/* 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)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#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"
/*
* Set the timer
*/
void rxrpc_set_timer(struct rxrpc_call *call, enum rxrpc_timer_trace why,
ktime_t now)
{
unsigned long t_j, now_j = jiffies;
ktime_t t;
bool queue = false;
read_lock_bh(&call->state_lock);
if (call->state < RXRPC_CALL_COMPLETE) {
t = call->expire_at;
if (!ktime_after(t, now))
goto out;
if (!ktime_after(call->resend_at, now)) {
call->resend_at = call->expire_at;
if (!test_and_set_bit(RXRPC_CALL_EV_RESEND, &call->events))
queue = true;
} else if (ktime_before(call->resend_at, t)) {
t = call->resend_at;
}
if (!ktime_after(call->ack_at, now)) {
call->ack_at = call->expire_at;
if (!test_and_set_bit(RXRPC_CALL_EV_ACK, &call->events))
queue = true;
} else if (ktime_before(call->ack_at, t)) {
t = call->ack_at;
}
t_j = nsecs_to_jiffies(ktime_to_ns(ktime_sub(t, now)));
t_j += jiffies;
/* We have to make sure that the calculated jiffies value falls
* at or after the nsec value, or we may loop ceaselessly
* because the timer times out, but we haven't reached the nsec
* timeout yet.
*/
t_j++;
if (call->timer.expires != t_j || !timer_pending(&call->timer)) {
mod_timer(&call->timer, t_j);
trace_rxrpc_timer(call, why, now, now_j);
}
if (queue)
rxrpc_queue_call(call);
}
out:
read_unlock_bh(&call->state_lock);
}
/*
* propose an ACK be sent
*/
static void __rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
u16 skew, u32 serial, bool immediate,
bool background,
enum rxrpc_propose_ack_trace why)
{
enum rxrpc_propose_ack_outcome outcome = rxrpc_propose_ack_use;
unsigned int expiry = rxrpc_soft_ack_delay;
ktime_t now, ack_at;
s8 prior = rxrpc_ack_priority[ack_reason];
/* 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;
call->ackr_skew = skew;
}
if (!immediate)
goto trace;
} else if (prior > rxrpc_ack_priority[call->ackr_reason]) {
call->ackr_reason = ack_reason;
call->ackr_serial = serial;
call->ackr_skew = skew;
} 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_PING:
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 {
now = ktime_get_real();
ack_at = ktime_add_ms(now, expiry);
if (ktime_before(ack_at, call->ack_at)) {
call->ack_at = ack_at;
rxrpc_set_timer(call, rxrpc_timer_set_for_ack, now);
}
}
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,
u16 skew, u32 serial, bool immediate, bool background,
enum rxrpc_propose_ack_trace why)
{
spin_lock_bh(&call->lock);
__rxrpc_propose_ACK(call, ack_reason, skew, 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, ktime_t now)
{
struct rxrpc_skb_priv *sp;
struct sk_buff *skb;
rxrpc_seq_t cursor, seq, top;
ktime_t 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);
max_age = ktime_sub_ms(now, rxrpc_resend_timeout);
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.
*/
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_tx_seen);
sp = rxrpc_skb(skb);
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)));
}
call->resend_at = ktime_add_ms(oldest, rxrpc_resend_timeout);
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_set_timer(call, rxrpc_timer_set_for_resend, now);
spin_unlock_bh(&call->lock);
ack_ts = ktime_sub(now, call->acks_latest_ts);
if (ktime_to_ns(ack_ts) < call->peer->rtt)
goto out;
rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, 0, true, false,
rxrpc_propose_ack_ping_for_lost_ack);
rxrpc_send_call_packet(call, RXRPC_PACKET_TYPE_ACK);
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;
skb = call->rxtx_buffer[ix];
rxrpc_get_skb(skb, rxrpc_skb_tx_got);
spin_unlock_bh(&call->lock);
if (rxrpc_send_data_packet(call, skb, true) < 0) {
rxrpc_free_skb(skb, rxrpc_skb_tx_freed);
return;
}
if (rxrpc_is_client_call(call))
rxrpc_expose_client_call(call);
rxrpc_free_skb(skb, rxrpc_skb_tx_freed);
spin_lock_bh(&call->lock);
/* We need to clear the retransmit state, but there are two
* things we need to be aware of: A new ACK/NAK might have been
* received and the packet might have been hard-ACK'd (in which
* case it will no longer be in the buffer).
*/
if (after(seq, call->tx_hard_ack)) {
annotation = call->rxtx_annotations[ix];
anno_type = annotation & RXRPC_TX_ANNO_MASK;
if (anno_type == RXRPC_TX_ANNO_RETRANS ||
anno_type == RXRPC_TX_ANNO_NAK) {
annotation &= ~RXRPC_TX_ANNO_MASK;
annotation |= RXRPC_TX_ANNO_UNACK;
}
annotation |= RXRPC_TX_ANNO_RESENT;
call->rxtx_annotations[ix] = annotation;
}
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);
ktime_t now;
rxrpc_see_call(call);
//printk("\n--------------------\n");
_enter("{%d,%s,%lx}",
call->debug_id, rxrpc_call_states[call->state], call->events);
recheck_state:
if (test_and_clear_bit(RXRPC_CALL_EV_ABORT, &call->events)) {
rxrpc_send_call_packet(call, RXRPC_PACKET_TYPE_ABORT);
goto recheck_state;
}
if (call->state == RXRPC_CALL_COMPLETE) {
del_timer_sync(&call->timer);
goto out_put;
}
now = ktime_get_real();
if (ktime_before(call->expire_at, now)) {
rxrpc_abort_call("EXP", call, 0, RX_CALL_TIMEOUT, ETIME);
set_bit(RXRPC_CALL_EV_ABORT, &call->events);
goto 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_call_packet(call, RXRPC_PACKET_TYPE_ACK);
goto recheck_state;
}
}
if (test_and_clear_bit(RXRPC_CALL_EV_RESEND, &call->events)) {
rxrpc_resend(call, now);
goto recheck_state;
}
rxrpc_set_timer(call, rxrpc_timer_set_for_resend, now);
/* other events may have been raised since we started checking */
if (call->events && call->state < RXRPC_CALL_COMPLETE) {
__rxrpc_queue_call(call);
goto out;
}
out_put:
rxrpc_put_call(call, rxrpc_call_put);
out:
_leave("");
}
