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input.c
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// SPDX-License-Identifier: GPL-2.0-or-later
/* Processing of received RxRPC packets
*
* Copyright (C) 2020 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include "ar-internal.h"
/* Override priority when generating ACKs for received DATA */
static const u8 rxrpc_ack_priority[RXRPC_ACK__INVALID] = {
[RXRPC_ACK_IDLE] = 1,
[RXRPC_ACK_DELAY] = 2,
[RXRPC_ACK_REQUESTED] = 3,
[RXRPC_ACK_DUPLICATE] = 4,
[RXRPC_ACK_EXCEEDS_WINDOW] = 5,
[RXRPC_ACK_NOSPACE] = 6,
[RXRPC_ACK_OUT_OF_SEQUENCE] = 7,
};
static void rxrpc_proto_abort(struct rxrpc_call *call, rxrpc_seq_t seq,
enum rxrpc_abort_reason why)
{
rxrpc_abort_call(call, seq, RX_PROTOCOL_ERROR, -EBADMSG, why);
}
/*
* Do TCP-style congestion management [RFC 5681].
*/
static void rxrpc_congestion_management(struct rxrpc_call *call,
struct sk_buff *skb,
struct rxrpc_ack_summary *summary,
rxrpc_serial_t acked_serial)
{
enum rxrpc_congest_change change = rxrpc_cong_no_change;
unsigned int cumulative_acks = call->cong_cumul_acks;
unsigned int cwnd = call->cong_cwnd;
bool resend = false;
summary->flight_size =
(call->tx_top - call->acks_hard_ack) - summary->nr_acks;
if (test_and_clear_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags)) {
summary->retrans_timeo = true;
call->cong_ssthresh = max_t(unsigned int,
summary->flight_size / 2, 2);
cwnd = 1;
if (cwnd >= call->cong_ssthresh &&
call->cong_mode == RXRPC_CALL_SLOW_START) {
call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
call->cong_tstamp = skb->tstamp;
cumulative_acks = 0;
}
}
cumulative_acks += summary->nr_new_acks;
if (cumulative_acks > 255)
cumulative_acks = 255;
summary->cwnd = call->cong_cwnd;
summary->ssthresh = call->cong_ssthresh;
summary->cumulative_acks = cumulative_acks;
summary->dup_acks = call->cong_dup_acks;
switch (call->cong_mode) {
case RXRPC_CALL_SLOW_START:
if (summary->saw_nacks)
goto packet_loss_detected;
if (summary->cumulative_acks > 0)
cwnd += 1;
if (cwnd >= call->cong_ssthresh) {
call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
call->cong_tstamp = skb->tstamp;
}
goto out;
case RXRPC_CALL_CONGEST_AVOIDANCE:
if (summary->saw_nacks)
goto packet_loss_detected;
/* We analyse the number of packets that get ACK'd per RTT
* period and increase the window if we managed to fill it.
*/
if (call->peer->rtt_count == 0)
goto out;
if (ktime_before(skb->tstamp,
ktime_add_us(call->cong_tstamp,
call->peer->srtt_us >> 3)))
goto out_no_clear_ca;
change = rxrpc_cong_rtt_window_end;
call->cong_tstamp = skb->tstamp;
if (cumulative_acks >= cwnd)
cwnd++;
goto out;
case RXRPC_CALL_PACKET_LOSS:
if (!summary->saw_nacks)
goto resume_normality;
if (summary->new_low_nack) {
change = rxrpc_cong_new_low_nack;
call->cong_dup_acks = 1;
if (call->cong_extra > 1)
call->cong_extra = 1;
goto send_extra_data;
}
call->cong_dup_acks++;
if (call->cong_dup_acks < 3)
goto send_extra_data;
change = rxrpc_cong_begin_retransmission;
call->cong_mode = RXRPC_CALL_FAST_RETRANSMIT;
call->cong_ssthresh = max_t(unsigned int,
summary->flight_size / 2, 2);
cwnd = call->cong_ssthresh + 3;
call->cong_extra = 0;
call->cong_dup_acks = 0;
resend = true;
goto out;
case RXRPC_CALL_FAST_RETRANSMIT:
if (!summary->new_low_nack) {
if (summary->nr_new_acks == 0)
cwnd += 1;
call->cong_dup_acks++;
if (call->cong_dup_acks == 2) {
change = rxrpc_cong_retransmit_again;
call->cong_dup_acks = 0;
resend = true;
}
} else {
change = rxrpc_cong_progress;
cwnd = call->cong_ssthresh;
if (!summary->saw_nacks)
goto resume_normality;
}
goto out;
default:
BUG();
goto out;
}
resume_normality:
change = rxrpc_cong_cleared_nacks;
call->cong_dup_acks = 0;
call->cong_extra = 0;
call->cong_tstamp = skb->tstamp;
if (cwnd < call->cong_ssthresh)
call->cong_mode = RXRPC_CALL_SLOW_START;
else
call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
out:
cumulative_acks = 0;
out_no_clear_ca:
if (cwnd >= RXRPC_TX_MAX_WINDOW)
cwnd = RXRPC_TX_MAX_WINDOW;
call->cong_cwnd = cwnd;
call->cong_cumul_acks = cumulative_acks;
summary->mode = call->cong_mode;
trace_rxrpc_congest(call, summary, acked_serial, change);
if (resend)
rxrpc_resend(call, skb);
return;
packet_loss_detected:
change = rxrpc_cong_saw_nack;
call->cong_mode = RXRPC_CALL_PACKET_LOSS;
call->cong_dup_acks = 0;
goto send_extra_data;
send_extra_data:
/* Send some previously unsent DATA if we have some to advance the ACK
* state.
*/
if (test_bit(RXRPC_CALL_TX_LAST, &call->flags) ||
summary->nr_acks != call->tx_top - call->acks_hard_ack) {
call->cong_extra++;
wake_up(&call->waitq);
}
goto out_no_clear_ca;
}
/*
* Degrade the congestion window if we haven't transmitted a packet for >1RTT.
*/
void rxrpc_congestion_degrade(struct rxrpc_call *call)
{
ktime_t rtt, now;
if (call->cong_mode != RXRPC_CALL_SLOW_START &&
call->cong_mode != RXRPC_CALL_CONGEST_AVOIDANCE)
return;
if (__rxrpc_call_state(call) == RXRPC_CALL_CLIENT_AWAIT_REPLY)
return;
rtt = ns_to_ktime(call->peer->srtt_us * (1000 / 8));
now = ktime_get_real();
if (!ktime_before(ktime_add(call->tx_last_sent, rtt), now))
return;
trace_rxrpc_reset_cwnd(call, now);
rxrpc_inc_stat(call->rxnet, stat_tx_data_cwnd_reset);
call->tx_last_sent = now;
call->cong_mode = RXRPC_CALL_SLOW_START;
call->cong_ssthresh = max_t(unsigned int, call->cong_ssthresh,
call->cong_cwnd * 3 / 4);
call->cong_cwnd = max_t(unsigned int, call->cong_cwnd / 2, RXRPC_MIN_CWND);
}
/*
* Apply a hard ACK by advancing the Tx window.
*/
static bool rxrpc_rotate_tx_window(struct rxrpc_call *call, rxrpc_seq_t to,
struct rxrpc_ack_summary *summary)
{
struct rxrpc_txbuf *txb;
bool rot_last = false;
list_for_each_entry_rcu(txb, &call->tx_buffer, call_link, false) {
if (before_eq(txb->seq, call->acks_hard_ack))
continue;
if (txb->flags & RXRPC_LAST_PACKET) {
set_bit(RXRPC_CALL_TX_LAST, &call->flags);
rot_last = true;
}
if (txb->seq == to)
break;
}
if (rot_last)
set_bit(RXRPC_CALL_TX_ALL_ACKED, &call->flags);
_enter("%x,%x,%x,%d", to, call->acks_hard_ack, call->tx_top, rot_last);
if (call->acks_lowest_nak == call->acks_hard_ack) {
call->acks_lowest_nak = to;
} else if (after(to, call->acks_lowest_nak)) {
summary->new_low_nack = true;
call->acks_lowest_nak = to;
}
smp_store_release(&call->acks_hard_ack, to);
trace_rxrpc_txqueue(call, (rot_last ?
rxrpc_txqueue_rotate_last :
rxrpc_txqueue_rotate));
wake_up(&call->waitq);
return rot_last;
}
/*
* End the transmission phase of a call.
*
* This occurs when we get an ACKALL packet, the first DATA packet of a reply,
* or a final ACK packet.
*/
static void rxrpc_end_tx_phase(struct rxrpc_call *call, bool reply_begun,
enum rxrpc_abort_reason abort_why)
{
ASSERT(test_bit(RXRPC_CALL_TX_LAST, &call->flags));
call->resend_at = KTIME_MAX;
trace_rxrpc_timer_can(call, rxrpc_timer_trace_resend);
if (unlikely(call->cong_last_nack)) {
rxrpc_free_skb(call->cong_last_nack, rxrpc_skb_put_last_nack);
call->cong_last_nack = NULL;
}
switch (__rxrpc_call_state(call)) {
case RXRPC_CALL_CLIENT_SEND_REQUEST:
case RXRPC_CALL_CLIENT_AWAIT_REPLY:
if (reply_begun) {
rxrpc_set_call_state(call, RXRPC_CALL_CLIENT_RECV_REPLY);
trace_rxrpc_txqueue(call, rxrpc_txqueue_end);
break;
}
rxrpc_set_call_state(call, RXRPC_CALL_CLIENT_AWAIT_REPLY);
trace_rxrpc_txqueue(call, rxrpc_txqueue_await_reply);
break;
case RXRPC_CALL_SERVER_AWAIT_ACK:
rxrpc_call_completed(call);
trace_rxrpc_txqueue(call, rxrpc_txqueue_end);
break;
default:
kdebug("end_tx %s", rxrpc_call_states[__rxrpc_call_state(call)]);
rxrpc_proto_abort(call, call->tx_top, abort_why);
break;
}
}
/*
* Begin the reply reception phase of a call.
*/
static bool rxrpc_receiving_reply(struct rxrpc_call *call)
{
struct rxrpc_ack_summary summary = { 0 };
rxrpc_seq_t top = READ_ONCE(call->tx_top);
if (call->ackr_reason) {
call->delay_ack_at = KTIME_MAX;
trace_rxrpc_timer_can(call, rxrpc_timer_trace_delayed_ack);
}
if (!test_bit(RXRPC_CALL_TX_LAST, &call->flags)) {
if (!rxrpc_rotate_tx_window(call, top, &summary)) {
rxrpc_proto_abort(call, top, rxrpc_eproto_early_reply);
return false;
}
}
rxrpc_end_tx_phase(call, true, rxrpc_eproto_unexpected_reply);
return true;
}
/*
* End the packet reception phase.
*/
static void rxrpc_end_rx_phase(struct rxrpc_call *call, rxrpc_serial_t serial)
{
rxrpc_seq_t whigh = READ_ONCE(call->rx_highest_seq);
_enter("%d,%s", call->debug_id, rxrpc_call_states[__rxrpc_call_state(call)]);
trace_rxrpc_receive(call, rxrpc_receive_end, 0, whigh);
switch (__rxrpc_call_state(call)) {
case RXRPC_CALL_CLIENT_RECV_REPLY:
rxrpc_propose_delay_ACK(call, serial, rxrpc_propose_ack_terminal_ack);
rxrpc_call_completed(call);
break;
case RXRPC_CALL_SERVER_RECV_REQUEST:
rxrpc_set_call_state(call, RXRPC_CALL_SERVER_ACK_REQUEST);
call->expect_req_by = KTIME_MAX;
rxrpc_propose_delay_ACK(call, serial, rxrpc_propose_ack_processing_op);
break;
default:
break;
}
}
static void rxrpc_input_update_ack_window(struct rxrpc_call *call,
rxrpc_seq_t window, rxrpc_seq_t wtop)
{
call->ackr_window = window;
call->ackr_wtop = wtop;
}
/*
* Push a DATA packet onto the Rx queue.
*/
static void rxrpc_input_queue_data(struct rxrpc_call *call, struct sk_buff *skb,
rxrpc_seq_t window, rxrpc_seq_t wtop,
enum rxrpc_receive_trace why)
{
struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
bool last = sp->hdr.flags & RXRPC_LAST_PACKET;
__skb_queue_tail(&call->recvmsg_queue, skb);
rxrpc_input_update_ack_window(call, window, wtop);
trace_rxrpc_receive(call, last ? why + 1 : why, sp->hdr.serial, sp->hdr.seq);
if (last)
rxrpc_end_rx_phase(call, sp->hdr.serial);
}
/*
* Process a DATA packet.
*/
static void rxrpc_input_data_one(struct rxrpc_call *call, struct sk_buff *skb,
bool *_notify, rxrpc_serial_t *_ack_serial, int *_ack_reason)
{
struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
struct sk_buff *oos;
rxrpc_serial_t serial = sp->hdr.serial;
unsigned int sack = call->ackr_sack_base;
rxrpc_seq_t window = call->ackr_window;
rxrpc_seq_t wtop = call->ackr_wtop;
rxrpc_seq_t wlimit = window + call->rx_winsize - 1;
rxrpc_seq_t seq = sp->hdr.seq;
bool last = sp->hdr.flags & RXRPC_LAST_PACKET;
int ack_reason = -1;
rxrpc_inc_stat(call->rxnet, stat_rx_data);
if (sp->hdr.flags & RXRPC_REQUEST_ACK)
rxrpc_inc_stat(call->rxnet, stat_rx_data_reqack);
if (sp->hdr.flags & RXRPC_JUMBO_PACKET)
rxrpc_inc_stat(call->rxnet, stat_rx_data_jumbo);
if (last) {
if (test_and_set_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
seq + 1 != wtop)
return rxrpc_proto_abort(call, seq, rxrpc_eproto_different_last);
} else {
if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
after_eq(seq, wtop)) {
pr_warn("Packet beyond last: c=%x q=%x window=%x-%x wlimit=%x\n",
call->debug_id, seq, window, wtop, wlimit);
return rxrpc_proto_abort(call, seq, rxrpc_eproto_data_after_last);
}
}
if (after(seq, call->rx_highest_seq))
call->rx_highest_seq = seq;
trace_rxrpc_rx_data(call->debug_id, seq, serial, sp->hdr.flags);
if (before(seq, window)) {
ack_reason = RXRPC_ACK_DUPLICATE;
goto send_ack;
}
if (after(seq, wlimit)) {
ack_reason = RXRPC_ACK_EXCEEDS_WINDOW;
goto send_ack;
}
/* Queue the packet. */
if (seq == window) {
if (sp->hdr.flags & RXRPC_REQUEST_ACK)
ack_reason = RXRPC_ACK_REQUESTED;
/* Send an immediate ACK if we fill in a hole */
else if (!skb_queue_empty(&call->rx_oos_queue))
ack_reason = RXRPC_ACK_DELAY;
window++;
if (after(window, wtop)) {
trace_rxrpc_sack(call, seq, sack, rxrpc_sack_none);
wtop = window;
} else {
trace_rxrpc_sack(call, seq, sack, rxrpc_sack_advance);
sack = (sack + 1) % RXRPC_SACK_SIZE;
}
rxrpc_get_skb(skb, rxrpc_skb_get_to_recvmsg);
spin_lock(&call->recvmsg_queue.lock);
rxrpc_input_queue_data(call, skb, window, wtop, rxrpc_receive_queue);
*_notify = true;
while ((oos = skb_peek(&call->rx_oos_queue))) {
struct rxrpc_skb_priv *osp = rxrpc_skb(oos);
if (after(osp->hdr.seq, window))
break;
__skb_unlink(oos, &call->rx_oos_queue);
last = osp->hdr.flags & RXRPC_LAST_PACKET;
seq = osp->hdr.seq;
call->ackr_sack_table[sack] = 0;
trace_rxrpc_sack(call, seq, sack, rxrpc_sack_fill);
sack = (sack + 1) % RXRPC_SACK_SIZE;
window++;
rxrpc_input_queue_data(call, oos, window, wtop,
rxrpc_receive_queue_oos);
}
spin_unlock(&call->recvmsg_queue.lock);
call->ackr_sack_base = sack;
} else {
unsigned int slot;
ack_reason = RXRPC_ACK_OUT_OF_SEQUENCE;
slot = seq - window;
sack = (sack + slot) % RXRPC_SACK_SIZE;
if (call->ackr_sack_table[sack % RXRPC_SACK_SIZE]) {
ack_reason = RXRPC_ACK_DUPLICATE;
goto send_ack;
}
call->ackr_sack_table[sack % RXRPC_SACK_SIZE] |= 1;
trace_rxrpc_sack(call, seq, sack, rxrpc_sack_oos);
if (after(seq + 1, wtop)) {
wtop = seq + 1;
rxrpc_input_update_ack_window(call, window, wtop);
}
skb_queue_walk(&call->rx_oos_queue, oos) {
struct rxrpc_skb_priv *osp = rxrpc_skb(oos);
if (after(osp->hdr.seq, seq)) {
rxrpc_get_skb(skb, rxrpc_skb_get_to_recvmsg_oos);
__skb_queue_before(&call->rx_oos_queue, oos, skb);
goto oos_queued;
}
}
rxrpc_get_skb(skb, rxrpc_skb_get_to_recvmsg_oos);
__skb_queue_tail(&call->rx_oos_queue, skb);
oos_queued:
trace_rxrpc_receive(call, last ? rxrpc_receive_oos_last : rxrpc_receive_oos,
sp->hdr.serial, sp->hdr.seq);
}
send_ack:
if (ack_reason >= 0) {
if (rxrpc_ack_priority[ack_reason] > rxrpc_ack_priority[*_ack_reason]) {
*_ack_serial = serial;
*_ack_reason = ack_reason;
} else if (rxrpc_ack_priority[ack_reason] == rxrpc_ack_priority[*_ack_reason] &&
ack_reason == RXRPC_ACK_REQUESTED) {
*_ack_serial = serial;
*_ack_reason = ack_reason;
}
}
}
/*
* Split a jumbo packet and file the bits separately.
*/
static bool rxrpc_input_split_jumbo(struct rxrpc_call *call, struct sk_buff *skb)
{
struct rxrpc_jumbo_header jhdr;
struct rxrpc_skb_priv *sp = rxrpc_skb(skb), *jsp;
struct sk_buff *jskb;
rxrpc_serial_t ack_serial = 0;
unsigned int offset = sizeof(struct rxrpc_wire_header);
unsigned int len = skb->len - offset;
bool notify = false;
int ack_reason = 0;
while (sp->hdr.flags & RXRPC_JUMBO_PACKET) {
if (len < RXRPC_JUMBO_SUBPKTLEN)
goto protocol_error;
if (sp->hdr.flags & RXRPC_LAST_PACKET)
goto protocol_error;
if (skb_copy_bits(skb, offset + RXRPC_JUMBO_DATALEN,
&jhdr, sizeof(jhdr)) < 0)
goto protocol_error;
jskb = skb_clone(skb, GFP_NOFS);
if (!jskb) {
kdebug("couldn't clone");
return false;
}
rxrpc_new_skb(jskb, rxrpc_skb_new_jumbo_subpacket);
jsp = rxrpc_skb(jskb);
jsp->offset = offset;
jsp->len = RXRPC_JUMBO_DATALEN;
rxrpc_input_data_one(call, jskb, ¬ify, &ack_serial, &ack_reason);
rxrpc_free_skb(jskb, rxrpc_skb_put_jumbo_subpacket);
sp->hdr.flags = jhdr.flags;
sp->hdr._rsvd = ntohs(jhdr._rsvd);
sp->hdr.seq++;
sp->hdr.serial++;
offset += RXRPC_JUMBO_SUBPKTLEN;
len -= RXRPC_JUMBO_SUBPKTLEN;
}
sp->offset = offset;
sp->len = len;
rxrpc_input_data_one(call, skb, ¬ify, &ack_serial, &ack_reason);
if (ack_reason > 0) {
rxrpc_send_ACK(call, ack_reason, ack_serial,
rxrpc_propose_ack_input_data);
} else {
call->ackr_nr_unacked++;
rxrpc_propose_delay_ACK(call, sp->hdr.serial,
rxrpc_propose_ack_input_data);
}
if (notify) {
trace_rxrpc_notify_socket(call->debug_id, sp->hdr.serial);
rxrpc_notify_socket(call);
}
return true;
protocol_error:
return false;
}
/*
* Process a DATA packet, adding the packet to the Rx ring. The caller's
* packet ref must be passed on or discarded.
*/
static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb)
{
struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
rxrpc_serial_t serial = sp->hdr.serial;
rxrpc_seq_t seq0 = sp->hdr.seq;
_enter("{%x,%x,%x},{%u,%x}",
call->ackr_window, call->ackr_wtop, call->rx_highest_seq,
skb->len, seq0);
if (__rxrpc_call_is_complete(call))
return;
switch (__rxrpc_call_state(call)) {
case RXRPC_CALL_CLIENT_SEND_REQUEST:
case RXRPC_CALL_CLIENT_AWAIT_REPLY:
/* Received data implicitly ACKs all of the request
* packets we sent when we're acting as a client.
*/
if (!rxrpc_receiving_reply(call))
goto out_notify;
break;
case RXRPC_CALL_SERVER_RECV_REQUEST: {
unsigned long timo = READ_ONCE(call->next_req_timo);
if (timo) {
ktime_t delay = ms_to_ktime(timo);
call->expect_req_by = ktime_add(ktime_get_real(), delay);
trace_rxrpc_timer_set(call, delay, rxrpc_timer_trace_idle);
}
break;
}
default:
break;
}
if (!rxrpc_input_split_jumbo(call, skb)) {
rxrpc_proto_abort(call, sp->hdr.seq, rxrpc_badmsg_bad_jumbo);
goto out_notify;
}
return;
out_notify:
trace_rxrpc_notify_socket(call->debug_id, serial);
rxrpc_notify_socket(call);
_leave(" [queued]");
}
/*
* See if there's a cached RTT probe to complete.
*/
static void rxrpc_complete_rtt_probe(struct rxrpc_call *call,
ktime_t resp_time,
rxrpc_serial_t acked_serial,
rxrpc_serial_t ack_serial,
enum rxrpc_rtt_rx_trace type)
{
rxrpc_serial_t orig_serial;
unsigned long avail;
ktime_t sent_at;
bool matched = false;
int i;
avail = READ_ONCE(call->rtt_avail);
smp_rmb(); /* Read avail bits before accessing data. */
for (i = 0; i < ARRAY_SIZE(call->rtt_serial); i++) {
if (!test_bit(i + RXRPC_CALL_RTT_PEND_SHIFT, &avail))
continue;
sent_at = call->rtt_sent_at[i];
orig_serial = call->rtt_serial[i];
if (orig_serial == acked_serial) {
clear_bit(i + RXRPC_CALL_RTT_PEND_SHIFT, &call->rtt_avail);
smp_mb(); /* Read data before setting avail bit */
set_bit(i, &call->rtt_avail);
rxrpc_peer_add_rtt(call, type, i, acked_serial, ack_serial,
sent_at, resp_time);
matched = true;
}
/* If a later serial is being acked, then mark this slot as
* being available.
*/
if (after(acked_serial, orig_serial)) {
trace_rxrpc_rtt_rx(call, rxrpc_rtt_rx_obsolete, i,
orig_serial, acked_serial, 0, 0);
clear_bit(i + RXRPC_CALL_RTT_PEND_SHIFT, &call->rtt_avail);
smp_wmb();
set_bit(i, &call->rtt_avail);
}
}
if (!matched)
trace_rxrpc_rtt_rx(call, rxrpc_rtt_rx_lost, 9, 0, acked_serial, 0, 0);
}
/*
* Process the extra information that may be appended to an ACK packet
*/
static void rxrpc_input_ack_trailer(struct rxrpc_call *call, struct sk_buff *skb,
struct rxrpc_acktrailer *trailer)
{
struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
struct rxrpc_peer *peer;
unsigned int mtu;
bool wake = false;
u32 rwind = ntohl(trailer->rwind);
if (rwind > RXRPC_TX_MAX_WINDOW)
rwind = RXRPC_TX_MAX_WINDOW;
if (call->tx_winsize != rwind) {
if (rwind > call->tx_winsize)
wake = true;
trace_rxrpc_rx_rwind_change(call, sp->hdr.serial, rwind, wake);
call->tx_winsize = rwind;
}
mtu = min(ntohl(trailer->maxMTU), ntohl(trailer->ifMTU));
peer = call->peer;
if (mtu < peer->maxdata) {
spin_lock(&peer->lock);
peer->maxdata = mtu;
peer->mtu = mtu + peer->hdrsize;
spin_unlock(&peer->lock);
}
if (wake)
wake_up(&call->waitq);
}
/*
* Determine how many nacks from the previous ACK have now been satisfied.
*/
static rxrpc_seq_t rxrpc_input_check_prev_ack(struct rxrpc_call *call,
struct rxrpc_ack_summary *summary,
rxrpc_seq_t seq)
{
struct sk_buff *skb = call->cong_last_nack;
struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
unsigned int i, new_acks = 0, retained_nacks = 0;
rxrpc_seq_t old_seq = sp->ack.first_ack;
u8 *acks = skb->data + sizeof(struct rxrpc_wire_header) + sizeof(struct rxrpc_ackpacket);
if (after_eq(seq, old_seq + sp->ack.nr_acks)) {
summary->nr_new_acks += sp->ack.nr_nacks;
summary->nr_new_acks += seq - (old_seq + sp->ack.nr_acks);
summary->nr_retained_nacks = 0;
} else if (seq == old_seq) {
summary->nr_retained_nacks = sp->ack.nr_nacks;
} else {
for (i = 0; i < sp->ack.nr_acks; i++) {
if (acks[i] == RXRPC_ACK_TYPE_NACK) {
if (before(old_seq + i, seq))
new_acks++;
else
retained_nacks++;
}
}
summary->nr_new_acks += new_acks;
summary->nr_retained_nacks = retained_nacks;
}
return old_seq + sp->ack.nr_acks;
}
/*
* Process individual soft ACKs.
*
* Each ACK in the array corresponds to one packet and can be either an ACK or
* a NAK. If we get find an explicitly NAK'd packet we resend immediately;
* packets that lie beyond the end of the ACK list are scheduled for resend by
* the timer on the basis that the peer might just not have processed them at
* the time the ACK was sent.
*/
static void rxrpc_input_soft_acks(struct rxrpc_call *call,
struct rxrpc_ack_summary *summary,
struct sk_buff *skb,
rxrpc_seq_t seq,
rxrpc_seq_t since)
{
struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
unsigned int i, old_nacks = 0;
rxrpc_seq_t lowest_nak = seq + sp->ack.nr_acks;
u8 *acks = skb->data + sizeof(struct rxrpc_wire_header) + sizeof(struct rxrpc_ackpacket);
for (i = 0; i < sp->ack.nr_acks; i++) {
if (acks[i] == RXRPC_ACK_TYPE_ACK) {
summary->nr_acks++;
if (after_eq(seq, since))
summary->nr_new_acks++;
} else {
summary->saw_nacks = true;
if (before(seq, since)) {
/* Overlap with previous ACK */
old_nacks++;
} else {
summary->nr_new_nacks++;
sp->ack.nr_nacks++;
}
if (before(seq, lowest_nak))
lowest_nak = seq;
}
seq++;
}
if (lowest_nak != call->acks_lowest_nak) {
call->acks_lowest_nak = lowest_nak;
summary->new_low_nack = true;
}
/* We *can* have more nacks than we did - the peer is permitted to drop
* packets it has soft-acked and re-request them. Further, it is
* possible for the nack distribution to change whilst the number of
* nacks stays the same or goes down.
*/
if (old_nacks < summary->nr_retained_nacks)
summary->nr_new_acks += summary->nr_retained_nacks - old_nacks;
summary->nr_retained_nacks = old_nacks;
}
/*
* Return true if the ACK is valid - ie. it doesn't appear to have regressed
* with respect to the ack state conveyed by preceding ACKs.
*/
static bool rxrpc_is_ack_valid(struct rxrpc_call *call,
rxrpc_seq_t first_pkt, rxrpc_seq_t prev_pkt)
{
rxrpc_seq_t base = READ_ONCE(call->acks_first_seq);
if (after(first_pkt, base))
return true; /* The window advanced */
if (before(first_pkt, base))
return false; /* firstPacket regressed */
if (after_eq(prev_pkt, call->acks_prev_seq))
return true; /* previousPacket hasn't regressed. */
/* Some rx implementations put a serial number in previousPacket. */
if (after_eq(prev_pkt, base + call->tx_winsize))
return false;
return true;
}
/*
* Process an ACK packet.
*
* ack.firstPacket is the sequence number of the first soft-ACK'd/NAK'd packet
* in the ACK array. Anything before that is hard-ACK'd and may be discarded.
*
* A hard-ACK means that a packet has been processed and may be discarded; a
* soft-ACK means that the packet may be discarded and retransmission
* requested. A phase is complete when all packets are hard-ACK'd.
*/
static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)
{
struct rxrpc_ack_summary summary = { 0 };
struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
struct rxrpc_acktrailer trailer;
rxrpc_serial_t ack_serial, acked_serial;
rxrpc_seq_t first_soft_ack, hard_ack, prev_pkt, since;
int nr_acks, offset, ioffset;
_enter("");
offset = sizeof(struct rxrpc_wire_header) + sizeof(struct rxrpc_ackpacket);
ack_serial = sp->hdr.serial;
acked_serial = sp->ack.acked_serial;
first_soft_ack = sp->ack.first_ack;
prev_pkt = sp->ack.prev_ack;
nr_acks = sp->ack.nr_acks;
hard_ack = first_soft_ack - 1;
summary.ack_reason = (sp->ack.reason < RXRPC_ACK__INVALID ?
sp->ack.reason : RXRPC_ACK__INVALID);
trace_rxrpc_rx_ack(call, ack_serial, acked_serial,
first_soft_ack, prev_pkt,
summary.ack_reason, nr_acks);
rxrpc_inc_stat(call->rxnet, stat_rx_acks[summary.ack_reason]);
if (acked_serial != 0) {
switch (summary.ack_reason) {
case RXRPC_ACK_PING_RESPONSE:
rxrpc_complete_rtt_probe(call, skb->tstamp, acked_serial, ack_serial,
rxrpc_rtt_rx_ping_response);
break;
case RXRPC_ACK_REQUESTED:
rxrpc_complete_rtt_probe(call, skb->tstamp, acked_serial, ack_serial,
rxrpc_rtt_rx_requested_ack);
break;
default:
rxrpc_complete_rtt_probe(call, skb->tstamp, acked_serial, ack_serial,
rxrpc_rtt_rx_other_ack);
break;
}
}
/* If we get an EXCEEDS_WINDOW ACK from the server, it probably
* indicates that the client address changed due to NAT. The server
* lost the call because it switched to a different peer.
*/
if (unlikely(summary.ack_reason == RXRPC_ACK_EXCEEDS_WINDOW) &&
first_soft_ack == 1 &&
prev_pkt == 0 &&
rxrpc_is_client_call(call)) {
rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
0, -ENETRESET);
goto send_response;
}
/* If we get an OUT_OF_SEQUENCE ACK from the server, that can also
* indicate a change of address. However, we can retransmit the call
* if we still have it buffered to the beginning.
*/
if (unlikely(summary.ack_reason == RXRPC_ACK_OUT_OF_SEQUENCE) &&
first_soft_ack == 1 &&
prev_pkt == 0 &&
call->acks_hard_ack == 0 &&
rxrpc_is_client_call(call)) {
rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
0, -ENETRESET);
goto send_response;
}
/* Discard any out-of-order or duplicate ACKs (outside lock). */
if (!rxrpc_is_ack_valid(call, first_soft_ack, prev_pkt)) {
trace_rxrpc_rx_discard_ack(call->debug_id, ack_serial,
first_soft_ack, call->acks_first_seq,
prev_pkt, call->acks_prev_seq);
goto send_response;
}
trailer.maxMTU = 0;
ioffset = offset + nr_acks + 3;
if (skb->len >= ioffset + sizeof(trailer) &&
skb_copy_bits(skb, ioffset, &trailer, sizeof(trailer)) < 0)
return rxrpc_proto_abort(call, 0, rxrpc_badmsg_short_ack_trailer);
if (nr_acks > 0)
skb_condense(skb);
if (call->cong_last_nack) {
since = rxrpc_input_check_prev_ack(call, &summary, first_soft_ack);
rxrpc_free_skb(call->cong_last_nack, rxrpc_skb_put_last_nack);
call->cong_last_nack = NULL;
} else {
summary.nr_new_acks = first_soft_ack - call->acks_first_seq;
call->acks_lowest_nak = first_soft_ack + nr_acks;
since = first_soft_ack;
}
call->acks_latest_ts = skb->tstamp;
call->acks_first_seq = first_soft_ack;
call->acks_prev_seq = prev_pkt;
switch (summary.ack_reason) {
case RXRPC_ACK_PING:
break;
default:
if (acked_serial && after(acked_serial, call->acks_highest_serial))
call->acks_highest_serial = acked_serial;
break;
}
/* Parse rwind and mtu sizes if provided. */
if (trailer.maxMTU)
rxrpc_input_ack_trailer(call, skb, &trailer);
if (first_soft_ack == 0)
return rxrpc_proto_abort(call, 0, rxrpc_eproto_ackr_zero);
/* Ignore ACKs unless we are or have just been transmitting. */
switch (__rxrpc_call_state(call)) {
case RXRPC_CALL_CLIENT_SEND_REQUEST:
case RXRPC_CALL_CLIENT_AWAIT_REPLY:
case RXRPC_CALL_SERVER_SEND_REPLY:
case RXRPC_CALL_SERVER_AWAIT_ACK:
break;
default:
goto send_response;
}
if (before(hard_ack, call->acks_hard_ack) ||
after(hard_ack, call->tx_top))
return rxrpc_proto_abort(call, 0, rxrpc_eproto_ackr_outside_window);
if (nr_acks > call->tx_top - hard_ack)
return rxrpc_proto_abort(call, 0, rxrpc_eproto_ackr_sack_overflow);
if (after(hard_ack, call->acks_hard_ack)) {
if (rxrpc_rotate_tx_window(call, hard_ack, &summary)) {
rxrpc_end_tx_phase(call, false, rxrpc_eproto_unexpected_ack);
goto send_response;
}
}
if (nr_acks > 0) {
if (offset > (int)skb->len - nr_acks)
return rxrpc_proto_abort(call, 0, rxrpc_eproto_ackr_short_sack);
rxrpc_input_soft_acks(call, &summary, skb, first_soft_ack, since);
rxrpc_get_skb(skb, rxrpc_skb_get_last_nack);
call->cong_last_nack = skb;
}