rxrpc: Add keepalive for a call
We need to transmit a packet every so often to act as a keepalive for the
peer (which has a timeout from the last time it received a packet) and also
to prevent any intervening firewalls from closing the route.
Do this by resetting a timer every time we transmit a packet. If the timer
ever expires, we transmit a PING ACK packet and thereby also elicit a PING
RESPONSE ACK from the other side - which prevents our last-rx timeout from
expiring.
The timer is set to 1/6 of the last-rx timeout so that we can detect the
other side going away if it misses 6 replies in a row.
This is particularly necessary for servers where the processing of the
service function may take a significant amount of time.
Signed-off-by: David Howells <dhowells@redhat.com>
diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index 7e7b817..cdcbc79 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -519,6 +519,7 @@ struct rxrpc_call {
unsigned long ack_lost_at; /* When ACK is figured as lost */
unsigned long resend_at; /* When next resend needs to happen */
unsigned long ping_at; /* When next to send a ping */
+ unsigned long keepalive_at; /* When next to send a keepalive ping */
unsigned long expect_rx_by; /* When we expect to get a packet by */
unsigned long expect_req_by; /* When we expect to get a request DATA packet by */
unsigned long expect_term_by; /* When we expect call termination by */