watchdog: pcwd_usb: Use allocated buffer for usb_control_msg

usb_control_msg() must use a dma-capable buffer.

This fixes the following error reported by smatch:

drivers/watchdog/pcwd_usb.c:257 usb_pcwd_send_command() error: doing dma on the
stack (buf)

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

diff --git a/drivers/watchdog/pcwd_usb.c b/drivers/watchdog/pcwd_usb.c
index 7b14d18..115a0eb 100644 (file)
--- a/drivers/watchdog/pcwd_usb.c
+++ b/drivers/watchdog/pcwd_usb.c
@@ -235,13 +235,17 @@ static int usb_pcwd_send_command(struct usb_pcwd_private *usb_pcwd,
                unsigned char cmd, unsigned char *msb, unsigned char *lsb)
 {
        int got_response, count;
-       unsigned char buf[6];
+       unsigned char *buf;
 
        /* We will not send any commands if the USB PCWD device does
         * not exist */
        if ((!usb_pcwd) || (!usb_pcwd->exists))
                return -1;
 
+       buf = kmalloc(6, GFP_KERNEL);
+       if (buf == NULL)
+               return 0;
+
        /* The USB PC Watchdog uses a 6 byte report format.
         * The board currently uses only 3 of the six bytes of the report. */
        buf[0] = cmd;                   /* Byte 0 = CMD */
@@ -277,6 +281,8 @@ static int usb_pcwd_send_command(struct usb_pcwd_private *usb_pcwd,
                *lsb = usb_pcwd->cmd_data_lsb;
        }
 
+       kfree(buf);
+
        return got_response;
 }