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>

diff --git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c
index 499c431..ff09595 100644 (file)
--- 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.