Input: uinput - allow FF requests to time out

Previously uinput force feedback requests waited for the userspace
indefinitely, which caused users to block when uinput server process
become unresponsive. Let's establish a 30 seconds deadline for servicing
upload and erase force feedback effect actions, so that users have a
chance to abort stuck requests.
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/misc/uinput.c

@@ -149,7 +149,11 @@ static int uinput_request_submit(struct uinput_device *udev,
 	if (retval)
 		goto out;
 
-	wait_for_completion(&request->done);
+	if (!wait_for_completion_timeout(&request->done, 30 * HZ)) {
+		retval = -ETIMEDOUT;
+		goto out;
+	}
+
 	retval = request->retval;
 
  out: