VSOCK: Return VMCI_ERROR_NO_MEM when fails to allocate skb

vmci_transport_recv_dgram_cb always return VMCI_SUCESS even if we fail
to allocate skb, return VMCI_ERROR_NO_MEM instead.

Signed-off-by: Asias He <asias@redhat.com>
Acked-by: Andy King <acking@vmware.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/vmw_vsock/vmci_transport.c

@@ -625,13 +625,14 @@ static int vmci_transport_recv_dgram_cb(void *data, struct vmci_datagram *dg)
 
 	/* Attach the packet to the socket's receive queue as an sk_buff. */
 	skb = alloc_skb(size, GFP_ATOMIC);
-	if (skb) {
-		/* sk_receive_skb() will do a sock_put(), so hold here. */
-		sock_hold(sk);
-		skb_put(skb, size);
-		memcpy(skb->data, dg, size);
-		sk_receive_skb(sk, skb, 0);
-	}
+	if (!skb)
+		return VMCI_ERROR_NO_MEM;
+
+	/* sk_receive_skb() will do a sock_put(), so hold here. */
+	sock_hold(sk);
+	skb_put(skb, size);
+	memcpy(skb->data, dg, size);
+	sk_receive_skb(sk, skb, 0);
 
 	return VMCI_SUCCESS;
 }