[12/27] staging: usbip: bugfix for deadlock

[Greg KH <gregkh@suse.de>]

2.6.32-longterm review patch.  If anyone has any objections, please let me know.

------------------

From: Bart Westgeest <bart@elbrys.com>

commit 438957f8d4a84daa7fa5be6978ad5897a2e9e5e5 upstream.

Interrupts must be disabled prior to calling usb_hcd_unlink_urb_from_ep.
If interrupts are not disabled, it can potentially lead to a deadlock.
The deadlock is readily reproduceable on a slower (ARM based) device
such as the TI Pandaboard.

Signed-off-by: Bart Westgeest <bart@elbrys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 drivers/staging/usbip/vhci_rx.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

--- a/drivers/staging/usbip/vhci_rx.c
+++ b/drivers/staging/usbip/vhci_rx.c
@@ -67,6 +67,7 @@ static void vhci_recv_ret_submit(struct
 {
 	struct usbip_device *ud = &vdev->ud;
 	struct urb *urb;
+	unsigned long flags;
 
 	spin_lock(&vdev->priv_lock);
 
@@ -107,9 +108,9 @@ static void vhci_recv_ret_submit(struct
 
 	usbip_dbg_vhci_rx("now giveback urb %p\n", urb);
 
-	spin_lock(&the_controller->lock);
+	spin_lock_irqsave(&the_controller->lock, flags);
 	usb_hcd_unlink_urb_from_ep(vhci_to_hcd(the_controller), urb);
-	spin_unlock(&the_controller->lock);
+	spin_unlock_irqrestore(&the_controller->lock, flags);
 
 	usb_hcd_giveback_urb(vhci_to_hcd(the_controller), urb, urb->status);
 
@@ -150,6 +151,7 @@ static void vhci_recv_ret_unlink(struct
 {
 	struct vhci_unlink *unlink;
 	struct urb *urb;
+	unsigned long flags;
 
 	usbip_dump_header(pdu);
 
@@ -181,9 +183,9 @@ static void vhci_recv_ret_unlink(struct
 		urb->status = pdu->u.ret_unlink.status;
 		usbip_uinfo("%d\n", urb->status);
 
-		spin_lock(&the_controller->lock);
+		spin_lock_irqsave(&the_controller->lock, flags);
 		usb_hcd_unlink_urb_from_ep(vhci_to_hcd(the_controller), urb);
-		spin_unlock(&the_controller->lock);
+		spin_unlock_irqrestore(&the_controller->lock, flags);
 
 		usb_hcd_giveback_urb(vhci_to_hcd(the_controller), urb,
 								urb->status);