Initial import

1 files changed, 969 insertions, 0 deletions

diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c
new file mode 100644
index 000000000..c9e8ee81b
--- /dev/null
+++ b/drivers/usb/core/urb.c
@@ -0,0 +1,969 @@
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/bitops.h>
+#include <linux/slab.h>
+#include <linux/log2.h>
+#include <linux/usb.h>
+#include <linux/wait.h>
+#include <linux/usb/hcd.h>
+#include <linux/scatterlist.h>
+
+#define to_urb(d) container_of(d, struct urb, kref)
+
+
+static void urb_destroy(struct kref *kref)
+{
+	struct urb *urb = to_urb(kref);
+
+	if (urb->transfer_flags & URB_FREE_BUFFER)
+		kfree(urb->transfer_buffer);
+
+	kfree(urb);
+}
+
+/**
+ * usb_init_urb - initializes a urb so that it can be used by a USB driver
+ * @urb: pointer to the urb to initialize
+ *
+ * Initializes a urb so that the USB subsystem can use it properly.
+ *
+ * If a urb is created with a call to usb_alloc_urb() it is not
+ * necessary to call this function.  Only use this if you allocate the
+ * space for a struct urb on your own.  If you call this function, be
+ * careful when freeing the memory for your urb that it is no longer in
+ * use by the USB core.
+ *
+ * Only use this function if you _really_ understand what you are doing.
+ */
+void usb_init_urb(struct urb *urb)
+{
+	if (urb) {
+		memset(urb, 0, sizeof(*urb));
+		kref_init(&urb->kref);
+		INIT_LIST_HEAD(&urb->anchor_list);
+	}
+}
+EXPORT_SYMBOL_GPL(usb_init_urb);
+
+/**
+ * usb_alloc_urb - creates a new urb for a USB driver to use
+ * @iso_packets: number of iso packets for this urb
+ * @mem_flags: the type of memory to allocate, see kmalloc() for a list of
+ *	valid options for this.
+ *
+ * Creates an urb for the USB driver to use, initializes a few internal
+ * structures, increments the usage counter, and returns a pointer to it.
+ *
+ * If the driver want to use this urb for interrupt, control, or bulk
+ * endpoints, pass '0' as the number of iso packets.
+ *
+ * The driver must call usb_free_urb() when it is finished with the urb.
+ *
+ * Return: A pointer to the new urb, or %NULL if no memory is available.
+ */
+struct urb *usb_alloc_urb(int iso_packets, gfp_t mem_flags)
+{
+	struct urb *urb;
+
+	urb = kmalloc(sizeof(struct urb) +
+		iso_packets * sizeof(struct usb_iso_packet_descriptor),
+		mem_flags);
+	if (!urb) {
+		printk(KERN_ERR "alloc_urb: kmalloc failed\n");
+		return NULL;
+	}
+	usb_init_urb(urb);
+	return urb;
+}
+EXPORT_SYMBOL_GPL(usb_alloc_urb);
+
+/**
+ * usb_free_urb - frees the memory used by a urb when all users of it are finished
+ * @urb: pointer to the urb to free, may be NULL
+ *
+ * Must be called when a user of a urb is finished with it.  When the last user
+ * of the urb calls this function, the memory of the urb is freed.
+ *
+ * Note: The transfer buffer associated with the urb is not freed unless the
+ * URB_FREE_BUFFER transfer flag is set.
+ */
+void usb_free_urb(struct urb *urb)
+{
+	if (urb)
+		kref_put(&urb->kref, urb_destroy);
+}
+EXPORT_SYMBOL_GPL(usb_free_urb);
+
+/**
+ * usb_get_urb - increments the reference count of the urb
+ * @urb: pointer to the urb to modify, may be NULL
+ *
+ * This must be  called whenever a urb is transferred from a device driver to a
+ * host controller driver.  This allows proper reference counting to happen
+ * for urbs.
+ *
+ * Return: A pointer to the urb with the incremented reference counter.
+ */
+struct urb *usb_get_urb(struct urb *urb)
+{
+	if (urb)
+		kref_get(&urb->kref);
+	return urb;
+}
+EXPORT_SYMBOL_GPL(usb_get_urb);
+
+/**
+ * usb_anchor_urb - anchors an URB while it is processed
+ * @urb: pointer to the urb to anchor
+ * @anchor: pointer to the anchor
+ *
+ * This can be called to have access to URBs which are to be executed
+ * without bothering to track them
+ */
+void usb_anchor_urb(struct urb *urb, struct usb_anchor *anchor)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&anchor->lock, flags);
+	usb_get_urb(urb);
+	list_add_tail(&urb->anchor_list, &anchor->urb_list);
+	urb->anchor = anchor;
+
+	if (unlikely(anchor->poisoned)) {
+		atomic_inc(&urb->reject);
+	}
+
+	spin_unlock_irqrestore(&anchor->lock, flags);
+}
+EXPORT_SYMBOL_GPL(usb_anchor_urb);
+
+static int usb_anchor_check_wakeup(struct usb_anchor *anchor)
+{
+	return atomic_read(&anchor->suspend_wakeups) == 0 &&
+		list_empty(&anchor->urb_list);
+}
+
+/* Callers must hold anchor->lock */
+static void __usb_unanchor_urb(struct urb *urb, struct usb_anchor *anchor)
+{
+	urb->anchor = NULL;
+	list_del(&urb->anchor_list);
+	usb_put_urb(urb);
+	if (usb_anchor_check_wakeup(anchor))
+		wake_up(&anchor->wait);
+}
+
+/**
+ * usb_unanchor_urb - unanchors an URB
+ * @urb: pointer to the urb to anchor
+ *
+ * Call this to stop the system keeping track of this URB
+ */
+void usb_unanchor_urb(struct urb *urb)
+{
+	unsigned long flags;
+	struct usb_anchor *anchor;
+
+	if (!urb)
+		return;
+
+	anchor = urb->anchor;
+	if (!anchor)
+		return;
+
+	spin_lock_irqsave(&anchor->lock, flags);
+	/*
+	 * At this point, we could be competing with another thread which
+	 * has the same intention. To protect the urb from being unanchored
+	 * twice, only the winner of the race gets the job.
+	 */
+	if (likely(anchor == urb->anchor))
+		__usb_unanchor_urb(urb, anchor);
+	spin_unlock_irqrestore(&anchor->lock, flags);
+}
+EXPORT_SYMBOL_GPL(usb_unanchor_urb);
+
+/*-------------------------------------------------------------------*/
+
+/**
+ * usb_submit_urb - issue an asynchronous transfer request for an endpoint
+ * @urb: pointer to the urb describing the request
+ * @mem_flags: the type of memory to allocate, see kmalloc() for a list
+ *	of valid options for this.
+ *
+ * This submits a transfer request, and transfers control of the URB
+ * describing that request to the USB subsystem.  Request completion will
+ * be indicated later, asynchronously, by calling the completion handler.
+ * The three types of completion are success, error, and unlink
+ * (a software-induced fault, also called "request cancellation").
+ *
+ * URBs may be submitted in interrupt context.
+ *
+ * The caller must have correctly initialized the URB before submitting
+ * it.  Functions such as usb_fill_bulk_urb() and usb_fill_control_urb() are
+ * available to ensure that most fields are correctly initialized, for
+ * the particular kind of transfer, although they will not initialize
+ * any transfer flags.
+ *
+ * If the submission is successful, the complete() callback from the URB
+ * will be called exactly once, when the USB core and Host Controller Driver
+ * (HCD) are finished with the URB.  When the completion function is called,
+ * control of the URB is returned to the device driver which issued the
+ * request.  The completion handler may then immediately free or reuse that
+ * URB.
+ *
+ * With few exceptions, USB device drivers should never access URB fields
+ * provided by usbcore or the HCD until its complete() is called.
+ * The exceptions relate to periodic transfer scheduling.  For both
+ * interrupt and isochronous urbs, as part of successful URB submission
+ * urb->interval is modified to reflect the actual transfer period used
+ * (normally some power of two units).  And for isochronous urbs,
+ * urb->start_frame is modified to reflect when the URB's transfers were
+ * scheduled to start.
+ *
+ * Not all isochronous transfer scheduling policies will work, but most
+ * host controller drivers should easily handle ISO queues going from now
+ * until 10-200 msec into the future.  Drivers should try to keep at
+ * least one or two msec of data in the queue; many controllers require
+ * that new transfers start at least 1 msec in the future when they are
+ * added.  If the driver is unable to keep up and the queue empties out,
+ * the behavior for new submissions is governed by the URB_ISO_ASAP flag.
+ * If the flag is set, or if the queue is idle, then the URB is always
+ * assigned to the first available (and not yet expired) slot in the
+ * endpoint's schedule.  If the flag is not set and the queue is active
+ * then the URB is always assigned to the next slot in the schedule
+ * following the end of the endpoint's previous URB, even if that slot is
+ * in the past.  When a packet is assigned in this way to a slot that has
+ * already expired, the packet is not transmitted and the corresponding
+ * usb_iso_packet_descriptor's status field will return -EXDEV.  If this
+ * would happen to all the packets in the URB, submission fails with a
+ * -EXDEV error code.
+ *
+ * For control endpoints, the synchronous usb_control_msg() call is
+ * often used (in non-interrupt context) instead of this call.
+ * That is often used through convenience wrappers, for the requests
+ * that are standardized in the USB 2.0 specification.  For bulk
+ * endpoints, a synchronous usb_bulk_msg() call is available.
+ *
+ * Return:
+ * 0 on successful submissions. A negative error number otherwise.
+ *
+ * Request Queuing:
+ *
+ * URBs may be submitted to endpoints before previous ones complete, to
+ * minimize the impact of interrupt latencies and system overhead on data
+ * throughput.  With that queuing policy, an endpoint's queue would never
+ * be empty.  This is required for continuous isochronous data streams,
+ * and may also be required for some kinds of interrupt transfers. Such
+ * queuing also maximizes bandwidth utilization by letting USB controllers
+ * start work on later requests before driver software has finished the
+ * completion processing for earlier (successful) requests.
+ *
+ * As of Linux 2.6, all USB endpoint transfer queues support depths greater
+ * than one.  This was previously a HCD-specific behavior, except for ISO
+ * transfers.  Non-isochronous endpoint queues are inactive during cleanup
+ * after faults (transfer errors or cancellation).
+ *
+ * Reserved Bandwidth Transfers:
+ *
+ * Periodic transfers (interrupt or isochronous) are performed repeatedly,
+ * using the interval specified in the urb.  Submitting the first urb to
+ * the endpoint reserves the bandwidth necessary to make those transfers.
+ * If the USB subsystem can't allocate sufficient bandwidth to perform
+ * the periodic request, submitting such a periodic request should fail.
+ *
+ * For devices under xHCI, the bandwidth is reserved at configuration time, or
+ * when the alt setting is selected.  If there is not enough bus bandwidth, the
+ * configuration/alt setting request will fail.  Therefore, submissions to
+ * periodic endpoints on devices under xHCI should never fail due to bandwidth
+ * constraints.
+ *
+ * Device drivers must explicitly request that repetition, by ensuring that
+ * some URB is always on the endpoint's queue (except possibly for short
+ * periods during completion callbacks).  When there is no longer an urb
+ * queued, the endpoint's bandwidth reservation is canceled.  This means
+ * drivers can use their completion handlers to ensure they keep bandwidth
+ * they need, by reinitializing and resubmitting the just-completed urb
+ * until the driver longer needs that periodic bandwidth.
+ *
+ * Memory Flags:
+ *
+ * The general rules for how to decide which mem_flags to use
+ * are the same as for kmalloc.  There are four
+ * different possible values; GFP_KERNEL, GFP_NOFS, GFP_NOIO and
+ * GFP_ATOMIC.
+ *
+ * GFP_NOFS is not ever used, as it has not been implemented yet.
+ *
+ * GFP_ATOMIC is used when
+ *   (a) you are inside a completion handler, an interrupt, bottom half,
+ *       tasklet or timer, or
+ *   (b) you are holding a spinlock or rwlock (does not apply to
+ *       semaphores), or
+ *   (c) current->state != TASK_RUNNING, this is the case only after
+ *       you've changed it.
+ *
+ * GFP_NOIO is used in the block io path and error handling of storage
+ * devices.
+ *
+ * All other situations use GFP_KERNEL.
+ *
+ * Some more specific rules for mem_flags can be inferred, such as
+ *  (1) start_xmit, timeout, and receive methods of network drivers must
+ *      use GFP_ATOMIC (they are called with a spinlock held);
+ *  (2) queuecommand methods of scsi drivers must use GFP_ATOMIC (also
+ *      called with a spinlock held);
+ *  (3) If you use a kernel thread with a network driver you must use
+ *      GFP_NOIO, unless (b) or (c) apply;
+ *  (4) after you have done a down() you can use GFP_KERNEL, unless (b) or (c)
+ *      apply or your are in a storage driver's block io path;
+ *  (5) USB probe and disconnect can use GFP_KERNEL unless (b) or (c) apply; and
+ *  (6) changing firmware on a running storage or net device uses
+ *      GFP_NOIO, unless b) or c) apply
+ *
+ */
+int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
+{
+	static int			pipetypes[4] = {
+		PIPE_CONTROL, PIPE_ISOCHRONOUS, PIPE_BULK, PIPE_INTERRUPT
+	};
+	int				xfertype, max;
+	struct usb_device		*dev;
+	struct usb_host_endpoint	*ep;
+	int				is_out;
+	unsigned int			allowed;
+
+	if (!urb || !urb->complete)
+		return -EINVAL;
+	if (urb->hcpriv) {
+		WARN_ONCE(1, "URB %p submitted while active\n", urb);
+		return -EBUSY;
+	}
+
+	dev = urb->dev;
+	if ((!dev) || (dev->state < USB_STATE_UNAUTHENTICATED))
+		return -ENODEV;
+
+	/* For now, get the endpoint from the pipe.  Eventually drivers
+	 * will be required to set urb->ep directly and we will eliminate
+	 * urb->pipe.
+	 */
+	ep = usb_pipe_endpoint(dev, urb->pipe);
+	if (!ep)
+		return -ENOENT;
+
+	urb->ep = ep;
+	urb->status = -EINPROGRESS;
+	urb->actual_length = 0;
+
+	/* Lots of sanity checks, so HCDs can rely on clean data
+	 * and don't need to duplicate tests
+	 */
+	xfertype = usb_endpoint_type(&ep->desc);
+	if (xfertype == USB_ENDPOINT_XFER_CONTROL) {
+		struct usb_ctrlrequest *setup =
+				(struct usb_ctrlrequest *) urb->setup_packet;
+
+		if (!setup)
+			return -ENOEXEC;
+		is_out = !(setup->bRequestType & USB_DIR_IN) ||
+				!setup->wLength;
+	} else {
+		is_out = usb_endpoint_dir_out(&ep->desc);
+	}
+
+	/* Clear the internal flags and cache the direction for later use */
+	urb->transfer_flags &= ~(URB_DIR_MASK | URB_DMA_MAP_SINGLE |
+			URB_DMA_MAP_PAGE | URB_DMA_MAP_SG | URB_MAP_LOCAL |
+			URB_SETUP_MAP_SINGLE | URB_SETUP_MAP_LOCAL |
+			URB_DMA_SG_COMBINED);
+	urb->transfer_flags |= (is_out ? URB_DIR_OUT : URB_DIR_IN);
+
+	if (xfertype != USB_ENDPOINT_XFER_CONTROL &&
+			dev->state < USB_STATE_CONFIGURED)
+		return -ENODEV;
+
+	max = usb_endpoint_maxp(&ep->desc);
+	if (max <= 0) {
+		dev_dbg(&dev->dev,
+			"bogus endpoint ep%d%s in %s (bad maxpacket %d)\n",
+			usb_endpoint_num(&ep->desc), is_out ? "out" : "in",
+			__func__, max);
+		return -EMSGSIZE;
+	}
+
+	/* periodic transfers limit size per frame/uframe,
+	 * but drivers only control those sizes for ISO.
+	 * while we're checking, initialize return status.
+	 */
+	if (xfertype == USB_ENDPOINT_XFER_ISOC) {
+		int	n, len;
+
+		/* SuperSpeed isoc endpoints have up to 16 bursts of up to
+		 * 3 packets each
+		 */
+		if (dev->speed == USB_SPEED_SUPER) {
+			int     burst = 1 + ep->ss_ep_comp.bMaxBurst;
+			int     mult = USB_SS_MULT(ep->ss_ep_comp.bmAttributes);
+			max *= burst;
+			max *= mult;
+		}
+
+		/* "high bandwidth" mode, 1-3 packets/uframe? */
+		if (dev->speed == USB_SPEED_HIGH) {
+			int	mult = 1 + ((max >> 11) & 0x03);
+			max &= 0x07ff;
+			max *= mult;
+		}
+
+		if (urb->number_of_packets <= 0)
+			return -EINVAL;
+		for (n = 0; n < urb->number_of_packets; n++) {
+			len = urb->iso_frame_desc[n].length;
+			if (len < 0 || len > max)
+				return -EMSGSIZE;
+			urb->iso_frame_desc[n].status = -EXDEV;
+			urb->iso_frame_desc[n].actual_length = 0;
+		}
+	} else if (urb->num_sgs && !urb->dev->bus->no_sg_constraint &&
+			dev->speed != USB_SPEED_WIRELESS) {
+		struct scatterlist *sg;
+		int i;
+
+		for_each_sg(urb->sg, sg, urb->num_sgs - 1, i)
+			if (sg->length % max)
+				return -EINVAL;
+	}
+
+	/* the I/O buffer must be mapped/unmapped, except when length=0 */
+	if (urb->transfer_buffer_length > INT_MAX)
+		return -EMSGSIZE;
+
+	/*
+	 * stuff that drivers shouldn't do, but which shouldn't
+	 * cause problems in HCDs if they get it wrong.
+	 */
+
+	/* Check that the pipe's type matches the endpoint's type */
+	if (usb_pipetype(urb->pipe) != pipetypes[xfertype])
+		dev_WARN(&dev->dev, "BOGUS urb xfer, pipe %x != type %x\n",
+			usb_pipetype(urb->pipe), pipetypes[xfertype]);
+
+	/* Check against a simple/standard policy */
+	allowed = (URB_NO_TRANSFER_DMA_MAP | URB_NO_INTERRUPT | URB_DIR_MASK |
+			URB_FREE_BUFFER);
+	switch (xfertype) {
+	case USB_ENDPOINT_XFER_BULK:
+	case USB_ENDPOINT_XFER_INT:
+		if (is_out)
+			allowed |= URB_ZERO_PACKET;
+		/* FALLTHROUGH */
+	case USB_ENDPOINT_XFER_CONTROL:
+		allowed |= URB_NO_FSBR;	/* only affects UHCI */
+		/* FALLTHROUGH */
+	default:			/* all non-iso endpoints */
+		if (!is_out)
+			allowed |= URB_SHORT_NOT_OK;
+		break;
+	case USB_ENDPOINT_XFER_ISOC:
+		allowed |= URB_ISO_ASAP;
+		break;
+	}
+	allowed &= urb->transfer_flags;
+
+	/* warn if submitter gave bogus flags */
+	if (allowed != urb->transfer_flags)
+		dev_WARN(&dev->dev, "BOGUS urb flags, %x --> %x\n",
+			urb->transfer_flags, allowed);
+
+	/*
+	 * Force periodic transfer intervals to be legal values that are
+	 * a power of two (so HCDs don't need to).
+	 *
+	 * FIXME want bus->{intr,iso}_sched_horizon values here.  Each HC
+	 * supports different values... this uses EHCI/UHCI defaults (and
+	 * EHCI can use smaller non-default values).
+	 */
+	switch (xfertype) {
+	case USB_ENDPOINT_XFER_ISOC:
+	case USB_ENDPOINT_XFER_INT:
+		/* too small? */
+		switch (dev->speed) {
+		case USB_SPEED_WIRELESS:
+			if ((urb->interval < 6)
+				&& (xfertype == USB_ENDPOINT_XFER_INT))
+				return -EINVAL;
+		default:
+			if (urb->interval <= 0)
+				return -EINVAL;
+			break;
+		}
+		/* too big? */
+		switch (dev->speed) {
+		case USB_SPEED_SUPER:	/* units are 125us */
+			/* Handle up to 2^(16-1) microframes */
+			if (urb->interval > (1 << 15))
+				return -EINVAL;
+			max = 1 << 15;
+			break;
+		case USB_SPEED_WIRELESS:
+			if (urb->interval > 16)
+				return -EINVAL;
+			break;
+		case USB_SPEED_HIGH:	/* units are microframes */
+			/* NOTE usb handles 2^15 */
+			if (urb->interval > (1024 * 8))
+				urb->interval = 1024 * 8;
+			max = 1024 * 8;
+			break;
+		case USB_SPEED_FULL:	/* units are frames/msec */
+		case USB_SPEED_LOW:
+			if (xfertype == USB_ENDPOINT_XFER_INT) {
+				if (urb->interval > 255)
+					return -EINVAL;
+				/* NOTE ohci only handles up to 32 */
+				max = 128;
+			} else {
+				if (urb->interval > 1024)
+					urb->interval = 1024;
+				/* NOTE usb and ohci handle up to 2^15 */
+				max = 1024;
+			}
+			break;
+		default:
+			return -EINVAL;
+		}
+		if (dev->speed != USB_SPEED_WIRELESS) {
+			/* Round down to a power of 2, no more than max */
+			urb->interval = min(max, 1 << ilog2(urb->interval));
+		}
+	}
+
+	return usb_hcd_submit_urb(urb, mem_flags);
+}
+EXPORT_SYMBOL_GPL(usb_submit_urb);
+
+/*-------------------------------------------------------------------*/
+
+/**
+ * usb_unlink_urb - abort/cancel a transfer request for an endpoint
+ * @urb: pointer to urb describing a previously submitted request,
+ *	may be NULL
+ *
+ * This routine cancels an in-progress request.  URBs complete only once
+ * per submission, and may be canceled only once per submission.
+ * Successful cancellation means termination of @urb will be expedited
+ * and the completion handler will be called with a status code
+ * indicating that the request has been canceled (rather than any other
+ * code).
+ *
+ * Drivers should not call this routine or related routines, such as
+ * usb_kill_urb() or usb_unlink_anchored_urbs(), after their disconnect
+ * method has returned.  The disconnect function should synchronize with
+ * a driver's I/O routines to insure that all URB-related activity has
+ * completed before it returns.
+ *
+ * This request is asynchronous, however the HCD might call the ->complete()
+ * callback during unlink. Therefore when drivers call usb_unlink_urb(), they
+ * must not hold any locks that may be taken by the completion function.
+ * Success is indicated by returning -EINPROGRESS, at which time the URB will
+ * probably not yet have been given back to the device driver. When it is
+ * eventually called, the completion function will see @urb->status ==
+ * -ECONNRESET.
+ * Failure is indicated by usb_unlink_urb() returning any other value.
+ * Unlinking will fail when @urb is not currently "linked" (i.e., it was
+ * never submitted, or it was unlinked before, or the hardware is already
+ * finished with it), even if the completion handler has not yet run.
+ *
+ * The URB must not be deallocated while this routine is running.  In
+ * particular, when a driver calls this routine, it must insure that the
+ * completion handler cannot deallocate the URB.
+ *
+ * Return: -EINPROGRESS on success. See description for other values on
+ * failure.
+ *
+ * Unlinking and Endpoint Queues:
+ *
+ * [The behaviors and guarantees described below do not apply to virtual
+ * root hubs but only to endpoint queues for physical USB devices.]
+ *
+ * Host Controller Drivers (HCDs) place all the URBs for a particular
+ * endpoint in a queue.  Normally the queue advances as the controller
+ * hardware processes each request.  But when an URB terminates with an
+ * error its queue generally stops (see below), at least until that URB's
+ * completion routine returns.  It is guaranteed that a stopped queue
+ * will not restart until all its unlinked URBs have been fully retired,
+ * with their completion routines run, even if that's not until some time
+ * after the original completion handler returns.  The same behavior and
+ * guarantee apply when an URB terminates because it was unlinked.
+ *
+ * Bulk and interrupt endpoint queues are guaranteed to stop whenever an
+ * URB terminates with any sort of error, including -ECONNRESET, -ENOENT,
+ * and -EREMOTEIO.  Control endpoint queues behave the same way except
+ * that they are not guaranteed to stop for -EREMOTEIO errors.  Queues
+ * for isochronous endpoints are treated differently, because they must
+ * advance at fixed rates.  Such queues do not stop when an URB
+ * encounters an error or is unlinked.  An unlinked isochronous URB may
+ * leave a gap in the stream of packets; it is undefined whether such
+ * gaps can be filled in.
+ *
+ * Note that early termination of an URB because a short packet was
+ * received will generate a -EREMOTEIO error if and only if the
+ * URB_SHORT_NOT_OK flag is set.  By setting this flag, USB device
+ * drivers can build deep queues for large or complex bulk transfers
+ * and clean them up reliably after any sort of aborted transfer by
+ * unlinking all pending URBs at the first fault.
+ *
+ * When a control URB terminates with an error other than -EREMOTEIO, it
+ * is quite likely that the status stage of the transfer will not take
+ * place.
+ */
+int usb_unlink_urb(struct urb *urb)
+{
+	if (!urb)
+		return -EINVAL;
+	if (!urb->dev)
+		return -ENODEV;
+	if (!urb->ep)
+		return -EIDRM;
+	return usb_hcd_unlink_urb(urb, -ECONNRESET);
+}
+EXPORT_SYMBOL_GPL(usb_unlink_urb);
+
+/**
+ * usb_kill_urb - cancel a transfer request and wait for it to finish
+ * @urb: pointer to URB describing a previously submitted request,
+ *	may be NULL
+ *
+ * This routine cancels an in-progress request.  It is guaranteed that
+ * upon return all completion handlers will have finished and the URB
+ * will be totally idle and available for reuse.  These features make
+ * this an ideal way to stop I/O in a disconnect() callback or close()
+ * function.  If the request has not already finished or been unlinked
+ * the completion handler will see urb->status == -ENOENT.
+ *
+ * While the routine is running, attempts to resubmit the URB will fail
+ * with error -EPERM.  Thus even if the URB's completion handler always
+ * tries to resubmit, it will not succeed and the URB will become idle.
+ *
+ * The URB must not be deallocated while this routine is running.  In
+ * particular, when a driver calls this routine, it must insure that the
+ * completion handler cannot deallocate the URB.
+ *
+ * This routine may not be used in an interrupt context (such as a bottom
+ * half or a completion handler), or when holding a spinlock, or in other
+ * situations where the caller can't schedule().
+ *
+ * This routine should not be called by a driver after its disconnect
+ * method has returned.
+ */
+void usb_kill_urb(struct urb *urb)
+{
+	might_sleep();
+	if (!(urb && urb->dev && urb->ep))
+		return;
+	atomic_inc(&urb->reject);
+
+	usb_hcd_unlink_urb(urb, -ENOENT);
+	wait_event(usb_kill_urb_queue, atomic_read(&urb->use_count) == 0);
+
+	atomic_dec(&urb->reject);
+}
+EXPORT_SYMBOL_GPL(usb_kill_urb);
+
+/**
+ * usb_poison_urb - reliably kill a transfer and prevent further use of an URB
+ * @urb: pointer to URB describing a previously submitted request,
+ *	may be NULL
+ *
+ * This routine cancels an in-progress request.  It is guaranteed that
+ * upon return all completion handlers will have finished and the URB
+ * will be totally idle and cannot be reused.  These features make
+ * this an ideal way to stop I/O in a disconnect() callback.
+ * If the request has not already finished or been unlinked
+ * the completion handler will see urb->status == -ENOENT.
+ *
+ * After and while the routine runs, attempts to resubmit the URB will fail
+ * with error -EPERM.  Thus even if the URB's completion handler always
+ * tries to resubmit, it will not succeed and the URB will become idle.
+ *
+ * The URB must not be deallocated while this routine is running.  In
+ * particular, when a driver calls this routine, it must insure that the
+ * completion handler cannot deallocate the URB.
+ *
+ * This routine may not be used in an interrupt context (such as a bottom
+ * half or a completion handler), or when holding a spinlock, or in other
+ * situations where the caller can't schedule().
+ *
+ * This routine should not be called by a driver after its disconnect
+ * method has returned.
+ */
+void usb_poison_urb(struct urb *urb)
+{
+	might_sleep();
+	if (!urb)
+		return;
+	atomic_inc(&urb->reject);
+
+	if (!urb->dev || !urb->ep)
+		return;
+
+	usb_hcd_unlink_urb(urb, -ENOENT);
+	wait_event(usb_kill_urb_queue, atomic_read(&urb->use_count) == 0);
+}
+EXPORT_SYMBOL_GPL(usb_poison_urb);
+
+void usb_unpoison_urb(struct urb *urb)
+{
+	if (!urb)
+		return;
+
+	atomic_dec(&urb->reject);
+}
+EXPORT_SYMBOL_GPL(usb_unpoison_urb);
+
+/**
+ * usb_block_urb - reliably prevent further use of an URB
+ * @urb: pointer to URB to be blocked, may be NULL
+ *
+ * After the routine has run, attempts to resubmit the URB will fail
+ * with error -EPERM.  Thus even if the URB's completion handler always
+ * tries to resubmit, it will not succeed and the URB will become idle.
+ *
+ * The URB must not be deallocated while this routine is running.  In
+ * particular, when a driver calls this routine, it must insure that the
+ * completion handler cannot deallocate the URB.
+ */
+void usb_block_urb(struct urb *urb)
+{
+	if (!urb)
+		return;
+
+	atomic_inc(&urb->reject);
+}
+EXPORT_SYMBOL_GPL(usb_block_urb);
+
+/**
+ * usb_kill_anchored_urbs - cancel transfer requests en masse
+ * @anchor: anchor the requests are bound to
+ *
+ * this allows all outstanding URBs to be killed starting
+ * from the back of the queue
+ *
+ * This routine should not be called by a driver after its disconnect
+ * method has returned.
+ */
+void usb_kill_anchored_urbs(struct usb_anchor *anchor)
+{
+	struct urb *victim;
+
+	spin_lock_irq(&anchor->lock);
+	while (!list_empty(&anchor->urb_list)) {
+		victim = list_entry(anchor->urb_list.prev, struct urb,
+				    anchor_list);
+		/* we must make sure the URB isn't freed before we kill it*/
+		usb_get_urb(victim);
+		spin_unlock_irq(&anchor->lock);
+		/* this will unanchor the URB */
+		usb_kill_urb(victim);
+		usb_put_urb(victim);
+		spin_lock_irq(&anchor->lock);
+	}
+	spin_unlock_irq(&anchor->lock);
+}
+EXPORT_SYMBOL_GPL(usb_kill_anchored_urbs);
+
+
+/**
+ * usb_poison_anchored_urbs - cease all traffic from an anchor
+ * @anchor: anchor the requests are bound to
+ *
+ * this allows all outstanding URBs to be poisoned starting
+ * from the back of the queue. Newly added URBs will also be
+ * poisoned
+ *
+ * This routine should not be called by a driver after its disconnect
+ * method has returned.
+ */
+void usb_poison_anchored_urbs(struct usb_anchor *anchor)
+{
+	struct urb *victim;
+
+	spin_lock_irq(&anchor->lock);
+	anchor->poisoned = 1;
+	while (!list_empty(&anchor->urb_list)) {
+		victim = list_entry(anchor->urb_list.prev, struct urb,
+				    anchor_list);
+		/* we must make sure the URB isn't freed before we kill it*/
+		usb_get_urb(victim);
+		spin_unlock_irq(&anchor->lock);
+		/* this will unanchor the URB */
+		usb_poison_urb(victim);
+		usb_put_urb(victim);
+		spin_lock_irq(&anchor->lock);
+	}
+	spin_unlock_irq(&anchor->lock);
+}
+EXPORT_SYMBOL_GPL(usb_poison_anchored_urbs);
+
+/**
+ * usb_unpoison_anchored_urbs - let an anchor be used successfully again
+ * @anchor: anchor the requests are bound to
+ *
+ * Reverses the effect of usb_poison_anchored_urbs
+ * the anchor can be used normally after it returns
+ */
+void usb_unpoison_anchored_urbs(struct usb_anchor *anchor)
+{
+	unsigned long flags;
+	struct urb *lazarus;
+
+	spin_lock_irqsave(&anchor->lock, flags);
+	list_for_each_entry(lazarus, &anchor->urb_list, anchor_list) {
+		usb_unpoison_urb(lazarus);
+	}
+	anchor->poisoned = 0;
+	spin_unlock_irqrestore(&anchor->lock, flags);
+}
+EXPORT_SYMBOL_GPL(usb_unpoison_anchored_urbs);
+/**
+ * usb_unlink_anchored_urbs - asynchronously cancel transfer requests en masse
+ * @anchor: anchor the requests are bound to
+ *
+ * this allows all outstanding URBs to be unlinked starting
+ * from the back of the queue. This function is asynchronous.
+ * The unlinking is just triggered. It may happen after this
+ * function has returned.
+ *
+ * This routine should not be called by a driver after its disconnect
+ * method has returned.
+ */
+void usb_unlink_anchored_urbs(struct usb_anchor *anchor)
+{
+	struct urb *victim;
+
+	while ((victim = usb_get_from_anchor(anchor)) != NULL) {
+		usb_unlink_urb(victim);
+		usb_put_urb(victim);
+	}
+}
+EXPORT_SYMBOL_GPL(usb_unlink_anchored_urbs);
+
+/**
+ * usb_anchor_suspend_wakeups
+ * @anchor: the anchor you want to suspend wakeups on
+ *
+ * Call this to stop the last urb being unanchored from waking up any
+ * usb_wait_anchor_empty_timeout waiters. This is used in the hcd urb give-
+ * back path to delay waking up until after the completion handler has run.
+ */
+void usb_anchor_suspend_wakeups(struct usb_anchor *anchor)
+{
+	if (anchor)
+		atomic_inc(&anchor->suspend_wakeups);
+}
+EXPORT_SYMBOL_GPL(usb_anchor_suspend_wakeups);
+
+/**
+ * usb_anchor_resume_wakeups
+ * @anchor: the anchor you want to resume wakeups on
+ *
+ * Allow usb_wait_anchor_empty_timeout waiters to be woken up again, and
+ * wake up any current waiters if the anchor is empty.
+ */
+void usb_anchor_resume_wakeups(struct usb_anchor *anchor)
+{
+	if (!anchor)
+		return;
+
+	atomic_dec(&anchor->suspend_wakeups);
+	if (usb_anchor_check_wakeup(anchor))
+		wake_up(&anchor->wait);
+}
+EXPORT_SYMBOL_GPL(usb_anchor_resume_wakeups);
+
+/**
+ * usb_wait_anchor_empty_timeout - wait for an anchor to be unused
+ * @anchor: the anchor you want to become unused
+ * @timeout: how long you are willing to wait in milliseconds
+ *
+ * Call this is you want to be sure all an anchor's
+ * URBs have finished
+ *
+ * Return: Non-zero if the anchor became unused. Zero on timeout.
+ */
+int usb_wait_anchor_empty_timeout(struct usb_anchor *anchor,
+				  unsigned int timeout)
+{
+	return wait_event_timeout(anchor->wait,
+				  usb_anchor_check_wakeup(anchor),
+				  msecs_to_jiffies(timeout));
+}
+EXPORT_SYMBOL_GPL(usb_wait_anchor_empty_timeout);
+
+/**
+ * usb_get_from_anchor - get an anchor's oldest urb
+ * @anchor: the anchor whose urb you want
+ *
+ * This will take the oldest urb from an anchor,
+ * unanchor and return it
+ *
+ * Return: The oldest urb from @anchor, or %NULL if @anchor has no
+ * urbs associated with it.
+ */
+struct urb *usb_get_from_anchor(struct usb_anchor *anchor)
+{
+	struct urb *victim;
+	unsigned long flags;
+
+	spin_lock_irqsave(&anchor->lock, flags);
+	if (!list_empty(&anchor->urb_list)) {
+		victim = list_entry(anchor->urb_list.next, struct urb,
+				    anchor_list);
+		usb_get_urb(victim);
+		__usb_unanchor_urb(victim, anchor);
+	} else {
+		victim = NULL;
+	}
+	spin_unlock_irqrestore(&anchor->lock, flags);
+
+	return victim;
+}
+
+EXPORT_SYMBOL_GPL(usb_get_from_anchor);
+
+/**
+ * usb_scuttle_anchored_urbs - unanchor all an anchor's urbs
+ * @anchor: the anchor whose urbs you want to unanchor
+ *
+ * use this to get rid of all an anchor's urbs
+ */
+void usb_scuttle_anchored_urbs(struct usb_anchor *anchor)
+{
+	struct urb *victim;
+	unsigned long flags;
+
+	spin_lock_irqsave(&anchor->lock, flags);
+	while (!list_empty(&anchor->urb_list)) {
+		victim = list_entry(anchor->urb_list.prev, struct urb,
+				    anchor_list);
+		__usb_unanchor_urb(victim, anchor);
+	}
+	spin_unlock_irqrestore(&anchor->lock, flags);
+}
+
+EXPORT_SYMBOL_GPL(usb_scuttle_anchored_urbs);
+
+/**
+ * usb_anchor_empty - is an anchor empty
+ * @anchor: the anchor you want to query
+ *
+ * Return: 1 if the anchor has no urbs associated with it.
+ */
+int usb_anchor_empty(struct usb_anchor *anchor)
+{
+	return list_empty(&anchor->urb_list);
+}
+
+EXPORT_SYMBOL_GPL(usb_anchor_empty);
+