inetpeer: Move ICMP rate limiting state into inet_peer entries.

Like metrics, the ICMP rate limiting bits are cached state about
a destination.  So move it into the inet_peer entries.

If an inet_peer cannot be bound (the reason is memory allocation
failure or similar), the policy is to allow.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/inetpeer.h b/include/net/inetpeer.h
index 61f2c66..ead2cb2 100644
--- a/include/net/inetpeer.h
+++ b/include/net/inetpeer.h
@@ -44,6 +44,8 @@
 			__u32		tcp_ts;
 			__u32		tcp_ts_stamp;
 			u32		metrics[RTAX_MAX];
+			u32		rate_tokens;	/* rate limiting for ICMP */
+			unsigned long	rate_last;
 		};
 		struct rcu_head         rcu;
 	};
@@ -81,6 +83,7 @@
 
 /* can be called from BH context or outside */
 extern void inet_putpeer(struct inet_peer *p);
+extern bool inet_peer_xrlim_allow(struct inet_peer *peer, int timeout);
 
 /*
  * temporary check to make sure we dont access rid, ip_id_count, tcp_ts,