1 files changed, 547 insertions, 0 deletions

diff --git a/net/rxrpc/call_event.c b/net/rxrpc/call_event.c
new file mode 100644
index 000000000..e363f21a2
--- /dev/null
+++ b/net/rxrpc/call_event.c
@@ -0,0 +1,547 @@
+// 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)
+{
+	unsigned long now = jiffies;
+	unsigned long ping_at = now + rxrpc_idle_ack_delay;
+
+	if (time_before(ping_at, call->ping_at)) {
+		WRITE_ONCE(call->ping_at, ping_at);
+		rxrpc_reduce_call_timer(call, ping_at, now,
+					rxrpc_timer_set_for_ping);
+		trace_rxrpc_propose_ack(call, why, RXRPC_ACK_PING, serial);
+	}
+}
+
+/*
+ * 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)
+{
+	unsigned long expiry = rxrpc_soft_ack_delay;
+	unsigned long now = jiffies, ack_at;
+
+	call->ackr_serial = serial;
+
+	if (rxrpc_soft_ack_delay < expiry)
+		expiry = rxrpc_soft_ack_delay;
+	if (call->peer->srtt_us != 0)
+		ack_at = usecs_to_jiffies(call->peer->srtt_us >> 3);
+	else
+		ack_at = expiry;
+
+	ack_at += READ_ONCE(call->tx_backoff);
+	ack_at += now;
+	if (time_before(ack_at, call->delay_ack_at)) {
+		WRITE_ONCE(call->delay_ack_at, ack_at);
+		rxrpc_reduce_call_timer(call, ack_at, now,
+					rxrpc_timer_set_for_ack);
+	}
+
+	trace_rxrpc_propose_ack(call, why, RXRPC_ACK_DELAY, serial);
+}
+
+/*
+ * Queue an ACK for immediate transmission.
+ */
+void rxrpc_send_ACK(struct rxrpc_call *call, u8 ack_reason,
+		    rxrpc_serial_t serial, enum rxrpc_propose_ack_trace why)
+{
+	struct rxrpc_txbuf *txb;
+
+	if (test_bit(RXRPC_CALL_DISCONNECTED, &call->flags))
+		return;
+
+	rxrpc_inc_stat(call->rxnet, stat_tx_acks[ack_reason]);
+
+	txb = rxrpc_alloc_txbuf(call, RXRPC_PACKET_TYPE_ACK,
+				rcu_read_lock_held() ? GFP_ATOMIC | __GFP_NOWARN : GFP_NOFS);
+	if (!txb) {
+		kleave(" = -ENOMEM");
+		return;
+	}
+
+	txb->ack_why		= why;
+	txb->wire.seq		= 0;
+	txb->wire.type		= RXRPC_PACKET_TYPE_ACK;
+	txb->wire.flags		|= RXRPC_SLOW_START_OK;
+	txb->ack.bufferSpace	= 0;
+	txb->ack.maxSkew	= 0;
+	txb->ack.firstPacket	= 0;
+	txb->ack.previousPacket	= 0;
+	txb->ack.serial		= htonl(serial);
+	txb->ack.reason		= ack_reason;
+	txb->ack.nAcks		= 0;
+
+	trace_rxrpc_send_ack(call, why, ack_reason, serial);
+	rxrpc_send_ack_packet(call, txb);
+	rxrpc_put_txbuf(txb, rxrpc_txbuf_put_ack_tx);
+}
+
+/*
+ * Handle congestion being detected by the retransmit timeout.
+ */
+static void rxrpc_congestion_timeout(struct rxrpc_call *call)
+{
+	set_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags);
+}
+
+/*
+ * Perform retransmission of NAK'd and unack'd packets.
+ */
+void rxrpc_resend(struct rxrpc_call *call, struct sk_buff *ack_skb)
+{
+	struct rxrpc_ackpacket *ack = NULL;
+	struct rxrpc_txbuf *txb;
+	unsigned long resend_at;
+	rxrpc_seq_t transmitted = READ_ONCE(call->tx_transmitted);
+	ktime_t now, max_age, oldest, ack_ts;
+	bool unacked = false;
+	unsigned int i;
+	LIST_HEAD(retrans_queue);
+
+	_enter("{%d,%d}", call->acks_hard_ack, call->tx_top);
+
+	now = ktime_get_real();
+	max_age = ktime_sub_us(now, jiffies_to_usecs(call->peer->rto_j));
+	oldest = now;
+
+	if (list_empty(&call->tx_buffer))
+		goto no_resend;
+
+	if (list_empty(&call->tx_buffer))
+		goto no_further_resend;
+
+	trace_rxrpc_resend(call, ack_skb);
+	txb = list_first_entry(&call->tx_buffer, struct rxrpc_txbuf, call_link);
+
+	/* Scan the soft ACK table without dropping the lock and resend any
+	 * explicitly NAK'd packets.
+	 */
+	if (ack_skb) {
+		ack = (void *)ack_skb->data + sizeof(struct rxrpc_wire_header);
+
+		for (i = 0; i < ack->nAcks; i++) {
+			rxrpc_seq_t seq;
+
+			if (ack->acks[i] & 1)
+				continue;
+			seq = ntohl(ack->firstPacket) + i;
+			if (after(txb->seq, transmitted))
+				break;
+			if (after(txb->seq, seq))
+				continue; /* A new hard ACK probably came in */
+			list_for_each_entry_from(txb, &call->tx_buffer, call_link) {
+				if (txb->seq == seq)
+					goto found_txb;
+			}
+			goto no_further_resend;
+
+		found_txb:
+			if (after(ntohl(txb->wire.serial), call->acks_highest_serial))
+				continue; /* Ack point not yet reached */
+
+			rxrpc_see_txbuf(txb, rxrpc_txbuf_see_unacked);
+
+			if (list_empty(&txb->tx_link)) {
+				list_add_tail(&txb->tx_link, &retrans_queue);
+				set_bit(RXRPC_TXBUF_RESENT, &txb->flags);
+			}
+
+			trace_rxrpc_retransmit(call, txb->seq,
+					       ktime_to_ns(ktime_sub(txb->last_sent,
+								     max_age)));
+
+			if (list_is_last(&txb->call_link, &call->tx_buffer))
+				goto no_further_resend;
+			txb = list_next_entry(txb, call_link);
+		}
+	}
+
+	/* Fast-forward through the Tx queue to the point the peer says it has
+	 * seen.  Anything between the soft-ACK table and that point will get
+	 * ACK'd or NACK'd in due course, so don't worry about it here; here we
+	 * need to consider retransmitting anything beyond that point.
+	 *
+	 * Note that ACK for a packet can beat the update of tx_transmitted.
+	 */
+	if (after_eq(READ_ONCE(call->acks_prev_seq), READ_ONCE(call->tx_transmitted)))
+		goto no_further_resend;
+
+	list_for_each_entry_from(txb, &call->tx_buffer, call_link) {
+		if (before_eq(txb->seq, READ_ONCE(call->acks_prev_seq)))
+			continue;
+		if (after(txb->seq, READ_ONCE(call->tx_transmitted)))
+			break; /* Not transmitted yet */
+
+		if (ack && ack->reason == RXRPC_ACK_PING_RESPONSE &&
+		    before(ntohl(txb->wire.serial), ntohl(ack->serial)))
+			goto do_resend; /* Wasn't accounted for by a more recent ping. */
+
+		if (ktime_after(txb->last_sent, max_age)) {
+			if (ktime_before(txb->last_sent, oldest))
+				oldest = txb->last_sent;
+			continue;
+		}
+
+	do_resend:
+		unacked = true;
+		if (list_empty(&txb->tx_link)) {
+			list_add_tail(&txb->tx_link, &retrans_queue);
+			set_bit(RXRPC_TXBUF_RESENT, &txb->flags);
+			rxrpc_inc_stat(call->rxnet, stat_tx_data_retrans);
+		}
+	}
+
+no_further_resend:
+no_resend:
+	resend_at = nsecs_to_jiffies(ktime_to_ns(ktime_sub(now, oldest)));
+	resend_at += jiffies + rxrpc_get_rto_backoff(call->peer,
+						     !list_empty(&retrans_queue));
+	WRITE_ONCE(call->resend_at, resend_at);
+
+	if (unacked)
+		rxrpc_congestion_timeout(call);
+
+	/* If there was nothing that needed retransmission then it's likely
+	 * that an ACK got lost somewhere.  Send a ping to find out instead of
+	 * retransmitting data.
+	 */
+	if (list_empty(&retrans_queue)) {
+		rxrpc_reduce_call_timer(call, resend_at, jiffies,
+					rxrpc_timer_set_for_resend);
+		ack_ts = ktime_sub(now, call->acks_latest_ts);
+		if (ktime_to_us(ack_ts) < (call->peer->srtt_us >> 3))
+			goto out;
+		rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
+			       rxrpc_propose_ack_ping_for_lost_ack);
+		goto out;
+	}
+
+	/* Retransmit the queue */
+	while ((txb = list_first_entry_or_null(&retrans_queue,
+					       struct rxrpc_txbuf, tx_link))) {
+		list_del_init(&txb->tx_link);
+		rxrpc_transmit_one(call, txb);
+	}
+
+out:
+	_leave("");
+}
+
+/*
+ * 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)
+{
+	unsigned long now = jiffies;
+
+	rxrpc_set_call_state(call, RXRPC_CALL_SERVER_SEND_REPLY);
+	WRITE_ONCE(call->delay_ack_at, now + MAX_JIFFY_OFFSET);
+	if (call->ackr_reason == RXRPC_ACK_DELAY)
+		call->ackr_reason = 0;
+	trace_rxrpc_timer(call, rxrpc_timer_init_for_send_reply, now);
+}
+
+/*
+ * 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;
+	}
+}
+
+static bool rxrpc_tx_window_has_space(struct rxrpc_call *call)
+{
+	unsigned int winsize = min_t(unsigned int, call->tx_winsize,
+				     call->cong_cwnd + call->cong_extra);
+	rxrpc_seq_t window = call->acks_hard_ack, wtop = window + winsize;
+	rxrpc_seq_t tx_top = call->tx_top;
+	int space;
+
+	space = wtop - tx_top;
+	return space > 0;
+}
+
+/*
+ * Decant some if the sendmsg prepared queue into the transmission buffer.
+ */
+static void rxrpc_decant_prepared_tx(struct rxrpc_call *call)
+{
+	struct rxrpc_txbuf *txb;
+
+	if (!test_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
+		if (list_empty(&call->tx_sendmsg))
+			return;
+		rxrpc_expose_client_call(call);
+	}
+
+	while ((txb = list_first_entry_or_null(&call->tx_sendmsg,
+					       struct rxrpc_txbuf, call_link))) {
+		spin_lock(&call->tx_lock);
+		list_del(&txb->call_link);
+		spin_unlock(&call->tx_lock);
+
+		call->tx_top = txb->seq;
+		list_add_tail(&txb->call_link, &call->tx_buffer);
+
+		if (txb->wire.flags & RXRPC_LAST_PACKET)
+			rxrpc_close_tx_phase(call);
+
+		rxrpc_transmit_one(call, txb);
+
+		if (!rxrpc_tx_window_has_space(call))
+			break;
+	}
+}
+
+static void rxrpc_transmit_some_data(struct rxrpc_call *call)
+{
+	switch (__rxrpc_call_state(call)) {
+	case RXRPC_CALL_SERVER_ACK_REQUEST:
+		if (list_empty(&call->tx_sendmsg))
+			return;
+		rxrpc_begin_service_reply(call);
+		fallthrough;
+
+	case RXRPC_CALL_SERVER_SEND_REPLY:
+	case RXRPC_CALL_CLIENT_SEND_REQUEST:
+		if (!rxrpc_tx_window_has_space(call))
+			return;
+		if (list_empty(&call->tx_sendmsg)) {
+			rxrpc_inc_stat(call->rxnet, stat_tx_data_underflow);
+			return;
+		}
+		rxrpc_decant_prepared_tx(call);
+		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->peer->rtt_count < 3 ||
+	    ktime_before(ktime_add_ms(call->peer->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)
+{
+	unsigned long now, next, t;
+	rxrpc_serial_t ackr_serial;
+	bool resend = false, expired = 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);
+
+	if (__rxrpc_call_is_complete(call))
+		goto out;
+
+	/* 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;
+	}
+
+	if (skb && skb->mark == RXRPC_SKB_MARK_ERROR)
+		goto out;
+
+	/* If we see our async-event poke, check for timeout trippage. */
+	now = jiffies;
+	t = READ_ONCE(call->expect_rx_by);
+	if (time_after_eq(now, t)) {
+		trace_rxrpc_timer(call, rxrpc_timer_exp_normal, now);
+		expired = true;
+	}
+
+	t = READ_ONCE(call->expect_req_by);
+	if (__rxrpc_call_state(call) == RXRPC_CALL_SERVER_RECV_REQUEST &&
+	    time_after_eq(now, t)) {
+		trace_rxrpc_timer(call, rxrpc_timer_exp_idle, now);
+		expired = true;
+	}
+
+	t = READ_ONCE(call->expect_term_by);
+	if (time_after_eq(now, t)) {
+		trace_rxrpc_timer(call, rxrpc_timer_exp_hard, now);
+		expired = true;
+	}
+
+	t = READ_ONCE(call->delay_ack_at);
+	if (time_after_eq(now, t)) {
+		trace_rxrpc_timer(call, rxrpc_timer_exp_ack, now);
+		cmpxchg(&call->delay_ack_at, t, now + MAX_JIFFY_OFFSET);
+		ackr_serial = xchg(&call->ackr_serial, 0);
+		rxrpc_send_ACK(call, RXRPC_ACK_DELAY, ackr_serial,
+			       rxrpc_propose_ack_ping_for_lost_ack);
+	}
+
+	t = READ_ONCE(call->ack_lost_at);
+	if (time_after_eq(now, t)) {
+		trace_rxrpc_timer(call, rxrpc_timer_exp_lost_ack, now);
+		cmpxchg(&call->ack_lost_at, t, now + MAX_JIFFY_OFFSET);
+		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_send_ACK(call, RXRPC_ACK_PING, 0,
+			       rxrpc_propose_ack_ping_for_keepalive);
+	}
+
+	t = READ_ONCE(call->ping_at);
+	if (time_after_eq(now, t)) {
+		trace_rxrpc_timer(call, rxrpc_timer_exp_ping, now);
+		cmpxchg(&call->ping_at, t, now + MAX_JIFFY_OFFSET);
+		rxrpc_send_ACK(call, RXRPC_ACK_PING, 0,
+			       rxrpc_propose_ack_ping_for_keepalive);
+	}
+
+	t = READ_ONCE(call->resend_at);
+	if (time_after_eq(now, t)) {
+		trace_rxrpc_timer(call, rxrpc_timer_exp_resend, now);
+		cmpxchg(&call->resend_at, t, now + MAX_JIFFY_OFFSET);
+		resend = true;
+	}
+
+	if (skb)
+		rxrpc_input_call_packet(call, skb);
+
+	rxrpc_transmit_some_data(call);
+
+	if (skb) {
+		struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
+
+		if (sp->hdr.type == RXRPC_PACKET_TYPE_ACK)
+			rxrpc_congestion_degrade(call);
+	}
+
+	if (test_and_clear_bit(RXRPC_CALL_EV_INITIAL_PING, &call->events))
+		rxrpc_send_initial_ping(call);
+
+	/* Process events */
+	if (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;
+	}
+
+	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 (resend && __rxrpc_call_state(call) != RXRPC_CALL_CLIENT_RECV_REPLY)
+		rxrpc_resend(call, NULL);
+
+	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->peer->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->peer->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)) {
+		next = call->expect_rx_by;
+
+#define set(T) { t = READ_ONCE(T); if (time_before(t, next)) next = t; }
+
+		set(call->expect_req_by);
+		set(call->expect_term_by);
+		set(call->delay_ack_at);
+		set(call->ack_lost_at);
+		set(call->resend_at);
+		set(call->keepalive_at);
+		set(call->ping_at);
+
+		now = jiffies;
+		if (time_after_eq(now, next))
+			rxrpc_poke_call(call, rxrpc_call_poke_timer_now);
+
+		rxrpc_reduce_call_timer(call, next, now, rxrpc_timer_restart);
+	}
+
+out:
+	if (__rxrpc_call_is_complete(call)) {
+		del_timer_sync(&call->timer);
+		if (!test_bit(RXRPC_CALL_DISCONNECTED, &call->flags))
+			rxrpc_disconnect_call(call);
+		if (call->security)
+			call->security->free_call_crypto(call);
+	}
+	if (call->acks_hard_ack != call->tx_bottom)
+		rxrpc_shrink_call_tx_buffer(call);
+	_leave("");
+	return true;
+}