From 415f44e43282a16ec0808c7ccfd401762e587437 Mon Sep 17 00:00:00 2001 From: David Howells Date: Fri, 24 Nov 2017 10:18:42 +0000 Subject: 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 --- net/rxrpc/output.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) (limited to 'net/rxrpc/output.c') diff --git a/net/rxrpc/output.c b/net/rxrpc/output.c index efe06edce189..42410e910aff 100644 --- a/net/rxrpc/output.c +++ b/net/rxrpc/output.c @@ -32,6 +32,24 @@ struct rxrpc_abort_buffer { __be32 abort_code; }; +/* + * Arrange for a keepalive ping a certain time after we last transmitted. This + * lets the far side know we're still interested in this call and helps keep + * the route through any intervening firewall open. + * + * Receiving a response to the ping will prevent the ->expect_rx_by timer from + * expiring. + */ +static void rxrpc_set_keepalive(struct rxrpc_call *call) +{ + unsigned long now = jiffies, keepalive_at = call->next_rx_timo / 6; + + keepalive_at += now; + WRITE_ONCE(call->keepalive_at, keepalive_at); + rxrpc_reduce_call_timer(call, keepalive_at, now, + rxrpc_timer_set_for_keepalive); +} + /* * Fill out an ACK packet. */ @@ -205,6 +223,8 @@ int rxrpc_send_ack_packet(struct rxrpc_call *call, bool ping, call->ackr_seen = top; spin_unlock_bh(&call->lock); } + + rxrpc_set_keepalive(call); } out: @@ -388,6 +408,9 @@ done: } } } + + rxrpc_set_keepalive(call); + _leave(" = %d [%u]", ret, call->peer->maxdata); return ret; -- cgit