rxrpc: Obtain RTT data by requesting ACKs on DATA packets

In addition to sending a PING ACK to gain RTT data, we can set the
RXRPC_REQUEST_ACK flag on a DATA packet and get a REQUESTED-ACK ACK.  The
ACK packet contains the serial number of the packet it is in response to,
so we can look through the Tx buffer for a matching DATA packet.

This requires that the data packets be stamped with the time of
transmission as a ktime rather than having the resend_at time in jiffies.

This further requires the resend code to do the resend determination in
ktimes and convert to jiffies to set the timer.

Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/net/rxrpc/misc.c b/net/rxrpc/misc.c
index 56e668352fc7..0d425e707f22 100644
--- a/net/rxrpc/misc.c
+++ b/net/rxrpc/misc.c
@@ -68,9 +68,9 @@ unsigned int rxrpc_rx_mtu = 5692;
 unsigned int rxrpc_rx_jumbo_max = 4;
 
 /*
- * Time till packet resend (in jiffies).
+ * Time till packet resend (in milliseconds).
  */
-unsigned int rxrpc_resend_timeout = 4 * HZ;
+unsigned int rxrpc_resend_timeout = 4 * 1000;
 
 const char *const rxrpc_pkts[] = {
 	"?00",
@@ -186,8 +186,10 @@ const char rxrpc_recvmsg_traces[rxrpc_recvmsg__nr_trace][5] = {
 
 const char rxrpc_rtt_tx_traces[rxrpc_rtt_tx__nr_trace][5] = {
 	[rxrpc_rtt_tx_ping]		= "PING",
+	[rxrpc_rtt_tx_data]		= "DATA",
 };
 
 const char rxrpc_rtt_rx_traces[rxrpc_rtt_rx__nr_trace][5] = {
 	[rxrpc_rtt_rx_ping_response]	= "PONG",
+	[rxrpc_rtt_rx_requested_ack]	= "RACK",
 };