diff options
Diffstat (limited to 'drivers/usb/core/hcd.c')
| -rw-r--r-- | drivers/usb/core/hcd.c | 35 |
1 files changed, 32 insertions, 3 deletions
diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c index fc9018e72a09..e1b42626d04d 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 */ |