From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753880AbdKXOi5 (ORCPT ); Fri, 24 Nov 2017 09:38:57 -0500 Received: from mx1.redhat.com ([209.132.183.28]:44716 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753855AbdKXOiv (ORCPT ); Fri, 24 Nov 2017 09:38:51 -0500 Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH net-next 10/12] rxrpc: Add keepalive for a call From: David Howells To: netdev@vger.kernel.org Cc: dhowells@redhat.com, linux-afs@lists.infradead.org, linux-kernel@vger.kernel.org Date: Fri, 24 Nov 2017 14:38:49 +0000 Message-ID: <151153432938.27205.13363838820644394620.stgit@warthog.procyon.org.uk> In-Reply-To: <151153425958.27205.13734959199482172941.stgit@warthog.procyon.org.uk> References: <151153425958.27205.13734959199482172941.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Fri, 24 Nov 2017 14:38:50 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- include/trace/events/rxrpc.h | 6 ++++++ net/rxrpc/ar-internal.h | 1 + net/rxrpc/call_event.c | 10 ++++++++++ net/rxrpc/output.c | 23 +++++++++++++++++++++++ 4 files changed, 40 insertions(+) diff --git a/include/trace/events/rxrpc.h b/include/trace/events/rxrpc.h index 84ade8b76a19..e98fed6de497 100644 --- a/include/trace/events/rxrpc.h +++ b/include/trace/events/rxrpc.h @@ -141,6 +141,7 @@ enum rxrpc_timer_trace { rxrpc_timer_exp_ack, rxrpc_timer_exp_hard, rxrpc_timer_exp_idle, + rxrpc_timer_exp_keepalive, rxrpc_timer_exp_lost_ack, rxrpc_timer_exp_normal, rxrpc_timer_exp_ping, @@ -152,6 +153,7 @@ enum rxrpc_timer_trace { rxrpc_timer_set_for_ack, rxrpc_timer_set_for_hard, rxrpc_timer_set_for_idle, + rxrpc_timer_set_for_keepalive, rxrpc_timer_set_for_lost_ack, rxrpc_timer_set_for_normal, rxrpc_timer_set_for_ping, @@ -162,6 +164,7 @@ enum rxrpc_timer_trace { enum rxrpc_propose_ack_trace { rxrpc_propose_ack_client_tx_end, rxrpc_propose_ack_input_data, + rxrpc_propose_ack_ping_for_keepalive, rxrpc_propose_ack_ping_for_lost_ack, rxrpc_propose_ack_ping_for_lost_reply, rxrpc_propose_ack_ping_for_params, @@ -311,6 +314,7 @@ enum rxrpc_congest_change { EM(rxrpc_timer_exp_ack, "ExpAck") \ EM(rxrpc_timer_exp_hard, "ExpHrd") \ EM(rxrpc_timer_exp_idle, "ExpIdl") \ + EM(rxrpc_timer_exp_keepalive, "ExpKA ") \ EM(rxrpc_timer_exp_lost_ack, "ExpLoA") \ EM(rxrpc_timer_exp_normal, "ExpNml") \ EM(rxrpc_timer_exp_ping, "ExpPng") \ @@ -321,6 +325,7 @@ enum rxrpc_congest_change { EM(rxrpc_timer_set_for_ack, "SetAck") \ EM(rxrpc_timer_set_for_hard, "SetHrd") \ EM(rxrpc_timer_set_for_idle, "SetIdl") \ + EM(rxrpc_timer_set_for_keepalive, "KeepAl") \ EM(rxrpc_timer_set_for_lost_ack, "SetLoA") \ EM(rxrpc_timer_set_for_normal, "SetNml") \ EM(rxrpc_timer_set_for_ping, "SetPng") \ @@ -330,6 +335,7 @@ enum rxrpc_congest_change { #define rxrpc_propose_ack_traces \ EM(rxrpc_propose_ack_client_tx_end, "ClTxEnd") \ EM(rxrpc_propose_ack_input_data, "DataIn ") \ + EM(rxrpc_propose_ack_ping_for_keepalive, "KeepAlv") \ EM(rxrpc_propose_ack_ping_for_lost_ack, "LostAck") \ EM(rxrpc_propose_ack_ping_for_lost_reply, "LostRpl") \ EM(rxrpc_propose_ack_ping_for_params, "Params ") \ diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h index 7e7b817c69f0..cdcbc798f921 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 */ diff --git a/net/rxrpc/call_event.c b/net/rxrpc/call_event.c index c65666b2f39e..bda952ffe6a6 100644 --- a/net/rxrpc/call_event.c +++ b/net/rxrpc/call_event.c @@ -366,6 +366,15 @@ void rxrpc_process_call(struct work_struct *work) set_bit(RXRPC_CALL_EV_ACK_LOST, &call->events); } + t = READ_ONCE(call->keepalive_at); + if (time_after_eq(now, t)) { + trace_rxrpc_timer(call, rxrpc_timer_exp_keepalive, now); + cmpxchg(&call->keepalive_at, t, now + MAX_JIFFY_OFFSET); + rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, 0, true, true, + rxrpc_propose_ack_ping_for_keepalive); + set_bit(RXRPC_CALL_EV_PING, &call->events); + } + t = READ_ONCE(call->ping_at); if (time_after_eq(now, t)) { trace_rxrpc_timer(call, rxrpc_timer_exp_ping, now); @@ -423,6 +432,7 @@ void rxrpc_process_call(struct work_struct *work) set(call->ack_at); set(call->ack_lost_at); set(call->resend_at); + set(call->keepalive_at); set(call->ping_at); now = jiffies; 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 @@ -33,6 +33,24 @@ struct rxrpc_abort_buffer { }; /* + * 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. */ static size_t rxrpc_fill_out_ack(struct rxrpc_connection *conn, @@ -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 @@ int rxrpc_send_data_packet(struct rxrpc_call *call, struct sk_buff *skb, } } } + + rxrpc_set_keepalive(call); + _leave(" = %d [%u]", ret, call->peer->maxdata); return ret;