USB: musb_host, minor enqueue locking fix (v2)

Someone noted that the enqueue path used an unlocked access
for usb_host_endpoint->hcpriv ... fix that, by being safe
and always accessing it under spinlock protection.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 8 insertions, 9 deletions

diff --git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c
index 499c431a6d62..ff095956ca96 100644
--- a/drivers/usb/musb/musb_host.c
+++ b/drivers/usb/musb/musb_host.c
@@ -1841,7 +1841,7 @@ static int musb_urb_enqueue(
         unsigned long                   flags;
         struct musb                     *musb = hcd_to_musb(hcd);
         struct usb_host_endpoint        *hep = urb->ep;
-        struct musb_qh                  *qh = hep->hcpriv;
+        struct musb_qh                  *qh;
         struct usb_endpoint_descriptor  *epd = &hep->desc;
         int                             ret;
         unsigned                        type_reg;
@@ -1853,22 +1853,21 @@ static int musb_urb_enqueue(
 
         spin_lock_irqsave(&musb->lock, flags);
         ret = usb_hcd_link_urb_to_ep(hcd, urb);
+        qh = ret ? NULL : hep->hcpriv;
+        if (qh)
+                urb->hcpriv = qh;
         spin_unlock_irqrestore(&musb->lock, flags);
-        if (ret)
-                return ret;
 
         /* DMA mapping was already done, if needed, and this urb is on
-         * hep->urb_list ... so there's little to do unless hep wasn't
-         * yet scheduled onto a live qh.
+         * hep->urb_list now ... so we're done, unless hep wasn't yet
+         * scheduled onto a live qh.
          *
          * REVISIT best to keep hep->hcpriv valid until the endpoint gets
          * disabled, testing for empty qh->ring and avoiding qh setup costs
          * except for the first urb queued after a config change.
          */
-        if (qh) {
-                urb->hcpriv = qh;
-                return 0;
-        }
+        if (qh || ret)
+                return ret;
 
         /* Allocate and initialize qh, minimizing the work done each time
          * hw_ep gets reprogrammed, or with irqs blocked.  Then schedule it.