VSOCK: Only check error on skb_recv_datagram when skb is NULL

If skb_recv_datagram returns an skb, we should ignore the err
value returned. Otherwise, datagram receives will return EAGAIN
when they have to wait for a datagram.
Acked-by: Adit Ranadive <aditr@vmware.com>
Signed-off-by: Jorgen Hansen <jhansen@vmware.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/vmw_vsock/vmci_transport.c

@@ -1735,11 +1735,8 @@ static int vmci_transport_dgram_dequeue(struct vsock_sock *vsk,
 	/* Retrieve the head sk_buff from the socket's receive queue. */
 	err = 0;
 	skb = skb_recv_datagram(&vsk->sk, flags, noblock, &err);
-	if (err)
-		return err;
-
 	if (!skb)
-		return -EAGAIN;
+		return err;
 
 	dg = (struct vmci_datagram *)skb->data;
 	if (!dg)
@@ -2154,7 +2151,7 @@ module_exit(vmci_transport_exit);
 
 MODULE_AUTHOR("VMware, Inc.");
 MODULE_DESCRIPTION("VMCI transport for Virtual Sockets");
-MODULE_VERSION("1.0.3.0-k");
+MODULE_VERSION("1.0.4.0-k");
 MODULE_LICENSE("GPL v2");
 MODULE_ALIAS("vmware_vsock");
 MODULE_ALIAS_NETPROTO(PF_VSOCK);