staging: usbip: bugfix for deadlock

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>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 6 insertions, 4 deletions

diff --git a/drivers/staging/usbip/vhci_rx.c b/drivers/staging/usbip/vhci_rx.c
index 09c44abb89e8..3872b8cccdcf 100644
--- a/drivers/staging/usbip/vhci_rx.c
+++ b/drivers/staging/usbip/vhci_rx.c
@@ -68,6 +68,7 @@ static void vhci_recv_ret_submit(struct vhci_device *vdev,
 {
         struct usbip_device *ud = &vdev->ud;
         struct urb *urb;
+        unsigned long flags;
 
         spin_lock(&vdev->priv_lock);
         urb = pickup_urb_and_free_priv(vdev, pdu->base.seqnum);
@@ -101,9 +102,9 @@ static void vhci_recv_ret_submit(struct vhci_device *vdev,
 
         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);
 
@@ -141,6 +142,7 @@ static void vhci_recv_ret_unlink(struct vhci_device *vdev,
 {
         struct vhci_unlink *unlink;
         struct urb *urb;
+        unsigned long flags;
 
         usbip_dump_header(pdu);
 
@@ -170,9 +172,9 @@ static void vhci_recv_ret_unlink(struct vhci_device *vdev,
                 urb->status = pdu->u.ret_unlink.status;
                 pr_info("urb->status %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);