[ICMP]: Add return code to icmp_init.

icmp_init could fail and this is normal for namespace other than initial.
So, the panic should be triggered only on init_net initialization path.

Additionally create rollback path for icmp_init as a separate function.
It will also be used later during namespace destruction.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Acked-by: Daniel Lezcano <dlezcano@fr.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/af_inet.c

@@ -1430,7 +1430,8 @@ static int __init inet_init(void)
 	 *	Set the ICMP layer up
 	 */
 
-	icmp_init();
+	if (icmp_init() < 0)
+		panic("Failed to create the ICMP control socket.\n");
 
 	/*
 	 *	Initialise the multicast router