inet: Sanitize inet{,6} protocol demux.

Don't pretend that inet_protos[] and inet6_protos[] are hashes, thay
are just a straight arrays.  Remove all unnecessary hash masking.

Document MAX_INET_PROTOS.

Use RAW_HTABLE_SIZE when appropriate.

Reported-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index e1caa1a..49a74cc 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -637,12 +637,12 @@
 
 static void icmp_unreach(struct sk_buff *skb)
 {
+	const struct net_protocol *ipprot;
 	const struct iphdr *iph;
 	struct icmphdr *icmph;
-	int hash, protocol;
-	const struct net_protocol *ipprot;
-	u32 info = 0;
 	struct net *net;
+	u32 info = 0;
+	int protocol;
 
 	net = dev_net(skb_dst(skb)->dev);
 
@@ -731,9 +731,8 @@
 	 */
 	raw_icmp_error(skb, protocol, info);
 
-	hash = protocol & (MAX_INET_PROTOS - 1);
 	rcu_read_lock();
-	ipprot = rcu_dereference(inet_protos[hash]);
+	ipprot = rcu_dereference(inet_protos[protocol]);
 	if (ipprot && ipprot->err_handler)
 		ipprot->err_handler(skb, info);
 	rcu_read_unlock();