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path: root/drivers/usb/core/hcd.c
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Diffstat (limited to 'drivers/usb/core/hcd.c')
-rw-r--r--drivers/usb/core/hcd.c35
1 files changed, 32 insertions, 3 deletions
diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index fc9018e..e1b4262 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -106,6 +106,9 @@ static DEFINE_SPINLOCK(hcd_root_hub_lock);
/* used when updating an endpoint's URB list */
static DEFINE_SPINLOCK(hcd_urb_list_lock);
+/* used to protect against unlinking URBs after the device is gone */
+static DEFINE_SPINLOCK(hcd_urb_unlink_lock);
+
/* wait queue for synchronous unlinks */
DECLARE_WAIT_QUEUE_HEAD(usb_kill_urb_queue);
@@ -1376,10 +1379,25 @@ static int unlink1(struct usb_hcd *hcd, struct urb *urb, int status)
int usb_hcd_unlink_urb (struct urb *urb, int status)
{
struct usb_hcd *hcd;
- int retval;
+ int retval = -EIDRM;
+ unsigned long flags;
- hcd = bus_to_hcd(urb->dev->bus);
- retval = unlink1(hcd, urb, status);
+ /* Prevent the device and bus from going away while
+ * the unlink is carried out. If they are already gone
+ * then urb->use_count must be 0, since disconnected
+ * devices can't have any active URBs.
+ */
+ spin_lock_irqsave(&hcd_urb_unlink_lock, flags);
+ if (atomic_read(&urb->use_count) > 0) {
+ retval = 0;
+ usb_get_dev(urb->dev);
+ }
+ spin_unlock_irqrestore(&hcd_urb_unlink_lock, flags);
+ if (retval == 0) {
+ hcd = bus_to_hcd(urb->dev->bus);
+ retval = unlink1(hcd, urb, status);
+ usb_put_dev(urb->dev);
+ }
if (retval == 0)
retval = -EINPROGRESS;
@@ -1528,6 +1546,17 @@ void usb_hcd_disable_endpoint(struct usb_device *udev,
hcd->driver->endpoint_disable(hcd, ep);
}
+/* Protect against drivers that try to unlink URBs after the device
+ * is gone, by waiting until all unlinks for @udev are finished.
+ * Since we don't currently track URBs by device, simply wait until
+ * nothing is running in the locked region of usb_hcd_unlink_urb().
+ */
+void usb_hcd_synchronize_unlinks(struct usb_device *udev)
+{
+ spin_lock_irq(&hcd_urb_unlink_lock);
+ spin_unlock_irq(&hcd_urb_unlink_lock);
+}
+
/*-------------------------------------------------------------------------*/
/* called in any context */