commit 2656a9abcf1ec8dd5fee6a75d6997a0f2fa0094e
Author: Alan Stern <stern@rowland.harvard.edu>
Date:   Thu Nov 8 10:17:01 2012 -0500

    USB: EHCI: bugfix: urb->hcpriv should not be NULL
    
    This patch (as1632b) fixes a bug in ehci-hcd.  The USB core uses
    urb->hcpriv to determine whether or not an URB is active; host
    controller drivers are supposed to set this pointer to a non-NULL
    value when an URB is queued.  However ehci-hcd sets it to NULL for
    isochronous URBs, which defeats the check in usbcore.
    
    In itself this isn't a big deal.  But people have recently found that
    certain sequences of actions will cause the snd-usb-audio driver to
    reuse URBs without waiting for them to complete.  In the absence of
    proper checking by usbcore, the URBs get added to their endpoint list
    twice.  This leads to list corruption and a system freeze.
    
    The patch makes ehci-hcd assign a meaningful value to urb->hcpriv for
    isochronous URBs.  Improving robustness always helps.
    
    Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
    Reported-by: Artem S. Tashkinov <t.artem@lycos.com>
    Reported-by: Christof Meerwald <cmeerw@cmeerw.org>
    CC: <stable@vger.kernel.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/host/ehci-q.c b/drivers/usb/host/ehci-q.c
index 4b66374..3d98902 100644
--- a/drivers/usb/host/ehci-q.c
+++ b/drivers/usb/host/ehci-q.c
@@ -264,15 +264,9 @@ ehci_urb_done(struct ehci_hcd *ehci, struct urb *urb, int status)
 __releases(ehci->lock)
 __acquires(ehci->lock)
 {
-	if (likely (urb->hcpriv != NULL)) {
-		struct ehci_qh	*qh = (struct ehci_qh *) urb->hcpriv;
-
-		/* S-mask in a QH means it's an interrupt urb */
-		if ((qh->hw->hw_info2 & cpu_to_hc32(ehci, QH_SMASK)) != 0) {
-
-			/* ... update hc-wide periodic stats (for usbfs) */
-			ehci_to_hcd(ehci)->self.bandwidth_int_reqs--;
-		}
+	if (usb_pipetype(urb->pipe) == PIPE_INTERRUPT) {
+		/* ... update hc-wide periodic stats */
+		ehci_to_hcd(ehci)->self.bandwidth_int_reqs--;
 	}

 	if (unlikely(urb->unlinked)) {
diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index 2e14714..69ebee7 100644
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -1630,7 +1630,7 @@ static void itd_link_urb(

 	/* don't need that schedule data any more */
 	iso_sched_free (stream, iso_sched);
-	urb->hcpriv = NULL;
+	urb->hcpriv = stream;

 	++ehci->isoc_count;
 	enable_periodic(ehci);
@@ -2029,7 +2029,7 @@ static void sitd_link_urb(

 	/* don't need that schedule data any more */
 	iso_sched_free (stream, sched);
-	urb->hcpriv = NULL;
+	urb->hcpriv = stream;

 	++ehci->isoc_count;
 	enable_periodic(ehci);