netfilter: xt_LED: fix too short led-always-blink

If led-always-blink is set, then between switch led OFF and ON
is almost zero time. So blink is invisible. This use oneshot led trigger
with fixed time 50ms witch is enough to see blink.
Signed-off-by: Jiri Prchal <jiri.prchal@aksignal.cz>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/xt_LED.c

@@ -50,11 +50,14 @@ struct xt_led_info_internal {
 	struct timer_list timer;
 };
 
+#define XT_LED_BLINK_DELAY 50 /* ms */
+
 static unsigned int
 led_tg(struct sk_buff *skb, const struct xt_action_param *par)
 {
 	const struct xt_led_info *ledinfo = par->targinfo;
 	struct xt_led_info_internal *ledinternal = ledinfo->internal_data;
+	unsigned long led_delay = XT_LED_BLINK_DELAY;
 
 	/*
 	 * If "always blink" is enabled, and there's still some time until the
@@ -62,9 +65,10 @@ led_tg(struct sk_buff *skb, const struct xt_action_param *par)
 	 */
 	if ((ledinfo->delay > 0) && ledinfo->always_blink &&
 	    timer_pending(&ledinternal->timer))
-		led_trigger_event(&ledinternal->netfilter_led_trigger, LED_OFF);
-
-	led_trigger_event(&ledinternal->netfilter_led_trigger, LED_FULL);
+		led_trigger_blink_oneshot(&ledinternal->netfilter_led_trigger,
+					  &led_delay, &led_delay, 1);
+	else
+		led_trigger_event(&ledinternal->netfilter_led_trigger, LED_FULL);
 
 	/* If there's a positive delay, start/update the timer */
 	if (ledinfo->delay > 0) {