1 files changed, 497 insertions, 0 deletions

diff --git a/net/rxrpc/call_event.c b/net/rxrpc/call_event.c
new file mode 100644
index 000000000000..fec59d9338b9
--- /dev/null
+++ b/net/rxrpc/call_event.c
@@ -0,0 +1,497 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Management of Tx window, Tx resend, ACKs and out-of-sequence reception
+ *
+ * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/circ_buf.h>
+#include <linux/net.h>
+#include <linux/skbuff.h>
+#include <linux/slab.h>
+#include <linux/udp.h>
+#include <net/sock.h>
+#include <net/af_rxrpc.h>
+#include "ar-internal.h"
+
+/*
+ * Propose a PING ACK be sent.
+ */
+void rxrpc_propose_ping(struct rxrpc_call *call, u32 serial,
+			enum rxrpc_propose_ack_trace why)
+{
+	ktime_t delay = ms_to_ktime(READ_ONCE(rxrpc_idle_ack_delay));
+	ktime_t now = ktime_get_real();
+	ktime_t ping_at = ktime_add(now, delay);
+
+	trace_rxrpc_propose_ack(call, why, RXRPC_ACK_PING, serial);
+	if (ktime_before(ping_at, call->ping_at)) {
+		call->ping_at = ping_at;
+		trace_rxrpc_timer_set(call, delay, rxrpc_timer_trace_ping);
+	}
+}
+
+/*
+ * Propose a DELAY ACK be sent in the future.
+ */
+void rxrpc_propose_delay_ACK(struct rxrpc_call *call, rxrpc_serial_t serial,
+			     enum rxrpc_propose_ack_trace why)
+{
+	ktime_t now = ktime_get_real(), delay;
+
+	trace_rxrpc_propose_ack(call, why, RXRPC_ACK_DELAY, serial);
+
+	if (call->srtt_us)
+		delay = (call->srtt_us >> 3) * NSEC_PER_USEC;
+	else
+		delay = ms_to_ktime(READ_ONCE(rxrpc_soft_ack_delay));
+	ktime_add_ms(delay, call->tx_backoff);
+
+	call->delay_ack_at = ktime_add(now, delay);
+	trace_rxrpc_timer_set(call, delay, rxrpc_timer_trace_delayed_ack);
+}
+
+/*
+ * Retransmit one or more packets.
+ */
+static bool rxrpc_retransmit_data(struct rxrpc_call *call,
+				  struct rxrpc_send_data_req *req)
+{
+	struct rxrpc_txqueue *tq = req->tq;
+	unsigned int ix = req->seq & RXRPC_TXQ_MASK;
+	struct rxrpc_txbuf *txb = tq->bufs[ix];
+
+	_enter("%x,%x,%x,%x", tq->qbase, req->seq, ix, txb->debug_id);
+
+	req->retrans = true;
+	trace_rxrpc_retransmit(call, req, txb);
+
+	txb->flags |= RXRPC_TXBUF_RESENT;
+	rxrpc_send_data_packet(call, req);
+	rxrpc_inc_stat(call->rxnet, stat_tx_data_retrans);
+
+	req->tq		= NULL;
+	req->n		= 0;
+	req->did_send	= true;
+	req->now	= ktime_get_real();
+	return true;
+}
+
+/*
+ * Perform retransmission of NAK'd and unack'd packets.
+ */
+static void rxrpc_resend(struct rxrpc_call *call)
+{
+	struct rxrpc_send_data_req req = {
+		.now	= ktime_get_real(),
+		.trace	= rxrpc_txdata_retransmit,
+	};
+	struct rxrpc_txqueue *tq;
+
+	_enter("{%d,%d}", call->tx_bottom, call->tx_top);
+
+	trace_rxrpc_resend(call, call->acks_highest_serial);
+
+	/* Scan the transmission queue, looking for lost packets. */
+	for (tq = call->tx_queue; tq; tq = tq->next) {
+		unsigned long lost = tq->segment_lost;
+
+		if (after(tq->qbase, call->tx_transmitted))
+			break;
+
+		_debug("retr %16lx %u c=%08x [%x]",
+		       tq->segment_acked, tq->nr_reported_acks, call->debug_id, tq->qbase);
+		_debug("lost %16lx", lost);
+
+		trace_rxrpc_resend_lost(call, tq, lost);
+		while (lost) {
+			unsigned int ix = __ffs(lost);
+			struct rxrpc_txbuf *txb = tq->bufs[ix];
+
+			__clear_bit(ix, &lost);
+			rxrpc_see_txbuf(txb, rxrpc_txbuf_see_lost);
+
+			req.tq  = tq;
+			req.seq = tq->qbase + ix;
+			req.n   = 1;
+			rxrpc_retransmit_data(call, &req);
+		}
+	}
+
+	rxrpc_get_rto_backoff(call, req.did_send);
+	_leave("");
+}
+
+/*
+ * Resend the highest-seq DATA packet so far transmitted for RACK-TLP [RFC8985 7.3].
+ */
+void rxrpc_resend_tlp(struct rxrpc_call *call)
+{
+	struct rxrpc_send_data_req req = {
+		.now		= ktime_get_real(),
+		.seq		= call->tx_transmitted,
+		.n		= 1,
+		.tlp_probe	= true,
+		.trace		= rxrpc_txdata_tlp_retransmit,
+	};
+
+	/* There's a chance it'll be on the tail segment of the queue. */
+	req.tq = READ_ONCE(call->tx_qtail);
+	if (req.tq &&
+	    before(call->tx_transmitted, req.tq->qbase + RXRPC_NR_TXQUEUE)) {
+		rxrpc_retransmit_data(call, &req);
+		return;
+	}
+
+	for (req.tq = call->tx_queue; req.tq; req.tq = req.tq->next) {
+		if (after_eq(call->tx_transmitted, req.tq->qbase) &&
+		    before(call->tx_transmitted, req.tq->qbase + RXRPC_NR_TXQUEUE)) {
+			rxrpc_retransmit_data(call, &req);
+			return;
+		}
+	}
+}
+
+/*
+ * Start transmitting the reply to a service.  This cancels the need to ACK the
+ * request if we haven't yet done so.
+ */
+static void rxrpc_begin_service_reply(struct rxrpc_call *call)
+{
+	rxrpc_set_call_state(call, RXRPC_CALL_SERVER_SEND_REPLY);
+	if (call->ackr_reason == RXRPC_ACK_DELAY)
+		call->ackr_reason = 0;
+	call->delay_ack_at = KTIME_MAX;
+	trace_rxrpc_timer_can(call, rxrpc_timer_trace_delayed_ack);
+}
+
+/*
+ * Close the transmission phase.  After this point there is no more data to be
+ * transmitted in the call.
+ */
+static void rxrpc_close_tx_phase(struct rxrpc_call *call)
+{
+	_debug("________awaiting reply/ACK__________");
+
+	switch (__rxrpc_call_state(call)) {
+	case RXRPC_CALL_CLIENT_SEND_REQUEST:
+		rxrpc_set_call_state(call, RXRPC_CALL_CLIENT_AWAIT_REPLY);
+		break;
+	case RXRPC_CALL_SERVER_SEND_REPLY:
+		rxrpc_set_call_state(call, RXRPC_CALL_SERVER_AWAIT_ACK);
+		break;
+	default:
+		break;
+	}
+}
+
+/*
+ * Transmit some as-yet untransmitted data, to a maximum of the supplied limit.
+ */
+static void rxrpc_transmit_fresh_data(struct rxrpc_call *call, unsigned int limit,
+				      enum rxrpc_txdata_trace trace)
+{
+	int space = rxrpc_tx_window_space(call);
+
+	if (!test_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
+		if (call->send_top == call->tx_top)
+			return;
+		rxrpc_expose_client_call(call);
+	}
+
+	while (space > 0) {
+		struct rxrpc_send_data_req req = {
+			.now	= ktime_get_real(),
+			.seq	= call->tx_transmitted + 1,
+			.n	= 0,
+			.trace	= trace,
+		};
+		struct rxrpc_txqueue *tq;
+		struct rxrpc_txbuf *txb;
+		rxrpc_seq_t send_top, seq;
+		int limit = min(space, max(call->peer->pmtud_jumbo, 1));
+
+		/* Order send_top before the contents of the new txbufs and
+		 * txqueue pointers
+		 */
+		send_top = smp_load_acquire(&call->send_top);
+		if (call->tx_top == send_top)
+			break;
+
+		trace_rxrpc_transmit(call, send_top, space);
+
+		tq = call->tx_qtail;
+		seq = call->tx_top;
+		trace_rxrpc_tq(call, tq, seq, rxrpc_tq_decant);
+
+		do {
+			int ix;
+
+			seq++;
+			ix = seq & RXRPC_TXQ_MASK;
+			if (!ix) {
+				tq = tq->next;
+				trace_rxrpc_tq(call, tq, seq, rxrpc_tq_decant_advance);
+			}
+			if (!req.tq)
+				req.tq = tq;
+			txb = tq->bufs[ix];
+			req.n++;
+			if (!txb->jumboable)
+				break;
+		} while (req.n < limit && before(seq, send_top));
+
+		if (txb->flags & RXRPC_LAST_PACKET) {
+			rxrpc_close_tx_phase(call);
+			tq = NULL;
+		}
+		call->tx_qtail = tq;
+		call->tx_top = seq;
+
+		space -= req.n;
+		rxrpc_send_data_packet(call, &req);
+	}
+}
+
+void rxrpc_transmit_some_data(struct rxrpc_call *call, unsigned int limit,
+			      enum rxrpc_txdata_trace trace)
+{
+	switch (__rxrpc_call_state(call)) {
+	case RXRPC_CALL_SERVER_ACK_REQUEST:
+		if (call->tx_bottom == READ_ONCE(call->send_top))
+			return;
+		rxrpc_begin_service_reply(call);
+		fallthrough;
+
+	case RXRPC_CALL_SERVER_SEND_REPLY:
+	case RXRPC_CALL_CLIENT_SEND_REQUEST:
+		if (!rxrpc_tx_window_space(call))
+			return;
+		if (call->tx_bottom == READ_ONCE(call->send_top)) {
+			rxrpc_inc_stat(call->rxnet, stat_tx_data_underflow);
+			return;
+		}
+		rxrpc_transmit_fresh_data(call, limit, trace);
+		break;
+	default:
+		return;
+	}
+}
+
+/*
+ * Ping the other end to fill our RTT cache and to retrieve the rwind
+ * and MTU parameters.
+ */
+static void rxrpc_send_initial_ping(struct rxrpc_call *call)
+{
+	if (call->rtt_count < 3 ||
+	    ktime_before(ktime_add_ms(call->rtt_last_req, 1000),
+			 ktime_get_real()))
+		rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
+			       rxrpc_propose_ack_ping_for_params);
+}
+
+/*
+ * Handle retransmission and deferred ACK/abort generation.
+ */
+bool rxrpc_input_call_event(struct rxrpc_call *call)
+{
+	struct sk_buff *skb;
+	ktime_t now, t;
+	bool did_receive = false, saw_ack = false;
+	s32 abort_code;
+
+	rxrpc_see_call(call, rxrpc_call_see_input);
+
+	//printk("\n--------------------\n");
+	_enter("{%d,%s,%lx}",
+	       call->debug_id, rxrpc_call_states[__rxrpc_call_state(call)],
+	       call->events);
+
+	/* Handle abort request locklessly, vs rxrpc_propose_abort(). */
+	abort_code = smp_load_acquire(&call->send_abort);
+	if (abort_code) {
+		rxrpc_abort_call(call, 0, call->send_abort, call->send_abort_err,
+				 call->send_abort_why);
+		goto out;
+	}
+
+	do {
+		skb = __skb_dequeue(&call->rx_queue);
+		if (skb) {
+			struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
+
+			if (__rxrpc_call_is_complete(call) ||
+			    skb->mark == RXRPC_SKB_MARK_ERROR) {
+				rxrpc_free_skb(skb, rxrpc_skb_put_call_rx);
+				goto out;
+			}
+
+			saw_ack |= sp->hdr.type == RXRPC_PACKET_TYPE_ACK;
+
+			rxrpc_input_call_packet(call, skb);
+			rxrpc_free_skb(skb, rxrpc_skb_put_call_rx);
+			did_receive = true;
+		}
+
+		t = ktime_sub(call->rack_timo_at, ktime_get_real());
+		if (t <= 0) {
+			trace_rxrpc_timer_exp(call, t,
+					      rxrpc_timer_trace_rack_off + call->rack_timer_mode);
+			call->rack_timo_at = KTIME_MAX;
+			rxrpc_rack_timer_expired(call, t);
+		}
+
+	} while (!skb_queue_empty(&call->rx_queue));
+
+	/* If we see our async-event poke, check for timeout trippage. */
+	now = ktime_get_real();
+	t = ktime_sub(call->expect_rx_by, now);
+	if (t <= 0) {
+		trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_expect_rx);
+		goto expired;
+	}
+
+	t = ktime_sub(call->expect_req_by, now);
+	if (t <= 0) {
+		call->expect_req_by = KTIME_MAX;
+		if (__rxrpc_call_state(call) == RXRPC_CALL_SERVER_RECV_REQUEST) {
+			trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_idle);
+			goto expired;
+		}
+	}
+
+	t = ktime_sub(READ_ONCE(call->expect_term_by), now);
+	if (t <= 0) {
+		trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_hard);
+		goto expired;
+	}
+
+	t = ktime_sub(call->delay_ack_at, now);
+	if (t <= 0) {
+		trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_delayed_ack);
+		call->delay_ack_at = KTIME_MAX;
+		rxrpc_send_ACK(call, RXRPC_ACK_DELAY, 0,
+			       rxrpc_propose_ack_delayed_ack);
+	}
+
+	t = ktime_sub(call->ping_at, now);
+	if (t <= 0) {
+		trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_ping);
+		call->ping_at = KTIME_MAX;
+		rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
+			       rxrpc_propose_ack_ping_for_keepalive);
+	}
+
+	now = ktime_get_real();
+	t = ktime_sub(call->keepalive_at, now);
+	if (t <= 0) {
+		trace_rxrpc_timer_exp(call, t, rxrpc_timer_trace_keepalive);
+		call->keepalive_at = KTIME_MAX;
+		rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
+			       rxrpc_propose_ack_ping_for_keepalive);
+	}
+
+	if (test_and_clear_bit(RXRPC_CALL_EV_INITIAL_PING, &call->events))
+		rxrpc_send_initial_ping(call);
+
+	rxrpc_transmit_some_data(call, UINT_MAX, rxrpc_txdata_new_data);
+
+	if (saw_ack)
+		rxrpc_congestion_degrade(call);
+
+	if (did_receive &&
+	    (__rxrpc_call_state(call) == RXRPC_CALL_CLIENT_SEND_REQUEST ||
+	     __rxrpc_call_state(call) == RXRPC_CALL_SERVER_SEND_REPLY)) {
+		t = ktime_sub(call->rack_timo_at, ktime_get_real());
+		trace_rxrpc_rack(call, t);
+	}
+
+	/* Process events */
+	if (test_and_clear_bit(RXRPC_CALL_EV_ACK_LOST, &call->events))
+		rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
+			       rxrpc_propose_ack_ping_for_lost_ack);
+
+	if (call->tx_nr_lost > 0 &&
+	    __rxrpc_call_state(call) != RXRPC_CALL_CLIENT_RECV_REPLY &&
+	    !test_bit(RXRPC_CALL_TX_ALL_ACKED, &call->flags))
+		rxrpc_resend(call);
+
+	if (test_and_clear_bit(RXRPC_CALL_RX_IS_IDLE, &call->flags))
+		rxrpc_send_ACK(call, RXRPC_ACK_IDLE, 0,
+			       rxrpc_propose_ack_rx_idle);
+
+	if (call->ackr_nr_unacked > 2) {
+		if (call->rtt_count < 3)
+			rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
+				       rxrpc_propose_ack_ping_for_rtt);
+		else if (ktime_before(ktime_add_ms(call->rtt_last_req, 1000),
+				      ktime_get_real()))
+			rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
+				       rxrpc_propose_ack_ping_for_old_rtt);
+		else
+			rxrpc_send_ACK(call, RXRPC_ACK_IDLE, 0,
+				       rxrpc_propose_ack_input_data);
+	}
+
+	/* Make sure the timer is restarted */
+	if (!__rxrpc_call_is_complete(call)) {
+		ktime_t next = READ_ONCE(call->expect_term_by), delay;
+
+#define set(T) { ktime_t _t = (T); if (ktime_before(_t, next)) next = _t; }
+
+		set(call->expect_req_by);
+		set(call->expect_rx_by);
+		set(call->delay_ack_at);
+		set(call->rack_timo_at);
+		set(call->keepalive_at);
+		set(call->ping_at);
+
+		now = ktime_get_real();
+		delay = ktime_sub(next, now);
+		if (delay <= 0) {
+			rxrpc_poke_call(call, rxrpc_call_poke_timer_now);
+		} else {
+			unsigned long nowj = jiffies, delayj, nextj;
+
+			delayj = umax(nsecs_to_jiffies(delay), 1);
+			nextj = nowj + delayj;
+			if (time_before(nextj, call->timer.expires) ||
+			    !timer_pending(&call->timer)) {
+				trace_rxrpc_timer_restart(call, delay, delayj);
+				timer_reduce(&call->timer, nextj);
+			}
+		}
+	}
+
+out:
+	if (__rxrpc_call_is_complete(call)) {
+		timer_delete_sync(&call->timer);
+		if (!test_bit(RXRPC_CALL_DISCONNECTED, &call->flags))
+			rxrpc_disconnect_call(call);
+		if (call->security)
+			call->security->free_call_crypto(call);
+	} else {
+		if (did_receive &&
+		    call->peer->ackr_adv_pmtud &&
+		    call->peer->pmtud_pending)
+			rxrpc_send_probe_for_pmtud(call);
+	}
+	_leave("");
+	return true;
+
+expired:
+	if (test_bit(RXRPC_CALL_RX_HEARD, &call->flags) &&
+	    (int)call->conn->hi_serial - (int)call->rx_serial > 0) {
+		trace_rxrpc_call_reset(call);
+		rxrpc_abort_call(call, 0, RX_CALL_DEAD, -ECONNRESET,
+				 rxrpc_abort_call_reset);
+	} else {
+		rxrpc_abort_call(call, 0, RX_CALL_TIMEOUT, -ETIME,
+				 rxrpc_abort_call_timeout);
+	}
+	goto out;
+}