1 files changed, 447 insertions, 0 deletions

diff --git a/net/rxrpc/call_event.c b/net/rxrpc/call_event.c
new file mode 100644
index 000000000..2a93e7b5f
--- /dev/null
+++ b/net/rxrpc/call_event.c
@@ -0,0 +1,447 @@
+// 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.
+ */
+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 {
+		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);
+		}
+	}
+}
+
+/*
+ * propose an ACK be sent
+ */
+static void __rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
+				u32 serial, bool immediate, bool background,
+				enum rxrpc_propose_ack_trace why)
+{
+	enum rxrpc_propose_ack_outcome outcome = rxrpc_propose_ack_use;
+	unsigned long expiry = rxrpc_soft_ack_delay;
+	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.
+	 */
+	_debug("prior %u %u vs %u %u",
+	       ack_reason, prior,
+	       call->ackr_reason, rxrpc_ack_priority[call->ackr_reason]);
+	if (ack_reason == call->ackr_reason) {
+		if (RXRPC_ACK_UPDATEABLE & (1 << ack_reason)) {
+			outcome = rxrpc_propose_ack_update;
+			call->ackr_serial = serial;
+		}
+		if (!immediate)
+			goto trace;
+	} else if (prior > rxrpc_ack_priority[call->ackr_reason]) {
+		call->ackr_reason = ack_reason;
+		call->ackr_serial = serial;
+	} else {
+		outcome = rxrpc_propose_ack_subsume;
+	}
+
+	switch (ack_reason) {
+	case RXRPC_ACK_REQUESTED:
+		if (rxrpc_requested_ack_delay < expiry)
+			expiry = rxrpc_requested_ack_delay;
+		if (serial == 1)
+			immediate = false;
+		break;
+
+	case RXRPC_ACK_DELAY:
+		if (rxrpc_soft_ack_delay < expiry)
+			expiry = rxrpc_soft_ack_delay;
+		break;
+
+	case RXRPC_ACK_IDLE:
+		if (rxrpc_idle_ack_delay < expiry)
+			expiry = rxrpc_idle_ack_delay;
+		break;
+
+	default:
+		immediate = true;
+		break;
+	}
+
+	if (test_bit(RXRPC_CALL_EV_ACK, &call->events)) {
+		_debug("already scheduled");
+	} else if (immediate || expiry == 0) {
+		_debug("immediate ACK %lx", call->events);
+		if (!test_and_set_bit(RXRPC_CALL_EV_ACK, &call->events) &&
+		    background)
+			rxrpc_queue_call(call);
+	} else {
+		unsigned long now = jiffies, ack_at;
+
+		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->ack_at)) {
+			WRITE_ONCE(call->ack_at, ack_at);
+			rxrpc_reduce_call_timer(call, ack_at, now,
+						rxrpc_timer_set_for_ack);
+		}
+	}
+
+trace:
+	trace_rxrpc_propose_ack(call, why, ack_reason, serial, immediate,
+				background, outcome);
+}
+
+/*
+ * propose an ACK be sent, locking the call structure
+ */
+void rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
+		       u32 serial, bool immediate, bool background,
+		       enum rxrpc_propose_ack_trace why)
+{
+	spin_lock_bh(&call->lock);
+	__rxrpc_propose_ACK(call, ack_reason, serial,
+			    immediate, background, why);
+	spin_unlock_bh(&call->lock);
+}
+
+/*
+ * 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.
+ */
+static void rxrpc_resend(struct rxrpc_call *call, unsigned long now_j)
+{
+	struct sk_buff *skb;
+	unsigned long resend_at;
+	rxrpc_seq_t cursor, seq, top;
+	ktime_t now, max_age, oldest, ack_ts;
+	int ix;
+	u8 annotation, anno_type, retrans = 0, unacked = 0;
+
+	_enter("{%d,%d}", call->tx_hard_ack, call->tx_top);
+
+	now = ktime_get_real();
+	max_age = ktime_sub_us(now, jiffies_to_usecs(call->peer->rto_j));
+
+	spin_lock_bh(&call->lock);
+
+	cursor = call->tx_hard_ack;
+	top = call->tx_top;
+	ASSERT(before_eq(cursor, top));
+	if (cursor == top)
+		goto out_unlock;
+
+	/* Scan the packet list without dropping the lock and decide which of
+	 * the packets in the Tx buffer we're going to resend and what the new
+	 * resend timeout will be.
+	 */
+	trace_rxrpc_resend(call, (cursor + 1) & RXRPC_RXTX_BUFF_MASK);
+	oldest = now;
+	for (seq = cursor + 1; before_eq(seq, top); seq++) {
+		ix = seq & RXRPC_RXTX_BUFF_MASK;
+		annotation = call->rxtx_annotations[ix];
+		anno_type = annotation & RXRPC_TX_ANNO_MASK;
+		annotation &= ~RXRPC_TX_ANNO_MASK;
+		if (anno_type == RXRPC_TX_ANNO_ACK)
+			continue;
+
+		skb = call->rxtx_buffer[ix];
+		rxrpc_see_skb(skb, rxrpc_skb_seen);
+
+		if (anno_type == RXRPC_TX_ANNO_UNACK) {
+			if (ktime_after(skb->tstamp, max_age)) {
+				if (ktime_before(skb->tstamp, oldest))
+					oldest = skb->tstamp;
+				continue;
+			}
+			if (!(annotation & RXRPC_TX_ANNO_RESENT))
+				unacked++;
+		}
+
+		/* Okay, we need to retransmit a packet. */
+		call->rxtx_annotations[ix] = RXRPC_TX_ANNO_RETRANS | annotation;
+		retrans++;
+		trace_rxrpc_retransmit(call, seq, annotation | anno_type,
+				       ktime_to_ns(ktime_sub(skb->tstamp, max_age)));
+	}
+
+	resend_at = nsecs_to_jiffies(ktime_to_ns(ktime_sub(now, oldest)));
+	resend_at += jiffies + rxrpc_get_rto_backoff(call->peer, retrans);
+	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 (!retrans) {
+		rxrpc_reduce_call_timer(call, resend_at, now_j,
+					rxrpc_timer_set_for_resend);
+		spin_unlock_bh(&call->lock);
+		ack_ts = ktime_sub(now, call->acks_latest_ts);
+		if (ktime_to_us(ack_ts) < (call->peer->srtt_us >> 3))
+			goto out;
+		rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, true, false,
+				  rxrpc_propose_ack_ping_for_lost_ack);
+		rxrpc_send_ack_packet(call, true, NULL);
+		goto out;
+	}
+
+	/* Now go through the Tx window and perform the retransmissions.  We
+	 * have to drop the lock for each send.  If an ACK comes in whilst the
+	 * lock is dropped, it may clear some of the retransmission markers for
+	 * packets that it soft-ACKs.
+	 */
+	for (seq = cursor + 1; before_eq(seq, top); seq++) {
+		ix = seq & RXRPC_RXTX_BUFF_MASK;
+		annotation = call->rxtx_annotations[ix];
+		anno_type = annotation & RXRPC_TX_ANNO_MASK;
+		if (anno_type != RXRPC_TX_ANNO_RETRANS)
+			continue;
+
+		/* We need to reset the retransmission state, but we need to do
+		 * so before we drop the lock as a new ACK/NAK may come in and
+		 * confuse things
+		 */
+		annotation &= ~RXRPC_TX_ANNO_MASK;
+		annotation |= RXRPC_TX_ANNO_UNACK | RXRPC_TX_ANNO_RESENT;
+		call->rxtx_annotations[ix] = annotation;
+
+		skb = call->rxtx_buffer[ix];
+		if (!skb)
+			continue;
+
+		rxrpc_get_skb(skb, rxrpc_skb_got);
+		spin_unlock_bh(&call->lock);
+
+		if (rxrpc_send_data_packet(call, skb, true) < 0) {
+			rxrpc_free_skb(skb, rxrpc_skb_freed);
+			return;
+		}
+
+		if (rxrpc_is_client_call(call))
+			rxrpc_expose_client_call(call);
+
+		rxrpc_free_skb(skb, rxrpc_skb_freed);
+		spin_lock_bh(&call->lock);
+		if (after(call->tx_hard_ack, seq))
+			seq = call->tx_hard_ack;
+	}
+
+out_unlock:
+	spin_unlock_bh(&call->lock);
+out:
+	_leave("");
+}
+
+/*
+ * Handle retransmission and deferred ACK/abort generation.
+ */
+void rxrpc_process_call(struct work_struct *work)
+{
+	struct rxrpc_call *call =
+		container_of(work, struct rxrpc_call, processor);
+	rxrpc_serial_t *send_ack;
+	unsigned long now, next, t;
+	unsigned int iterations = 0;
+
+	rxrpc_see_call(call);
+
+	//printk("\n--------------------\n");
+	_enter("{%d,%s,%lx}",
+	       call->debug_id, rxrpc_call_states[call->state], call->events);
+
+recheck_state:
+	/* Limit the number of times we do this before returning to the manager */
+	iterations++;
+	if (iterations > 5)
+		goto requeue;
+
+	if (test_and_clear_bit(RXRPC_CALL_EV_ABORT, &call->events)) {
+		rxrpc_send_abort_packet(call);
+		goto recheck_state;
+	}
+
+	if (call->state == RXRPC_CALL_COMPLETE) {
+		rxrpc_delete_call_timer(call);
+		goto out_put;
+	}
+
+	/* Work out if any timeouts tripped */
+	now = jiffies;
+	t = READ_ONCE(call->expect_rx_by);
+	if (time_after_eq(now, t)) {
+		trace_rxrpc_timer(call, rxrpc_timer_exp_normal, now);
+		set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
+	}
+
+	t = READ_ONCE(call->expect_req_by);
+	if (call->state == RXRPC_CALL_SERVER_RECV_REQUEST &&
+	    time_after_eq(now, t)) {
+		trace_rxrpc_timer(call, rxrpc_timer_exp_idle, now);
+		set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
+	}
+
+	t = READ_ONCE(call->expect_term_by);
+	if (time_after_eq(now, t)) {
+		trace_rxrpc_timer(call, rxrpc_timer_exp_hard, now);
+		set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
+	}
+
+	t = READ_ONCE(call->ack_at);
+	if (time_after_eq(now, t)) {
+		trace_rxrpc_timer(call, rxrpc_timer_exp_ack, now);
+		cmpxchg(&call->ack_at, t, now + MAX_JIFFY_OFFSET);
+		set_bit(RXRPC_CALL_EV_ACK, &call->events);
+	}
+
+	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_propose_ACK(call, RXRPC_ACK_PING, 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);
+		cmpxchg(&call->ping_at, t, now + MAX_JIFFY_OFFSET);
+		set_bit(RXRPC_CALL_EV_PING, &call->events);
+	}
+
+	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);
+		set_bit(RXRPC_CALL_EV_RESEND, &call->events);
+	}
+
+	/* Process events */
+	if (test_and_clear_bit(RXRPC_CALL_EV_EXPIRED, &call->events)) {
+		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("EXP", call, 0, RX_CALL_DEAD, -ECONNRESET);
+		} else {
+			rxrpc_abort_call("EXP", call, 0, RX_CALL_TIMEOUT, -ETIME);
+		}
+		set_bit(RXRPC_CALL_EV_ABORT, &call->events);
+		goto recheck_state;
+	}
+
+	send_ack = NULL;
+	if (test_and_clear_bit(RXRPC_CALL_EV_ACK_LOST, &call->events)) {
+		call->acks_lost_top = call->tx_top;
+		rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, true, false,
+				  rxrpc_propose_ack_ping_for_lost_ack);
+		send_ack = &call->acks_lost_ping;
+	}
+
+	if (test_and_clear_bit(RXRPC_CALL_EV_ACK, &call->events) ||
+	    send_ack) {
+		if (call->ackr_reason) {
+			rxrpc_send_ack_packet(call, false, send_ack);
+			goto recheck_state;
+		}
+	}
+
+	if (test_and_clear_bit(RXRPC_CALL_EV_PING, &call->events)) {
+		rxrpc_send_ack_packet(call, true, NULL);
+		goto recheck_state;
+	}
+
+	if (test_and_clear_bit(RXRPC_CALL_EV_RESEND, &call->events) &&
+	    call->state != RXRPC_CALL_CLIENT_RECV_REPLY) {
+		rxrpc_resend(call, now);
+		goto recheck_state;
+	}
+
+	/* Make sure the timer is restarted */
+	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->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))
+		goto recheck_state;
+
+	rxrpc_reduce_call_timer(call, next, now, rxrpc_timer_restart);
+
+	/* other events may have been raised since we started checking */
+	if (call->events && call->state < RXRPC_CALL_COMPLETE)
+		goto requeue;
+
+out_put:
+	rxrpc_put_call(call, rxrpc_call_put);
+out:
+	_leave("");
+	return;
+
+requeue:
+	__rxrpc_queue_call(call);
+	goto out;
+}