Commit a5af7e1f authored by David Howells's avatar David Howells
Browse files

rxrpc: Fix loss of PING RESPONSE ACK production due to PING ACKs 



Separate the output of PING ACKs from the output of other sorts of ACK so
that if we receive a PING ACK and schedule transmission of a PING RESPONSE
ACK, the response doesn't get cancelled by a PING ACK we happen to be
scheduling transmission of at the same time.

If a PING RESPONSE gets lost, the other side might just sit there waiting
for it and refuse to proceed otherwise.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
parent 26cb02aa

net/rxrpc/ar-internal.h

+9 −3
Original line number Diff line number Diff line
@@ -398,6 +398,7 @@ enum rxrpc_call_flag { 
	RXRPC_CALL_EXPOSED,		/* The call was exposed to the world */

	RXRPC_CALL_RX_LAST,		/* Received the last packet (at rxtx_top) */

	RXRPC_CALL_TX_LAST,		/* Last packet in Tx buffer (at rxtx_top) */

	RXRPC_CALL_SEND_PING,		/* A ping will need to be sent */

	RXRPC_CALL_PINGING,		/* Ping in process */

	RXRPC_CALL_RETRANS_TIMEOUT,	/* Retransmission due to timeout occurred */

};
@@ -410,6 +411,7 @@ enum rxrpc_call_event { 
	RXRPC_CALL_EV_ABORT,		/* need to generate abort */

	RXRPC_CALL_EV_TIMER,		/* Timer expired */

	RXRPC_CALL_EV_RESEND,		/* Tx resend required */

	RXRPC_CALL_EV_PING,		/* Ping send required */

};



/*
@@ -466,6 +468,7 @@ struct rxrpc_call { 
	struct rxrpc_sock __rcu	*socket;	/* socket responsible */

	ktime_t			ack_at;		/* When deferred ACK needs to happen */

	ktime_t			resend_at;	/* When next resend needs to happen */

	ktime_t			ping_at;	/* When next to send a ping */

	ktime_t			expire_at;	/* When the call times out */

	struct timer_list	timer;		/* Combined event timer */

	struct work_struct	processor;	/* Event processor */
@@ -558,8 +561,10 @@ struct rxrpc_call { 
	rxrpc_seq_t		ackr_prev_seq;	/* previous sequence number received */

	rxrpc_seq_t		ackr_consumed;	/* Highest packet shown consumed */

	rxrpc_seq_t		ackr_seen;	/* Highest packet shown seen */

	rxrpc_serial_t		ackr_ping;	/* Last ping sent */

	ktime_t			ackr_ping_time;	/* Time last ping sent */



	/* ping management */

	rxrpc_serial_t		ping_serial;	/* Last ping sent */

	ktime_t			ping_time;	/* Time last ping sent */



	/* transmission-phase ACK management */

	ktime_t			acks_latest_ts;	/* Timestamp of latest ACK received */
@@ -730,6 +735,7 @@ enum rxrpc_timer_trace { 
	rxrpc_timer_init_for_reply,

	rxrpc_timer_expired,

	rxrpc_timer_set_for_ack,

	rxrpc_timer_set_for_ping,

	rxrpc_timer_set_for_resend,

	rxrpc_timer_set_for_send,

	rxrpc_timer__nr_trace
@@ -1068,7 +1074,7 @@ extern const s8 rxrpc_ack_priority[]; 
/*

 * output.c

 */

int rxrpc_send_ack_packet(struct rxrpc_call *);

int rxrpc_send_ack_packet(struct rxrpc_call *, bool);

int rxrpc_send_abort_packet(struct rxrpc_call *);

int rxrpc_send_data_packet(struct rxrpc_call *, struct sk_buff *, bool);

void rxrpc_reject_packets(struct rxrpc_local *);

net/rxrpc/call_event.c

+44 −4
Original line number Diff line number Diff line
@@ -54,6 +54,14 @@ void rxrpc_set_timer(struct rxrpc_call *call, enum rxrpc_timer_trace why, 
			t = call->ack_at;

		}



		if (!ktime_after(call->ping_at, now)) {

			call->ping_at = call->expire_at;

			if (!test_and_set_bit(RXRPC_CALL_EV_PING, &call->events))

				queue = true;

		} else if (ktime_before(call->ping_at, t)) {

			t = call->ping_at;

		}



		t_j = nsecs_to_jiffies(ktime_to_ns(ktime_sub(t, now)));

		t_j += jiffies;
@@ -77,6 +85,27 @@ out: 
	read_unlock_bh(&call->state_lock);

}



/*

 * Propose a PING ACK be sent.

 */

static void rxrpc_propose_ping(struct rxrpc_call *call,

			       bool immediate, bool background)

{

	if (immediate) {

		if (background &&

		    !test_and_set_bit(RXRPC_CALL_EV_PING, &call->events))

			rxrpc_queue_call(call);

	} else {

		ktime_t now = ktime_get_real();

		ktime_t ping_at = ktime_add_ms(now, rxrpc_idle_ack_delay);



		if (ktime_before(ping_at, call->ping_at)) {

			call->ping_at = ping_at;

			rxrpc_set_timer(call, rxrpc_timer_set_for_ping, now);

		}

	}

}



/*

 * propose an ACK be sent

 */
@@ -90,6 +119,14 @@ static void __rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason, 
	ktime_t now, ack_at;

	s8 prior = rxrpc_ack_priority[ack_reason];



	/* Pings are handled specially because we don't want to accidentally

	 * lose a ping response by subsuming it into a ping.

	 */

	if (ack_reason == RXRPC_ACK_PING) {

		rxrpc_propose_ping(call, immediate, background);

		goto trace;

	}



	/* Update DELAY, IDLE, REQUESTED and PING_RESPONSE ACK serial

	 * numbers, but we don't alter the timeout.

	 */
@@ -125,7 +162,6 @@ static void __rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason, 
			expiry = rxrpc_soft_ack_delay;

		break;



	case RXRPC_ACK_PING:

	case RXRPC_ACK_IDLE:

		if (rxrpc_idle_ack_delay < expiry)

			expiry = rxrpc_idle_ack_delay;
@@ -253,7 +289,7 @@ static void rxrpc_resend(struct rxrpc_call *call, ktime_t now) 
			goto out;

		rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, 0, true, false,

				  rxrpc_propose_ack_ping_for_lost_ack);

		rxrpc_send_ack_packet(call);

		rxrpc_send_ack_packet(call, true);

		goto out;

	}
@@ -345,13 +381,17 @@ recheck_state: 
	}



	if (test_and_clear_bit(RXRPC_CALL_EV_ACK, &call->events)) {

		call->ack_at = call->expire_at;

		if (call->ackr_reason) {

			rxrpc_send_ack_packet(call);

			rxrpc_send_ack_packet(call, false);

			goto recheck_state;

		}

	}



	if (test_and_clear_bit(RXRPC_CALL_EV_PING, &call->events)) {

		rxrpc_send_ack_packet(call, true);

		goto recheck_state;

	}



	if (test_and_clear_bit(RXRPC_CALL_EV_RESEND, &call->events)) {

		rxrpc_resend(call, now);

		goto recheck_state;

net/rxrpc/call_object.c

+1 −0
Original line number Diff line number Diff line
@@ -205,6 +205,7 @@ static void rxrpc_start_call_timer(struct rxrpc_call *call) 
	expire_at = ktime_add_ms(now, rxrpc_max_call_lifetime);

	call->expire_at = expire_at;

	call->ack_at = expire_at;

	call->ping_at = expire_at;

	call->resend_at = expire_at;

	call->timer.expires = jiffies + LONG_MAX / 2;

	rxrpc_set_timer(call, rxrpc_timer_begin, now);

net/rxrpc/input.c

+2 −2
Original line number Diff line number Diff line
@@ -625,9 +625,9 @@ static void rxrpc_input_ping_response(struct rxrpc_call *call, 
	rxrpc_serial_t ping_serial;

	ktime_t ping_time;



	ping_time = call->ackr_ping_time;

	ping_time = call->ping_time;

	smp_rmb();

	ping_serial = call->ackr_ping;

	ping_serial = call->ping_serial;



	if (!test_bit(RXRPC_CALL_PINGING, &call->flags) ||

	    before(orig_serial, ping_serial))

net/rxrpc/misc.c

+1 −1
Original line number Diff line number Diff line
@@ -93,7 +93,6 @@ const s8 rxrpc_ack_priority[] = { 
	[RXRPC_ACK_EXCEEDS_WINDOW]	= 6,

	[RXRPC_ACK_NOSPACE]		= 7,

	[RXRPC_ACK_PING_RESPONSE]	= 8,

	[RXRPC_ACK_PING]		= 9,

};



const char rxrpc_ack_names[RXRPC_ACK__INVALID + 1][4] = {
@@ -197,6 +196,7 @@ const char rxrpc_timer_traces[rxrpc_timer__nr_trace][8] = { 
	[rxrpc_timer_expired]			= "*EXPR*",

	[rxrpc_timer_init_for_reply]		= "IniRpl",

	[rxrpc_timer_set_for_ack]		= "SetAck",

	[rxrpc_timer_set_for_ping]		= "SetPng",

	[rxrpc_timer_set_for_send]		= "SetTx ",

	[rxrpc_timer_set_for_resend]		= "SetRTx",

};

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