usb: usbtest: Convert timers to use timer_setup()

In preparation for unconditionally passing the struct timer_list pointer to
all timer callbacks, switch to using the new timer_setup() and from_timer()
to pass the timer pointer explicitly. Also adds missing call to
destroy_timer_on_stack();

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Felipe Balbi <felipe.balbi@linux.intel.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: "Gustavo A. R. Silva" <garsilva@embeddedor.com>
Cc: linux-usb@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/misc/usbtest.c

@@ -575,11 +575,16 @@ alloc_sglist(int nents, int max, int vary, struct usbtest_dev *dev, int pipe)
 	return sg;
 }
 
-static void sg_timeout(unsigned long _req)
+struct sg_timeout {
+	struct timer_list timer;
+	struct usb_sg_request *req;
+};
+
+static void sg_timeout(struct timer_list *t)
 {
-	struct usb_sg_request	*req = (struct usb_sg_request *) _req;
+	struct sg_timeout *timeout = from_timer(timeout, t, timer);
 
-	usb_sg_cancel(req);
+	usb_sg_cancel(timeout->req);
 }
 
 static int perform_sglist(
@@ -593,9 +598,11 @@ static int perform_sglist(
 {
 	struct usb_device	*udev = testdev_to_usbdev(tdev);
 	int			retval = 0;
-	struct timer_list	sg_timer;
+	struct sg_timeout	timeout = {
+		.req = req,
+	};
 
-	setup_timer_on_stack(&sg_timer, sg_timeout, (unsigned long) req);
+	timer_setup_on_stack(&timeout.timer, sg_timeout, 0);
 
 	while (retval == 0 && iterations-- > 0) {
 		retval = usb_sg_init(req, udev, pipe,
@@ -606,13 +613,14 @@ static int perform_sglist(
 
 		if (retval)
 			break;
-		mod_timer(&sg_timer, jiffies +
+		mod_timer(&timeout.timer, jiffies +
 				msecs_to_jiffies(SIMPLE_IO_TIMEOUT));
 		usb_sg_wait(req);
-		if (!del_timer_sync(&sg_timer))
+		if (!del_timer_sync(&timeout.timer))
 			retval = -ETIMEDOUT;
 		else
 			retval = req->status;
+		destroy_timer_on_stack(&timeout.timer);
 
 		/* FIXME check resulting data pattern */