Merge fix/hv_sock_eio/6.18 into v6.18.20

* commit 'd483c85de3de96c58957510cda5eb2b24e9b3d91':
  hv_sock: Report EOF instead of -EIO for FIN

Author: chessturo

net/vmw_vsock/hyperv_transport.c

@@ -694,17 +694,29 @@ static ssize_t hvs_stream_enqueue(struct vsock_sock *vsk, struct msghdr *msg,
 static s64 hvs_stream_has_data(struct vsock_sock *vsk)
 {
 	struct hvsock *hvs = vsk->trans;
-	bool need_refill;
 	s64 ret;
 
 	if (hvs->recv_data_len > 0)
 		return hvs->recv_data_len;
 
 	switch (hvs_channel_readable_payload(hvs->chan)) {
 	case 1:
-		need_refill = !hvs->recv_desc;
-		if (!need_refill)
-			return -EIO;
+		if (hvs->recv_desc) {
+			/* Here hvs->recv_data_len is 0, so hvs->recv_desc must
+			 * be NULL unless it points to the 0-byte-payload FIN
+			 * packet: see hvs_update_recv_data().
+			 *
+			 * Here all the payload has been dequeued, but
+			 * hvs_channel_readable_payload() still returns 1,
+			 * because the VMBus ringbuffer's read_index is not
+			 * updated for the FIN packet: hvs_stream_dequeue() ->
+			 * hv_pkt_iter_next() updates the cached priv_read_index
+			 * but has no opportunity to update the read_index in
+			 * hv_pkt_iter_close() as hvs_stream_has_data() returns
+			 * 0 for the FIN packet, so it won't get dequeued.
+			 */
+			return 0;
+		}
 
 		hvs->recv_desc = hv_pkt_iter_first(hvs->chan);
 		if (!hvs->recv_desc)