[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>

include/net/icmp.h

@@ -48,7 +48,7 @@ struct sk_buff;
 extern void	icmp_send(struct sk_buff *skb_in,  int type, int code, __be32 info);
 extern int	icmp_rcv(struct sk_buff *skb);
 extern int	icmp_ioctl(struct sock *sk, int cmd, unsigned long arg);
-extern void	icmp_init(void);
+extern int	icmp_init(void);
 extern void	icmp_out_count(unsigned char type);
 
 /* Move into dst.h ? */

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

net/ipv4/icmp.c

@@ -1139,19 +1139,32 @@ static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
 	},
 };
 
-void __init icmp_init(void)
+static void __exit icmp_exit(void)
 {
-	struct inet_sock *inet;
 	int i;
 
 	for_each_possible_cpu(i) {
-		int err;
+		struct socket *sock;
+
+		sock = per_cpu(__icmp_socket, i);
+		if (sock == NULL)
+			continue;
+		per_cpu(__icmp_socket, i) = NULL;
+		sock_release(sock);
+	}
+}
 
+int __init icmp_init(void)
+{
+	struct inet_sock *inet;
+	int i, err;
+
+	for_each_possible_cpu(i) {
 		err = sock_create_kern(PF_INET, SOCK_RAW, IPPROTO_ICMP,
 				       &per_cpu(__icmp_socket, i));
 
 		if (err < 0)
-			panic("Failed to create the ICMP control socket.\n");
+			goto fail;
 
 		per_cpu(__icmp_socket, i)->sk->sk_allocation = GFP_ATOMIC;
 
@@ -1171,6 +1184,11 @@ void __init icmp_init(void)
 		 */
 		per_cpu(__icmp_socket, i)->sk->sk_prot->unhash(per_cpu(__icmp_socket, i)->sk);
 	}
+	return 0;
+
+fail:
+	icmp_exit();
+	return err;
 }
 
 EXPORT_SYMBOL(icmp_err_convert);