rxrpc: Add re-sent Tx annotation

Add a Tx-phase annotation for packet buffers to indicate that a buffer has
already been retransmitted.  This will be used by future congestion
management.  Re-retransmissions of a packet don't affect the congestion
window managment in the same way as initial retransmissions.

Signed-off-by: David Howells <dhowells@redhat.com>
diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index f021df4..dcf54e3 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -505,6 +505,8 @@
 #define RXRPC_TX_ANNO_UNACK	1
 #define RXRPC_TX_ANNO_NAK	2
 #define RXRPC_TX_ANNO_RETRANS	3
+#define RXRPC_TX_ANNO_MASK	0x03
+#define RXRPC_TX_ANNO_RESENT	0x04
 #define RXRPC_RX_ANNO_JUMBO	0x3f		/* Jumbo subpacket number + 1 if not zero */
 #define RXRPC_RX_ANNO_JLAST	0x40		/* Set if last element of a jumbo packet */
 #define RXRPC_RX_ANNO_VERIFIED	0x80		/* Set if verified and decrypted */