staging: usbip: bugfix for deadlock

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>

diff --git a/drivers/staging/usbip/vhci_rx.c b/drivers/staging/usbip/vhci_rx.c
index e42ce9dab7ac5cf15676b7ac935a0fa21dea5431..5c4b5d94450818ef5daf540ee7d785eb2d70de1d 100644 (file)
--- 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);