Commit 415f44e4 authored by David Howells's avatar David Howells
Browse files

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: default avatarDavid Howells <dhowells@redhat.com>
parent bd1fdf8c

include/trace/events/rxrpc.h

+6 −0
Original line number Diff line number Diff line
@@ -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 ") \

net/rxrpc/ar-internal.h

+1 −0
Original line number Diff line number Diff line
@@ -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 */

net/rxrpc/call_event.c

+10 −0
Original line number Diff line number Diff line
@@ -366,6 +366,15 @@ recheck_state: 
		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 @@ recheck_state: 
	set(call->ack_at);

	set(call->ack_lost_at);

	set(call->resend_at);

	set(call->keepalive_at);

	set(call->ping_at);



	now = jiffies;

net/rxrpc/output.c

+23 −0
Original line number Diff line number Diff line
@@ -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;

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