[PATCH] usb: host: xhci-dbgtty: fix check in dbc_tty_write()

[PATCH] usb: host: xhci-dbgtty: fix check in dbc_tty_write()

[Sergey Shtylyov]

The 'int count' parameter of the tty write() method gets assigned to
*unsigned long* local variable in the fifo_in() macro which implies
a problematic type cast.  Fix the 'count' check before the fifo_in()
invocation to account for the signed type of the 'count' parameter...

Found by Linux Verification Center (linuxtesting.org) with the SVACE static
analysis tool.

Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>

---
 drivers/usb/host/xhci-dbgtty.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: usb/drivers/usb/host/xhci-dbgtty.c
===================================================================
--- usb.orig/drivers/usb/host/xhci-dbgtty.c
+++ usb/drivers/usb/host/xhci-dbgtty.c
@@ -216,7 +216,7 @@ static int dbc_tty_write(struct tty_stru
 	unsigned long		flags;
 
 	spin_lock_irqsave(&port->port_lock, flags);
-	if (count)
+	if (count > 0)
 		count = kfifo_in(&port->write_fifo, buf, count);
 	dbc_start_tx(port);
 	spin_unlock_irqrestore(&port->port_lock, flags);