There is no need to get an interface specification if we know it's the
wrong one; trivial change. The big thing, though, was explained in the
#mipslinux IRC channel: 
[Mon 2013-08-19 12:28:21 PM PDT] <headless> guys, are you sure it's not "DMA 
off stack" case?
[Mon 2013-08-19 12:28:35 PM PDT] <headless> it's a known stack corruptor on 
non-coherent arches
[Mon 2013-08-19 12:31:48 PM PDT] <DonkeyHotei> headless: for usb/ehci?
[Mon 2013-08-19 12:34:11 PM PDT] <DonkeyHotei> headless: explain
[Mon 2013-08-19 12:35:38 PM PDT] <headless> usb_control_msg() (or other such 
func) should not use buffer on stack. DMA from/to stack is prohibited
[Mon 2013-08-19 12:35:58 PM PDT] <headless> and EHCI uses DMA on control xfers 
(as well as all the others)

Signed-off-by: Daniel Gimpelevich <dan...@gimpelevich.san-francisco.ca.us>
---
 drivers/net/usb/hso.c |   15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/net/usb/hso.c b/drivers/net/usb/hso.c
index cba1d46..86292e6 100644
--- a/drivers/net/usb/hso.c
+++ b/drivers/net/usb/hso.c
@@ -2816,13 +2816,16 @@ exit:
 static int hso_get_config_data(struct usb_interface *interface)
 {
        struct usb_device *usbdev = interface_to_usbdev(interface);
-       u8 config_data[17];
+       u8 *config_data = kmalloc(17, GFP_KERNEL);
        u32 if_num = interface->altsetting->desc.bInterfaceNumber;
        s32 result;
 
+       if (!config_data)
+               return -ENOMEM;
        if (usb_control_msg(usbdev, usb_rcvctrlpipe(usbdev, 0),
                            0x86, 0xC0, 0, 0, config_data, 17,
                            USB_CTRL_SET_TIMEOUT) != 0x11) {
+               kfree(config_data);
                return -EIO;
        }
 
@@ -2873,6 +2876,7 @@ static int hso_get_config_data(struct usb_interface 
*interface)
        if (config_data[16] & 0x1)
                result |= HSO_INFO_CRC_BUG;
 
+       kfree(config_data);
        return result;
 }
 
@@ -2886,6 +2890,11 @@ static int hso_probe(struct usb_interface *interface,
        struct hso_shared_int *shared_int;
        struct hso_device *tmp_dev = NULL;
 
+       if (interface->cur_altsetting->desc.bInterfaceClass != 0xFF) {
+               dev_err(&interface->dev, "Not our interface\n");
+               return -ENODEV;
+       }
+
        if_num = interface->altsetting->desc.bInterfaceNumber;
 
        /* Get the interface/port specification from either driver_info or from
@@ -2895,10 +2904,6 @@ static int hso_probe(struct usb_interface *interface,
        else
                port_spec = hso_get_config_data(interface);
 
-       if (interface->cur_altsetting->desc.bInterfaceClass != 0xFF) {
-               dev_err(&interface->dev, "Not our interface\n");
-               return -ENODEV;
-       }
        /* Check if we need to switch to alt interfaces prior to port
         * configuration */
        if (interface->num_altsetting > 1)
-- 
1.7.9.5

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