[PATCH] drivers/usb/host/imx21-hcd.c: fix divide-by-zero in func nonisoc_etd_done

[Duyanlin]

If the function usb_maxpacket(urb->dev, urb->pipe, usb_pipeout(urb->pipe)) 
returns 0, that will cause a illegal divide-by-zero operation, unexpected 
results may occur.
It is best to ensure that the denominator is non-zero before dividing by zero.

Signed-off-by: Yanlin Du <duyan...@huawei.com>
---
 drivers/usb/host/imx21-hcd.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/host/imx21-hcd.c b/drivers/usb/host/imx21-hcd.c index 
6e3dad1..6a47f78 100644
--- a/drivers/usb/host/imx21-hcd.c
+++ b/drivers/usb/host/imx21-hcd.c
@@ -1038,6 +1038,7 @@ static void nonisoc_etd_done(struct usb_hcd *hcd, int 
etd_num)
        int cc;
        u32 bytes_xfrd;
        int etd_done;
+       unsigned int maxp;
 
        disactivate_etd(imx21, etd_num);
 
@@ -1104,13 +1105,13 @@ static void nonisoc_etd_done(struct usb_hcd *hcd, int 
etd_num)
                break;
 
        case PIPE_BULK:
+               maxp = usb_maxpacket(urb->dev, urb->pipe,
+                               usb_pipeout(urb->pipe));
                urb->actual_length += bytes_xfrd;
                if ((urb_priv->state == US_BULK)
                    && (urb->transfer_flags & URB_ZERO_PACKET)
                    && urb->transfer_buffer_length > 0
-                   && ((urb->transfer_buffer_length %
-                        usb_maxpacket(urb->dev, urb->pipe,
-                                      usb_pipeout(urb->pipe))) == 0)) {
+                   && maxp && (urb->transfer_buffer_length % maxp == 0)) {
                        /* need a 0-packet */
                        urb_priv->state = US_BULK0;
                } else {
--
1.8.5.6