tree 3dc5a178820b16d5eaef0484fe7751cb4f71375e
parent 77f2efcbdd7133466060198e02c6e8a170c3cd14
author David Howells <dhowells@redhat.com> 1474500571 +0100
committer David Howells <dhowells@redhat.com> 1474528884 +0100

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>