af_iucv: Add automatic (source) iucv_name to bind

If a socket is bound to an address using before calling connect
it is usual to leave it to the network system to choose an appropriate
outgoing application name respective port address.
af_iucv on VM uses a counter and uses simple numbers as unique identifiers.
This behaviour was missing when af_iucv is used with HiperSockets.

This patch contains a simple approach to harmonize af_iucv's behaviour.
Signed-off-by: Philipp Hachtmann <phacht@linux.vnet.ibm.com>
Signed-off-by: Frank Blaschka <blaschka@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/iucv/af_iucv.c

@@ -682,6 +682,18 @@ struct sock *iucv_accept_dequeue(struct sock *parent, struct socket *newsock)
 	return NULL;
 }
 
+static void __iucv_auto_name(struct iucv_sock *iucv)
+{
+	char name[12];
+
+	sprintf(name, "%08x", atomic_inc_return(&iucv_sk_list.autobind_name));
+	while (__iucv_get_sock_by_name(name)) {
+		sprintf(name, "%08x",
+			atomic_inc_return(&iucv_sk_list.autobind_name));
+	}
+	memcpy(iucv->src_name, name, 8);
+}
+
 /* Bind an unbound socket */
 static int iucv_sock_bind(struct socket *sock, struct sockaddr *addr,
 			  int addr_len)
@@ -724,8 +736,12 @@ static int iucv_sock_bind(struct socket *sock, struct sockaddr *addr,
 	rcu_read_lock();
 	for_each_netdev_rcu(&init_net, dev) {
 		if (!memcmp(dev->perm_addr, uid, 8)) {
-			memcpy(iucv->src_name, sa->siucv_name, 8);
 			memcpy(iucv->src_user_id, sa->siucv_user_id, 8);
+			/* Check for unitialized siucv_name */
+			if (strncmp(sa->siucv_name, "        ", 8) == 0)
+				__iucv_auto_name(iucv);
+			else
+				memcpy(iucv->src_name, sa->siucv_name, 8);
 			sk->sk_bound_dev_if = dev->ifindex;
 			iucv->hs_dev = dev;
 			dev_hold(dev);
@@ -763,7 +779,6 @@ static int iucv_sock_bind(struct socket *sock, struct sockaddr *addr,
 static int iucv_sock_autobind(struct sock *sk)
 {
 	struct iucv_sock *iucv = iucv_sk(sk);
-	char name[12];
 	int err = 0;
 
 	if (unlikely(!pr_iucv))
@@ -772,17 +787,9 @@ static int iucv_sock_autobind(struct sock *sk)
 	memcpy(iucv->src_user_id, iucv_userid, 8);
 
 	write_lock_bh(&iucv_sk_list.lock);
-
-	sprintf(name, "%08x", atomic_inc_return(&iucv_sk_list.autobind_name));
-	while (__iucv_get_sock_by_name(name)) {
-		sprintf(name, "%08x",
-			atomic_inc_return(&iucv_sk_list.autobind_name));
-	}
-
+	__iucv_auto_name(iucv);
 	write_unlock_bh(&iucv_sk_list.lock);
 
-	memcpy(&iucv->src_name, name, 8);
-
 	if (!iucv->msglimit)
 		iucv->msglimit = IUCV_QUEUELEN_DEFAULT;