net: ingress filter message limit

If user misconfigures ingress and causes a redirection loop, don't
overwhelm the log. This is also a error case so make it unlikely.
Found by inspection, luckily not in real system.

Signed-off-by: Stephen Hemminger <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/core/dev.c

···
 	int result = TC_ACT_OK;
 	struct Qdisc *q;
 
-	if (MAX_RED_LOOP < ttl++) {
-		printk(KERN_WARNING
-		       "Redir loop detected Dropping packet (%d->%d)\n",
-		       skb->skb_iif, dev->ifindex);
+	if (unlikely(MAX_RED_LOOP < ttl++)) {
+		if (net_ratelimit())
+			pr_warning( "Redir loop detected Dropping packet (%d->%d)\n",
+			       skb->skb_iif, dev->ifindex);
 		return TC_ACT_SHOT;
 	}