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path: root/drivers/usb/core/urb.c
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Diffstat (limited to 'drivers/usb/core/urb.c')
-rw-r--r--drivers/usb/core/urb.c346
1 files changed, 228 insertions, 118 deletions
diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c
index 16927fa88fbd..ff8df16cca35 100644
--- a/drivers/usb/core/urb.c
+++ b/drivers/usb/core/urb.c
@@ -1,12 +1,18 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Released under the GPLv2 only.
+ */
+
#include <linux/module.h>
#include <linux/string.h>
#include <linux/bitops.h>
#include <linux/slab.h>
-#include <linux/init.h>
#include <linux/log2.h>
+#include <linux/kmsan.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)
@@ -40,6 +46,7 @@ void usb_init_urb(struct urb *urb)
if (urb) {
memset(urb, 0, sizeof(*urb));
kref_init(&urb->kref);
+ INIT_LIST_HEAD(&urb->urb_list);
INIT_LIST_HEAD(&urb->anchor_list);
}
}
@@ -52,26 +59,23 @@ EXPORT_SYMBOL_GPL(usb_init_urb);
* valid options for this.
*
* Creates an urb for the USB driver to use, initializes a few internal
- * structures, incrementes the usage counter, and returns a pointer to it.
- *
- * If no memory is available, NULL is returned.
+ * 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");
+ urb = kmalloc(struct_size(urb, iso_frame_desc, iso_packets),
+ mem_flags);
+ if (!urb)
return NULL;
- }
usb_init_urb(urb);
return urb;
}
@@ -102,7 +106,7 @@ EXPORT_SYMBOL_GPL(usb_free_urb);
* host controller driver. This allows proper reference counting to happen
* for urbs.
*
- * A pointer to the urb with the incremented reference counter is returned.
+ * Return: A pointer to the urb with the incremented reference counter.
*/
struct urb *usb_get_urb(struct urb *urb)
{
@@ -129,21 +133,26 @@ void usb_anchor_urb(struct urb *urb, struct usb_anchor *anchor)
list_add_tail(&urb->anchor_list, &anchor->urb_list);
urb->anchor = anchor;
- if (unlikely(anchor->poisoned)) {
+ 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 (list_empty(&anchor->urb_list))
+ if (usb_anchor_check_wakeup(anchor))
wake_up(&anchor->wait);
}
@@ -179,6 +188,46 @@ EXPORT_SYMBOL_GPL(usb_unanchor_urb);
/*-------------------------------------------------------------------*/
+static const int pipetypes[4] = {
+ PIPE_CONTROL, PIPE_ISOCHRONOUS, PIPE_BULK, PIPE_INTERRUPT
+};
+
+/**
+ * usb_pipe_type_check - sanity check of a specific pipe for a usb device
+ * @dev: struct usb_device to be checked
+ * @pipe: pipe to check
+ *
+ * This performs a light-weight sanity check for the endpoint in the
+ * given usb device. It returns 0 if the pipe is valid for the specific usb
+ * device, otherwise a negative error code.
+ */
+int usb_pipe_type_check(struct usb_device *dev, unsigned int pipe)
+{
+ const struct usb_host_endpoint *ep;
+
+ ep = usb_pipe_endpoint(dev, pipe);
+ if (!ep)
+ return -EINVAL;
+ if (usb_pipetype(pipe) != pipetypes[usb_endpoint_type(&ep->desc)])
+ return -EINVAL;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(usb_pipe_type_check);
+
+/**
+ * usb_urb_ep_type_check - sanity check of endpoint in the given urb
+ * @urb: urb to be checked
+ *
+ * This performs a light-weight sanity check for the endpoint in the
+ * given urb. It returns 0 if the urb contains a valid endpoint, otherwise
+ * a negative error code.
+ */
+int usb_urb_ep_type_check(const struct urb *urb)
+{
+ return usb_pipe_type_check(urb->dev, urb->pipe);
+}
+EXPORT_SYMBOL_GPL(usb_urb_ep_type_check);
+
/**
* usb_submit_urb - issue an asynchronous transfer request for an endpoint
* @urb: pointer to the urb describing the request
@@ -199,13 +248,12 @@ EXPORT_SYMBOL_GPL(usb_unanchor_urb);
* the particular kind of transfer, although they will not initialize
* any transfer flags.
*
- * Successful submissions return 0; otherwise this routine returns a
- * negative error number. 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.
+ * 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.
@@ -240,6 +288,9 @@ EXPORT_SYMBOL_GPL(usb_unanchor_urb);
* 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
@@ -272,7 +323,7 @@ EXPORT_SYMBOL_GPL(usb_unanchor_urb);
*
* 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 callacks). When there is no longer an urb
+ * 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
@@ -320,6 +371,8 @@ int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
struct usb_device *dev;
struct usb_host_endpoint *ep;
int is_out;
+ unsigned int allowed;
+ bool is_eusb2_isoch_double;
if (!urb || !urb->complete)
return -EINVAL;
@@ -356,6 +409,15 @@ int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
return -ENOEXEC;
is_out = !(setup->bRequestType & USB_DIR_IN) ||
!setup->wLength;
+ dev_WARN_ONCE(&dev->dev, (usb_pipeout(urb->pipe) != is_out),
+ "BOGUS control dir, pipe %x doesn't match bRequestType %x\n",
+ urb->pipe, setup->bRequestType);
+ if (le16_to_cpu(setup->wLength) != urb->transfer_buffer_length) {
+ dev_dbg(&dev->dev, "BOGUS control len %d doesn't match transfer length %d\n",
+ le16_to_cpu(setup->wLength),
+ urb->transfer_buffer_length);
+ return -EBADR;
+ }
} else {
is_out = usb_endpoint_dir_out(&ep->desc);
}
@@ -366,13 +428,15 @@ int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
URB_SETUP_MAP_SINGLE | URB_SETUP_MAP_LOCAL |
URB_DMA_SG_COMBINED);
urb->transfer_flags |= (is_out ? URB_DIR_OUT : URB_DIR_IN);
+ kmsan_handle_urb(urb, is_out);
if (xfertype != USB_ENDPOINT_XFER_CONTROL &&
dev->state < USB_STATE_CONFIGURED)
return -ENODEV;
max = usb_endpoint_maxp(&ep->desc);
- if (max <= 0) {
+ is_eusb2_isoch_double = usb_endpoint_is_hs_isoc_double(dev, ep);
+ if (!max && !is_eusb2_isoch_double) {
dev_dbg(&dev->dev,
"bogus endpoint ep%d%s in %s (bad maxpacket %d)\n",
usb_endpoint_num(&ep->desc), is_out ? "out" : "in",
@@ -390,18 +454,27 @@ int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
/* SuperSpeed isoc endpoints have up to 16 bursts of up to
* 3 packets each
*/
- if (dev->speed == USB_SPEED_SUPER) {
+ 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_SUPER_PLUS &&
+ USB_SS_SSP_ISOC_COMP(ep->ss_ep_comp.bmAttributes)) {
+ struct usb_ssp_isoc_ep_comp_descriptor *isoc_ep_comp;
+
+ isoc_ep_comp = &ep->ssp_isoc_ep_comp;
+ max = le32_to_cpu(isoc_ep_comp->dwBytesPerInterval);
+ }
+
+ /* High speed, 1-3 packets/uframe, max 6 for eUSB2 double bw */
if (dev->speed == USB_SPEED_HIGH) {
- int mult = 1 + ((max >> 11) & 0x03);
- max &= 0x07ff;
- max *= mult;
+ if (is_eusb2_isoch_double)
+ max = le32_to_cpu(ep->eusb2_isoc_ep_comp.dwBytesPerInterval);
+ else
+ max *= usb_endpoint_maxp_mult(&ep->desc);
}
if (urb->number_of_packets <= 0)
@@ -413,25 +486,27 @@ int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
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) {
+ 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;
-#ifdef DEBUG
- /* stuff that drivers shouldn't do, but which shouldn't
+ /*
+ * stuff that drivers shouldn't do, but which shouldn't
* cause problems in HCDs if they get it wrong.
*/
- {
- unsigned int allowed;
- static int pipetypes[4] = {
- PIPE_CONTROL, PIPE_ISOCHRONOUS, PIPE_BULK, PIPE_INTERRUPT
- };
/* 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",
+ if (usb_pipe_type_check(urb->dev, urb->pipe))
+ dev_warn_once(&dev->dev, "BOGUS urb xfer, pipe %x != type %x\n",
usb_pipetype(urb->pipe), pipetypes[xfertype]);
/* Check against a simple/standard policy */
@@ -439,12 +514,10 @@ int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
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 */
+ fallthrough;
default: /* all non-iso endpoints */
if (!is_out)
allowed |= URB_SHORT_NOT_OK;
@@ -459,8 +532,7 @@ int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
if (allowed != urb->transfer_flags)
dev_WARN(&dev->dev, "BOGUS urb flags, %x --> %x\n",
urb->transfer_flags, allowed);
- }
-#endif
+
/*
* Force periodic transfer intervals to be legal values that are
* a power of two (so HCDs don't need to).
@@ -473,28 +545,18 @@ int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
case USB_ENDPOINT_XFER_ISOC:
case USB_ENDPOINT_XFER_INT:
/* too small? */
- switch (dev->speed) {
- case USB_SPEED_WIRELESS:
- if (urb->interval < 6)
- return -EINVAL;
- break;
- default:
- if (urb->interval <= 0)
- return -EINVAL;
- break;
- }
+ if (urb->interval <= 0)
+ return -EINVAL;
+
/* too big? */
switch (dev->speed) {
+ case USB_SPEED_SUPER_PLUS:
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))
@@ -518,10 +580,8 @@ int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
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));
- }
+ /* 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);
@@ -543,10 +603,9 @@ EXPORT_SYMBOL_GPL(usb_submit_urb);
* 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.
+ * usb_kill_urb(), 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
@@ -564,6 +623,9 @@ EXPORT_SYMBOL_GPL(usb_submit_urb);
* 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
@@ -645,6 +707,12 @@ void usb_kill_urb(struct urb *urb)
if (!(urb && urb->dev && urb->ep))
return;
atomic_inc(&urb->reject);
+ /*
+ * Order the write of urb->reject above before the read
+ * of urb->use_count below. Pairs with the barriers in
+ * __usb_hcd_giveback_urb() and usb_hcd_submit_urb().
+ */
+ smp_mb__after_atomic();
usb_hcd_unlink_urb(urb, -ENOENT);
wait_event(usb_kill_urb_queue, atomic_read(&urb->use_count) == 0);
@@ -686,6 +754,12 @@ void usb_poison_urb(struct urb *urb)
if (!urb)
return;
atomic_inc(&urb->reject);
+ /*
+ * Order the write of urb->reject above before the read
+ * of urb->use_count below. Pairs with the barriers in
+ * __usb_hcd_giveback_urb() and usb_hcd_submit_urb().
+ */
+ smp_mb__after_atomic();
if (!urb->dev || !urb->ep)
return;
@@ -726,11 +800,12 @@ void usb_block_urb(struct urb *urb)
EXPORT_SYMBOL_GPL(usb_block_urb);
/**
- * usb_kill_anchored_urbs - cancel transfer requests en masse
+ * usb_kill_anchored_urbs - kill all URBs associated with an anchor
* @anchor: anchor the requests are bound to
*
- * this allows all outstanding URBs to be killed starting
- * from the back of the queue
+ * This kills all outstanding URBs starting from the back of the queue,
+ * with guarantee that no completer callbacks will take place from the
+ * anchor after this function returns.
*
* This routine should not be called by a driver after its disconnect
* method has returned.
@@ -738,20 +813,26 @@ EXPORT_SYMBOL_GPL(usb_block_urb);
void usb_kill_anchored_urbs(struct usb_anchor *anchor)
{
struct urb *victim;
+ int surely_empty;
- 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);
+ do {
spin_lock_irq(&anchor->lock);
- }
- spin_unlock_irq(&anchor->lock);
+ while (!list_empty(&anchor->urb_list)) {
+ victim = list_entry(anchor->urb_list.prev,
+ struct urb, anchor_list);
+ /* 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);
+ }
+ surely_empty = usb_anchor_check_wakeup(anchor);
+
+ spin_unlock_irq(&anchor->lock);
+ cpu_relax();
+ } while (!surely_empty);
}
EXPORT_SYMBOL_GPL(usb_kill_anchored_urbs);
@@ -770,21 +851,27 @@ EXPORT_SYMBOL_GPL(usb_kill_anchored_urbs);
void usb_poison_anchored_urbs(struct usb_anchor *anchor)
{
struct urb *victim;
+ int surely_empty;
- 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);
+ do {
spin_lock_irq(&anchor->lock);
- }
- spin_unlock_irq(&anchor->lock);
+ anchor->poisoned = 1;
+ while (!list_empty(&anchor->urb_list)) {
+ victim = list_entry(anchor->urb_list.prev,
+ struct urb, anchor_list);
+ /* 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);
+ }
+ surely_empty = usb_anchor_check_wakeup(anchor);
+
+ spin_unlock_irq(&anchor->lock);
+ cpu_relax();
+ } while (!surely_empty);
}
EXPORT_SYMBOL_GPL(usb_poison_anchored_urbs);
@@ -808,28 +895,39 @@ void usb_unpoison_anchored_urbs(struct usb_anchor *anchor)
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
+ * usb_anchor_suspend_wakeups
+ * @anchor: the anchor you want to suspend wakeups on
*
- * this allows all outstanding URBs to be unlinked starting
- * from the back of the queue. This function is asynchronous.
- * The unlinking is just tiggered. It may happen after this
- * function has returned.
+ * 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
*
- * This routine should not be called by a driver after its disconnect
- * method has returned.
+ * 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_unlink_anchored_urbs(struct usb_anchor *anchor)
+void usb_anchor_resume_wakeups(struct usb_anchor *anchor)
{
- struct urb *victim;
+ if (!anchor)
+ return;
- while ((victim = usb_get_from_anchor(anchor)) != NULL) {
- usb_unlink_urb(victim);
- usb_put_urb(victim);
- }
+ atomic_dec(&anchor->suspend_wakeups);
+ if (usb_anchor_check_wakeup(anchor))
+ wake_up(&anchor->wait);
}
-EXPORT_SYMBOL_GPL(usb_unlink_anchored_urbs);
+EXPORT_SYMBOL_GPL(usb_anchor_resume_wakeups);
/**
* usb_wait_anchor_empty_timeout - wait for an anchor to be unused
@@ -838,11 +936,14 @@ EXPORT_SYMBOL_GPL(usb_unlink_anchored_urbs);
*
* 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, list_empty(&anchor->urb_list),
+ return wait_event_timeout(anchor->wait,
+ usb_anchor_check_wakeup(anchor),
msecs_to_jiffies(timeout));
}
EXPORT_SYMBOL_GPL(usb_wait_anchor_empty_timeout);
@@ -851,8 +952,11 @@ 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,
+ * 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)
{
@@ -885,14 +989,20 @@ void usb_scuttle_anchored_urbs(struct usb_anchor *anchor)
{
struct urb *victim;
unsigned long flags;
+ int surely_empty;
+
+ do {
+ 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);
+ }
+ surely_empty = usb_anchor_check_wakeup(anchor);
- 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);
+ spin_unlock_irqrestore(&anchor->lock, flags);
+ cpu_relax();
+ } while (!surely_empty);
}
EXPORT_SYMBOL_GPL(usb_scuttle_anchored_urbs);
@@ -901,7 +1011,7 @@ EXPORT_SYMBOL_GPL(usb_scuttle_anchored_urbs);
* usb_anchor_empty - is an anchor empty
* @anchor: the anchor you want to query
*
- * returns 1 if the anchor has no urbs associated with it
+ * Return: 1 if the anchor has no urbs associated with it.
*/
int usb_anchor_empty(struct usb_anchor *anchor)
{