blob: e363f21a20141bb13c931fc0cd40c862c49e5829 [file] [log] [blame]
// 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;
}