave(&anchor->lock, flags);
780 	list_for_each_entry(lazarus, &anchor->urb_list, anchor_list) {
781 		usb_unpoison_urb(lazarus);
782 	}
783 	anchor->poisoned = 0;
784 	spin_unlock_irqrestore(&anchor->lock, flags);
785 }
786 EXPORT_SYMBOL_GPL(usb_unpoison_anchored_urbs);
787 /**
788  * usb_unlink_anchored_urbs - asynchronously cancel transfer requests en masse
789  * @anchor: anchor the requests are bound to
790  *
791  * this allows all outstanding URBs to be unlinked starting
792  * from the back of the queue. This function is asynchronous.
793  * The unlinking is just tiggered. It may happen after this
794  * function has returned.
795  *
796  * This routine should not be called by a driver after its disconnect
797  * method has returned.
798  */
usb_unlink_anchored_urbs(struct usb_anchor * anchor)799 void usb_unlink_anchored_urbs(struct usb_anchor *anchor)
800 {
801 	struct urb *victim;
802 
803 	while ((victim = usb_get_from_anchor(anchor)) != NULL) {
804 		usb_unlink_urb(victim);
805 		usb_put_urb(victim);
806 	}
807 }
808 EXPORT_SYMBOL_GPL(usb_unlink_anchored_urbs);
809 
810 /**
811  * usb_wait_anchor_empty_timeout - wait for an anchor to be unused
812  * @anchor: the anchor you want to become unused
813  * @timeout: how long you are willing to wait in milliseconds
814  *
815  * Call this is you want to be sure all an anchor's
816  * URBs have finished
817  */
usb_wait_anchor_empty_timeout(struct usb_anchor * anchor,unsigned int timeout)818 int usb_wait_anchor_empty_timeout(struct usb_anchor *anchor,
819 				  unsigned int timeout)
820 {
821 	return wait_event_timeout(anchor->wait, list_empty(&anchor->urb_list),
822 				  msecs_to_jiffies(timeout));
823 }
824 EXPORT_SYMBOL_GPL(usb_wait_anchor_empty_timeout);
825 
826 /**
827  * usb_get_from_anchor - get an anchor's oldest urb
828  * @anchor: the anchor whose urb you want
829  *
830  * this will take the oldest urb from an anchor,
831  * unanchor and return it
832  */
usb_get_from_anchor(struct usb_anchor * anchor)833 struct urb *usb_get_from_anchor(struct usb_anchor *anchor)
834 {
835 	struct urb *victim;
836 	unsigned long flags;
837 
838 	spin_lock_irqsave(&anchor->lock, flags);
839 	if (!list_empty(&anchor->urb_list)) {
840 		victim = list_entry(anchor->urb_list.next, struct urb,
841 				    anchor_list);
842 		usb_get_urb(victim);
843 		__usb_unanchor_urb(victim, anchor);
844 	} else {
845 		victim = NULL;
846 	}
847 	spin_unlock_irqrestore(&anchor->lock, flags);
848 
849 	return victim;
850 }
851 
852 EXPORT_SYMBOL_GPL(usb_get_from_anchor);
853 
854 /**
855  * usb_scuttle_anchored_urbs - unanchor all an anchor's urbs
856  * @anchor: the anchor whose urbs you want to unanchor
857  *
858  * use this to get rid of all an anchor's urbs
859  */
usb_scuttle_anchored_urbs(struct usb_anchor * anchor)860 void usb_scuttle_anchored_urbs(struct usb_anchor *anchor)
861 {
862 	struct urb *victim;
863 	unsigned long flags;
864 
865 	spin_lock_irqsave(&anchor->lock, flags);
866 	while (!list_empty(&anchor->urb_list)) {
867 		victim = list_entry(anchor->urb_list.prev, struct urb,
868 				    anchor_list);
869 		__usb_unanchor_urb(victim, anchor);
870 	}
871 	spin_unlock_irqrestore(&anchor->lock, flags);
872 }
873 
874 EXPORT_SYMBOL_GPL(usb_scuttle_anchored_urbs);
875 
876 /**
877  * usb_anchor_empty - is an anchor empty
878  * @anchor: the anchor you want to query
879  *
880  * returns 1 if the anchor has no urbs associated with it
881  */
usb_anchor_empty(struct usb_anchor * anchor)882 int usb_anchor_empty(struct usb_anchor *anchor)
883 {
884 	return list_empty(&anchor->urb_list);
885 }
886 
887 EXPORT_SYMBOL_GPL(usb_anchor_empty);
888 
889