[PATCH 01/41] rxrpc: Fix RTT determination to use PING ACKs as a source

[David Howells]

Fix RTT determination to use a PING ACK that is in marked as being in
response to a DATA packet as the response from which RTT can be calculated
from in lieu of a REQUESTED ACK.  The server may send the latter instead of
the former.

Fixes: 4700c4d80b7b ("rxrpc: Fix loss of RTT samples due to interposed ACK")
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
cc: Marc Dionne <marc.dionne@xxxxxxxxxxxx>
cc: linux-afs@xxxxxxxxxxxxxxxxxxx
---
 net/rxrpc/input.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c
index 030d64f282f3..fc0d404f3b91 100644
--- a/net/rxrpc/input.c
+++ b/net/rxrpc/input.c
@@ -806,6 +806,10 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)
 		rxrpc_complete_rtt_probe(call, skb->tstamp, acked_serial, ack_serial,
 					 rxrpc_rtt_rx_ping_response);
 		break;
+	case RXRPC_ACK_PING:
+		if (acked_serial == 0)
+			break;
+		fallthrough;
 	case RXRPC_ACK_REQUESTED:
 		rxrpc_complete_rtt_probe(call, skb->tstamp, acked_serial, ack_serial,
 					 rxrpc_rtt_rx_requested_ack);