// 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 [RFC5681].
 */
static void rxrpc_congestion_management(struct rxrpc_call *call,
                                        struct rxrpc_ack_summary *summary)
{
        summary->change = rxrpc_cong_no_change;
        summary->in_flight = rxrpc_tx_in_flight(call);

        if (test_and_clear_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags)) {
                summary->retrans_timeo = true;
                call->cong_ssthresh = umax(summary->in_flight / 2, 2);
                call->cong_cwnd = 1;
                if (call->cong_cwnd >= call->cong_ssthresh &&
                    call->cong_ca_state == RXRPC_CA_SLOW_START) {
                        call->cong_ca_state = RXRPC_CA_CONGEST_AVOIDANCE;
                        call->cong_tstamp = call->acks_latest_ts;
                        call->cong_cumul_acks = 0;
                }
        }

        call->cong_cumul_acks += summary->nr_new_sacks;
        call->cong_cumul_acks += summary->nr_new_hacks;
        if (call->cong_cumul_acks > 255)
                call->cong_cumul_acks = 255;

        switch (call->cong_ca_state) {
        case RXRPC_CA_SLOW_START:
                if (call->acks_nr_snacks > 0)
                        goto packet_loss_detected;
                if (call->cong_cumul_acks > 0)
                        call->cong_cwnd += 1;
                if (call->cong_cwnd >= call->cong_ssthresh) {
                        call->cong_ca_state = RXRPC_CA_CONGEST_AVOIDANCE;
                        call->cong_tstamp = call->acks_latest_ts;
                }
                goto out;

        case RXRPC_CA_CONGEST_AVOIDANCE:
                if (call->acks_nr_snacks > 0)
                        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->rtt_count == 0)
                        goto out;
                if (ktime_before(call->acks_latest_ts,
                                 ktime_add_us(call->cong_tstamp,
                                              call->srtt_us >> 3)))
                        goto out_no_clear_ca;
                summary->change = rxrpc_cong_rtt_window_end;
                call->cong_tstamp = call->acks_latest_ts;
                if (call->cong_cumul_acks >= call->cong_cwnd)
                        call->cong_cwnd++;
                goto out;

        case RXRPC_CA_PACKET_LOSS:
                if (call->acks_nr_snacks == 0)
                        goto resume_normality;

                if (summary->new_low_snack) {
                        summary->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;

                summary->change = rxrpc_cong_begin_retransmission;
                call->cong_ca_state = RXRPC_CA_FAST_RETRANSMIT;
                call->cong_ssthresh = umax(summary->in_flight / 2, 2);
                call->cong_cwnd = call->cong_ssthresh + 3;
                call->cong_extra = 0;
                call->cong_dup_acks = 0;
                summary->need_retransmit = true;
                summary->in_fast_or_rto_recovery = true;
                goto out;

        case RXRPC_CA_FAST_RETRANSMIT:
                rxrpc_tlp_init(call);
                summary->in_fast_or_rto_recovery = true;
                if (!summary->new_low_snack) {
                        if (summary->nr_new_sacks == 0)
                                call->cong_cwnd += 1;
                        call->cong_dup_acks++;
                        if (call->cong_dup_acks == 2) {
                                summary->change = rxrpc_cong_retransmit_again;
                                call->cong_dup_acks = 0;
                                summary->need_retransmit = true;
                        }
                } else {
                        summary->change = rxrpc_cong_progress;
                        call->cong_cwnd = call->cong_ssthresh;
                        if (call->acks_nr_snacks == 0) {
                                summary->exiting_fast_or_rto_recovery = true;
                                goto resume_normality;
                        }
                }
                goto out;

        default:
                BUG();
                goto out;
        }

resume_normality:
        summary->change = rxrpc_cong_cleared_nacks;
        call->cong_dup_acks = 0;
        call->cong_extra = 0;
        call->cong_tstamp = call->acks_latest_ts;
        if (call->cong_cwnd < call->cong_ssthresh)
                call->cong_ca_state = RXRPC_CA_SLOW_START;
        else
                call->cong_ca_state = RXRPC_CA_CONGEST_AVOIDANCE;
out:
        call->cong_cumul_acks = 0;
out_no_clear_ca:
        if (call->cong_cwnd >= RXRPC_TX_MAX_WINDOW)
                call->cong_cwnd = RXRPC_TX_MAX_WINDOW;
        trace_rxrpc_congest(call, summary);
        return;

packet_loss_detected:
        summary->change = rxrpc_cong_saw_nack;
        call->cong_ca_state = RXRPC_CA_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) ||
            call->acks_nr_sacks != call->tx_top - call->tx_bottom) {
                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, time_since;

        if (call->cong_ca_state != RXRPC_CA_SLOW_START &&
            call->cong_ca_state != RXRPC_CA_CONGEST_AVOIDANCE)
                return;
        if (__rxrpc_call_state(call) == RXRPC_CALL_CLIENT_AWAIT_ACK ||
            __rxrpc_call_state(call) == RXRPC_CALL_CLIENT_AWAIT_REPLY)
                return;

        rtt = ns_to_ktime(call->srtt_us * (NSEC_PER_USEC / 8));
        now = ktime_get_real();
        time_since = ktime_sub(now, call->tx_last_sent);
        if (ktime_before(time_since, rtt))
                return;

        trace_rxrpc_reset_cwnd(call, time_since, rtt);
        rxrpc_inc_stat(call->rxnet, stat_tx_data_cwnd_reset);
        call->tx_last_sent = now;
        call->cong_ca_state = RXRPC_CA_SLOW_START;
        call->cong_ssthresh = umax(call->cong_ssthresh, call->cong_cwnd * 3 / 4);
        call->cong_cwnd = umax(call->cong_cwnd / 2, RXRPC_MIN_CWND);
}

/*
 * Add an RTT sample derived from an ACK'd DATA packet.
 */
static void rxrpc_add_data_rtt_sample(struct rxrpc_call *call,
                                      struct rxrpc_ack_summary *summary,
                                      struct rxrpc_txqueue *tq,
                                      int ix)
{
        ktime_t xmit_ts = ktime_add_us(tq->xmit_ts_base, tq->segment_xmit_ts[ix]);

        rxrpc_call_add_rtt(call, rxrpc_rtt_rx_data_ack, -1,
                           summary->acked_serial, summary->ack_serial,
                           xmit_ts, call->acks_latest_ts);
        __clear_bit(ix, &tq->rtt_samples); /* Prevent repeat RTT sample */
}

/*
 * 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_txqueue *tq = call->tx_queue;
        rxrpc_seq_t seq = call->tx_bottom + 1;
        bool rot_last = false, trace = false;

        _enter("%x,%x", call->tx_bottom, to);

        trace_rxrpc_tx_rotate(call, seq, to);
        trace_rxrpc_tq(call, tq, seq, rxrpc_tq_rotate);

        if (call->acks_lowest_nak == call->tx_bottom) {
                call->acks_lowest_nak = to;
        } else if (after(to, call->acks_lowest_nak)) {
                summary->new_low_snack = true;
                call->acks_lowest_nak = to;
        }

        if (after(seq, to))
                return false;

        /* We may have a left over fully-consumed buffer at the front that we
         * couldn't drop before (rotate_and_keep below).
         */
        if (seq == call->tx_qbase + RXRPC_NR_TXQUEUE) {
                call->tx_qbase += RXRPC_NR_TXQUEUE;
                call->tx_queue = tq->next;
                trace_rxrpc_tq(call, tq, seq, rxrpc_tq_rotate_and_free);
                kfree(tq);
                tq = call->tx_queue;
        }

        while (before_eq(seq, to)) {
                unsigned int ix = seq - call->tx_qbase;

                _debug("tq=%x seq=%x i=%d f=%x", tq->qbase, seq, ix, tq->bufs[ix]->flags);
                if (tq->bufs[ix]->flags & RXRPC_LAST_PACKET) {
                        set_bit(RXRPC_CALL_TX_LAST, &call->flags);
                        rot_last = true;
                }

                if (summary->acked_serial == tq->segment_serial[ix] &&
                    test_bit(ix, &tq->rtt_samples))
                        rxrpc_add_data_rtt_sample(call, summary, tq, ix);

                if (ix == tq->nr_reported_acks) {
                        /* Packet directly hard ACK'd. */
                        tq->nr_reported_acks++;
                        rxrpc_input_rack_one(call, summary, tq, ix);
                        if (seq == call->tlp_seq)
                                summary->tlp_probe_acked = true;
                        summary->nr_new_hacks++;
                        __set_bit(ix, &tq->segment_acked);
                        trace_rxrpc_rotate(call, tq, summary, seq, rxrpc_rotate_trace_hack);
                } else if (test_bit(ix, &tq->segment_acked)) {
                        /* Soft ACK -> hard ACK. */
                        call->acks_nr_sacks--;
                        trace_rxrpc_rotate(call, tq, summary, seq, rxrpc_rotate_trace_sack);
                } else {
                        /* Soft NAK -> hard ACK. */
                        call->acks_nr_snacks--;
                        rxrpc_input_rack_one(call, summary, tq, ix);
                        if (seq == call->tlp_seq)
                                summary->tlp_probe_acked = true;
                        summary->nr_new_hacks++;
                        __set_bit(ix, &tq->segment_acked);
                        trace_rxrpc_rotate(call, tq, summary, seq, rxrpc_rotate_trace_snak);
                }

                call->tx_nr_sent--;
                if (__test_and_clear_bit(ix, &tq->segment_lost))
                        call->tx_nr_lost--;
                if (__test_and_clear_bit(ix, &tq->segment_retransmitted))
                        call->tx_nr_resent--;
                __clear_bit(ix, &tq->ever_retransmitted);

                rxrpc_put_txbuf(tq->bufs[ix], rxrpc_txbuf_put_rotated);
                tq->bufs[ix] = NULL;

                WRITE_ONCE(call->tx_bottom, seq);
                trace_rxrpc_txqueue(call, (rot_last ?
                                           rxrpc_txqueue_rotate_last :
                                           rxrpc_txqueue_rotate));

                seq++;
                trace = true;
                if (!(seq & RXRPC_TXQ_MASK)) {
                        trace_rxrpc_rack_update(call, summary);
                        trace = false;
                        prefetch(tq->next);
                        if (tq != call->tx_qtail) {
                                call->tx_qbase += RXRPC_NR_TXQUEUE;
                                call->tx_queue = tq->next;
                                trace_rxrpc_tq(call, tq, seq, rxrpc_tq_rotate_and_free);
                                kfree(tq);
                                tq = call->tx_queue;
                        } else {
                                trace_rxrpc_tq(call, tq, seq, rxrpc_tq_rotate_and_keep);
                                tq = NULL;
                                break;
                        }
                }
        }

        if (trace)
                trace_rxrpc_rack_update(call, summary);

        if (rot_last) {
                set_bit(RXRPC_CALL_TX_ALL_ACKED, &call->flags);
                if (tq) {
                        trace_rxrpc_tq(call, tq, seq, rxrpc_tq_rotate_and_free);
                        kfree(tq);
                        call->tx_queue = NULL;
                }
        }

        _debug("%x,%x,%x,%d", to, call->tx_bottom, call->tx_top, rot_last);

        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->rack_timer_mode = RXRPC_CALL_RACKTIMER_OFF;
        call->rack_timo_at = KTIME_MAX;
        trace_rxrpc_rack_timer(call, 0, false);
        trace_rxrpc_timer_can(call, rxrpc_timer_trace_rack_off + call->rack_timer_mode);

        switch (__rxrpc_call_state(call)) {
        case RXRPC_CALL_CLIENT_SEND_REQUEST:
        case RXRPC_CALL_CLIENT_AWAIT_ACK:
        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);
        }

        /* Deal with an apparent reply coming in before we've got the request
         * queued or transmitted.
         */
        if (!test_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
                rxrpc_proto_abort(call, top, rxrpc_eproto_early_reply);
                return false;
        }

        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;

        spin_lock_irq(&call->recvmsg_queue.lock);

        __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)
                /* Change the state inside the lock so that recvmsg syncs
                 * correctly with it and using sendmsg() to send a reply
                 * doesn't race.
                 */
                rxrpc_end_rx_phase(call, sp->hdr.serial);

        spin_unlock_irq(&call->recvmsg_queue.lock);
}

/*
 * 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);

                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);
                }

                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, count = 1, stat_ix;

        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, &notify, &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;
                count++;
        }

        sp->offset = offset;
        sp->len    = len;
        rxrpc_input_data_one(call, skb, &notify, &ack_serial, &ack_reason);

        stat_ix = umin(count, ARRAY_SIZE(call->rxnet->stat_rx_jumbo)) - 1;
        atomic_inc(&call->rxnet->stat_rx_jumbo[stat_ix]);

        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 && !test_bit(RXRPC_CALL_CONN_CHALLENGING, &call->flags)) {
                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_ACK:
        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_call_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, 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, 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 = call->peer;
        unsigned int max_data, capacity;
        bool wake = false;
        u32 max_mtu     = ntohl(trailer->maxMTU);
        //u32 if_mtu    = ntohl(trailer->ifMTU);
        u32 rwind       = ntohl(trailer->rwind);
        u32 jumbo_max   = ntohl(trailer->jumbo_max);

        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;
        }

        max_mtu = clamp(max_mtu, 500, 65535);
        peer->ackr_max_data = max_mtu;

        if (max_mtu < peer->max_data) {
                trace_rxrpc_pmtud_reduce(peer, sp->hdr.serial, max_mtu,
                                         rxrpc_pmtud_reduce_ack);
                peer->max_data = max_mtu;
        }

        max_data = umin(max_mtu, peer->max_data);
        capacity = max_data;
        capacity += sizeof(struct rxrpc_jumbo_header); /* First subpacket has main hdr, not jumbo */
        capacity /= sizeof(struct rxrpc_jumbo_header) + RXRPC_JUMBO_DATALEN;

        if (jumbo_max == 0) {
                /* The peer says it supports pmtu discovery */
                peer->ackr_adv_pmtud = true;
        } else {
                peer->ackr_adv_pmtud = false;
                capacity = clamp(capacity, 1, jumbo_max);
        }

        call->tx_jumbo_max = capacity;

        if (wake)
                wake_up(&call->waitq);
}

#if defined(CONFIG_X86) && __GNUC__ && !defined(__clang__)
/* Clang doesn't support the %z constraint modifier */
#define shiftr_adv_rotr(shift_from, rotate_into) ({                     \
                        asm(" shr%z1 %1\n"                              \
                            " inc %0\n"                                 \
                            " rcr%z2 %2\n"                              \
                            : "+d"(shift_from), "+m"(*(shift_from)), "+rm"(rotate_into) \
                            );                                          \
                })
#else
#define shiftr_adv_rotr(shift_from, rotate_into) ({     \
                        typeof(rotate_into) __bit0 = *(shift_from) & 1; \
                        *(shift_from) >>= 1;                            \
                        shift_from++;                                   \
                        rotate_into >>= 1;                              \
                        rotate_into |= __bit0 << (sizeof(rotate_into) * 8 - 1); \
                })
#endif

/*
 * Deal with RTT samples from soft ACKs.
 */
static void rxrpc_input_soft_rtt(struct rxrpc_call *call,
                                 struct rxrpc_ack_summary *summary,
                                 struct rxrpc_txqueue *tq)
{
        for (int ix = 0; ix < RXRPC_NR_TXQUEUE; ix++)
                if (summary->acked_serial == tq->segment_serial[ix])
                        return rxrpc_add_data_rtt_sample(call, summary, tq, ix);
}

/*
 * Process a batch of soft ACKs specific to a transmission queue segment.
 */
static void rxrpc_input_soft_ack_tq(struct rxrpc_call *call,
                                    struct rxrpc_ack_summary *summary,
                                    struct rxrpc_txqueue *tq,
                                    unsigned long extracted_acks,
                                    int nr_reported,
                                    rxrpc_seq_t seq,
                                    rxrpc_seq_t *lowest_nak)
{
        unsigned long old_reported = 0, flipped, new_acks = 0;
        unsigned long a_to_n, n_to_a = 0;
        int new, a, n;

        if (tq->nr_reported_acks > 0)
                old_reported = ~0UL >> (RXRPC_NR_TXQUEUE - tq->nr_reported_acks);

        _enter("{%x,%lx,%d},%lx,%d,%x",
               tq->qbase, tq->segment_acked, tq->nr_reported_acks,
               extracted_acks, nr_reported, seq);

        _debug("[%x]", tq->qbase);
        _debug("tq    %16lx %u", tq->segment_acked, tq->nr_reported_acks);
        _debug("sack  %16lx %u", extracted_acks, nr_reported);

        /* See how many previously logged ACKs/NAKs have flipped. */
        flipped = (tq->segment_acked ^ extracted_acks) & old_reported;
        if (flipped) {
                n_to_a = ~tq->segment_acked & flipped; /* Old NAK -> ACK */
                a_to_n =  tq->segment_acked & flipped; /* Old ACK -> NAK */
                a = hweight_long(n_to_a);
                n = hweight_long(a_to_n);
                _debug("flip  %16lx", flipped);
                _debug("ntoa  %16lx %d", n_to_a, a);
                _debug("aton  %16lx %d", a_to_n, n);
                call->acks_nr_sacks     += a - n;
                call->acks_nr_snacks    += n - a;
                summary->nr_new_sacks   += a;
                summary->nr_new_snacks  += n;
        }

        /* See how many new ACKs/NAKs have been acquired. */
        new = nr_reported - tq->nr_reported_acks;
        if (new > 0) {
                new_acks = extracted_acks & ~old_reported;
                if (new_acks) {
                        a = hweight_long(new_acks);
                        n = new - a;
                        _debug("new_a %16lx new=%d a=%d n=%d", new_acks, new, a, n);
                        call->acks_nr_sacks     += a;
                        call->acks_nr_snacks    += n;
                        summary->nr_new_sacks   += a;
                        summary->nr_new_snacks  += n;
                } else {
                        call->acks_nr_snacks    += new;
                        summary->nr_new_snacks  += new;
                }
        }

        tq->nr_reported_acks = nr_reported;
        tq->segment_acked = extracted_acks;
        trace_rxrpc_apply_acks(call, tq);

        if (extracted_acks != ~0UL) {
                rxrpc_seq_t lowest = seq + ffz(extracted_acks);

                if (before(lowest, *lowest_nak))
                        *lowest_nak = lowest;
        }

        if (summary->acked_serial)
                rxrpc_input_soft_rtt(call, summary, tq);

        new_acks |= n_to_a;
        if (new_acks)
                rxrpc_input_rack(call, summary, tq, new_acks);

        if (call->tlp_serial &&
            rxrpc_seq_in_txq(tq, call->tlp_seq) &&
            test_bit(call->tlp_seq - tq->qbase, &new_acks))
                summary->tlp_probe_acked = true;
}

/*
 * 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)
{
        struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
        struct rxrpc_txqueue *tq = call->tx_queue;
        unsigned long extracted = ~0UL;
        unsigned int nr = 0, nsack;
        rxrpc_seq_t seq = call->acks_hard_ack + 1;
        rxrpc_seq_t lowest_nak = seq + sp->ack.nr_acks;
        u8 sack[256] __aligned(sizeof(unsigned long));
        u8 *acks = sack;

        _enter("%x,%x,%u", tq->qbase, seq, sp->ack.nr_acks);

        while (after(seq, tq->qbase + RXRPC_NR_TXQUEUE - 1))
                tq = tq->next;

        /* Extract an individual SACK table.  A normal SACK table is up to 255
         * bytes with 1 ACK flag per byte, but an extended SACK table can be up
         * to 256 bytes with up to 8 ACK/NACK flags per byte.  The ACK flags go
         * across all bit 0's then all bit 1's, then all bit 2's, ...
         */
        memset(sack, 0, sizeof(sack));
        nsack = umin(sp->ack.nr_acks, 256);
        if (skb_copy_bits(skb,
                          sizeof(struct rxrpc_wire_header) + sizeof(struct rxrpc_ackpacket),
                          sack, nsack) < 0)
                return;

        for (unsigned int i = 0; i < sp->ack.nr_acks; i++) {
                /* Decant ACKs until we hit a txqueue boundary. */
                if ((i & 255) == 0)
                        acks = sack;
                shiftr_adv_rotr(acks, extracted);
                seq++;
                nr++;
                if ((seq & RXRPC_TXQ_MASK) != 0)
                        continue;

                _debug("bound %16lx %u", extracted, nr);

                rxrpc_input_soft_ack_tq(call, summary, tq, extracted, RXRPC_NR_TXQUEUE,
                                        seq - RXRPC_NR_TXQUEUE, &lowest_nak);
                extracted = ~0UL;
                nr = 0;
                tq = tq->next;
                prefetch(tq);
        }

        if (nr) {
                unsigned int nr_reported = seq & RXRPC_TXQ_MASK;

                extracted >>= RXRPC_NR_TXQUEUE - nr_reported;
                _debug("tail  %16lx %u", extracted, nr_reported);
                rxrpc_input_soft_ack_tq(call, summary, tq, extracted, nr_reported,
                                        seq & ~RXRPC_TXQ_MASK, &lowest_nak);
        }

        /* 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 (lowest_nak != call->acks_lowest_nak) {
                call->acks_lowest_nak = lowest_nak;
                summary->new_low_snack = true;
        }

        _debug("summary A=%d+%d N=%d+%d",
               call->acks_nr_sacks,  summary->nr_new_sacks,
               call->acks_nr_snacks, summary->nr_new_snacks);
}

/*
 * 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 hard_ack, rxrpc_seq_t prev_pkt)
{
        rxrpc_seq_t base = READ_ONCE(call->acks_hard_ack);

        if (after(hard_ack, base))
                return true; /* The window advanced */

        if (before(hard_ack, 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(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_acktrailer trailer;
        struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
        rxrpc_seq_t first_soft_ack, hard_ack, prev_pkt;
        int nr_acks, offset, ioffset;

        _enter("");

        offset = sizeof(struct rxrpc_wire_header) + sizeof(struct rxrpc_ackpacket);

        summary.ack_serial      = sp->hdr.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.acked_serial    = sp->ack.acked_serial;
        summary.ack_reason      = (sp->ack.reason < RXRPC_ACK__INVALID ?
                                   sp->ack.reason : RXRPC_ACK__INVALID);

        trace_rxrpc_rx_ack(call, sp);
        rxrpc_inc_stat(call->rxnet, stat_rx_acks[summary.ack_reason]);
        prefetch(call->tx_queue);

        /* 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) &&
            hard_ack == 0 &&
            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) &&
            hard_ack == 0 &&
            prev_pkt == 0 &&
            call->tx_bottom == 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, hard_ack, prev_pkt)) {
                trace_rxrpc_rx_discard_ack(call, summary.ack_serial, hard_ack, prev_pkt);
                goto send_response; /* Still respond if requested. */
        }

        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);

        call->acks_latest_ts = ktime_get_real();
        call->acks_hard_ack = hard_ack;
        call->acks_prev_seq = prev_pkt;

        if (summary.acked_serial) {
                switch (summary.ack_reason) {
                case RXRPC_ACK_PING_RESPONSE:
                        rxrpc_complete_rtt_probe(call, call->acks_latest_ts,
                                                 summary.acked_serial, summary.ack_serial,
                                                 rxrpc_rtt_rx_ping_response);
                        break;
                default:
                        if (after(summary.acked_serial, call->acks_highest_serial))
                                call->acks_highest_serial = summary.acked_serial;
                        summary.rtt_sample_avail = true;
                        break;
                }
        }

        /* Parse rwind and mtu sizes if provided. */
        if (trailer.maxMTU)
                rxrpc_input_ack_trailer(call, skb, &trailer);

        if (hard_ack + 1 == 0)
                return rxrpc_proto_abort(call, 0, rxrpc_eproto_ackr_zero);

        /* Ignore ACKs unless we are transmitting or are waiting for
         * acknowledgement of the packets we've just been transmitting.
         */
        switch (__rxrpc_call_state(call)) {
        case RXRPC_CALL_CLIENT_SEND_REQUEST:
        case RXRPC_CALL_CLIENT_AWAIT_ACK:
        case RXRPC_CALL_SERVER_SEND_REPLY:
        case RXRPC_CALL_SERVER_AWAIT_ACK:
                break;
        default:
                goto send_response;
        }

        if (before(hard_ack, call->tx_bottom) ||
            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->tx_bottom)) {
                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);
        }

        if (test_bit(RXRPC_CALL_TX_LAST, &call->flags) &&
            call->acks_nr_sacks == call->tx_top - hard_ack &&
            rxrpc_is_client_call(call))
                rxrpc_propose_ping(call, summary.ack_serial,
                                   rxrpc_propose_ack_ping_for_lost_reply);

        /* Drive the congestion management algorithm first and then RACK-TLP as
         * the latter depends on the state/change in state in the former.
         */
        rxrpc_congestion_management(call, &summary);
        rxrpc_rack_detect_loss_and_arm_timer(call, &summary);
        rxrpc_tlp_process_ack(call, &summary);
        if (call->tlp_serial && after_eq(summary.acked_serial, call->tlp_serial))
                call->tlp_serial = 0;

send_response:
        if (summary.ack_reason == RXRPC_ACK_PING)
                rxrpc_send_ACK(call, RXRPC_ACK_PING_RESPONSE, summary.ack_serial,
                               rxrpc_propose_ack_respond_to_ping);
        else if (sp->hdr.flags & RXRPC_REQUEST_ACK)
                rxrpc_send_ACK(call, RXRPC_ACK_REQUESTED, summary.ack_serial,
                               rxrpc_propose_ack_respond_to_ack);
}

/*
 * Process an ACKALL packet.
 */
static void rxrpc_input_ackall(struct rxrpc_call *call, struct sk_buff *skb)
{
        struct rxrpc_ack_summary summary = { 0 };

        switch (__rxrpc_call_state(call)) {
        case RXRPC_CALL_CLIENT_SEND_REQUEST:
        case RXRPC_CALL_CLIENT_AWAIT_ACK:
        case RXRPC_CALL_SERVER_SEND_REPLY:
        case RXRPC_CALL_SERVER_AWAIT_ACK:
                break;
        default:
                return;
        }

        if (rxrpc_rotate_tx_window(call, call->tx_transmitted, &summary))
                rxrpc_end_tx_phase(call, false, rxrpc_eproto_unexpected_ackall);
}

/*
 * Process an ABORT packet directed at a call.
 */
static void rxrpc_input_abort(struct rxrpc_call *call, struct sk_buff *skb)
{
        struct rxrpc_skb_priv *sp = rxrpc_skb(skb);

        trace_rxrpc_rx_abort(call, sp->hdr.serial, skb->priority);

        rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
                                  skb->priority, -ECONNABORTED);
}

/*
 * Process an incoming call packet.
 */
void rxrpc_input_call_packet(struct rxrpc_call *call, struct sk_buff *skb)
{
        struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
        unsigned long timo;

        _enter("%p,%p", call, skb);

        if (sp->hdr.serviceId != call->dest_srx.srx_service)
                call->dest_srx.srx_service = sp->hdr.serviceId;
        if ((int)sp->hdr.serial - (int)call->rx_serial > 0)
                call->rx_serial = sp->hdr.serial;
        if (!test_bit(RXRPC_CALL_RX_HEARD, &call->flags))
                set_bit(RXRPC_CALL_RX_HEARD, &call->flags);

        timo = READ_ONCE(call->next_rx_timo);
        if (timo) {
                ktime_t delay = ms_to_ktime(timo);

                call->expect_rx_by = ktime_add(ktime_get_real(), delay);
                trace_rxrpc_timer_set(call, delay, rxrpc_timer_trace_expect_rx);
        }

        switch (sp->hdr.type) {
        case RXRPC_PACKET_TYPE_DATA:
                return rxrpc_input_data(call, skb);

        case RXRPC_PACKET_TYPE_ACK:
                return rxrpc_input_ack(call, skb);

        case RXRPC_PACKET_TYPE_BUSY:
                /* Just ignore BUSY packets from the server; the retry and
                 * lifespan timers will take care of business.  BUSY packets
                 * from the client don't make sense.
                 */
                return;

        case RXRPC_PACKET_TYPE_ABORT:
                return rxrpc_input_abort(call, skb);

        case RXRPC_PACKET_TYPE_ACKALL:
                return rxrpc_input_ackall(call, skb);

        default:
                break;
        }
}

/*
 * Handle a new service call on a channel implicitly completing the preceding
 * call on that channel.  This does not apply to client conns.
 *
 * TODO: If callNumber > call_id + 1, renegotiate security.
 */
void rxrpc_implicit_end_call(struct rxrpc_call *call, struct sk_buff *skb)
{
        switch (__rxrpc_call_state(call)) {
        case RXRPC_CALL_SERVER_AWAIT_ACK:
                rxrpc_call_completed(call);
                fallthrough;
        case RXRPC_CALL_COMPLETE:
                break;
        default:
                rxrpc_abort_call(call, 0, RX_CALL_DEAD, -ESHUTDOWN,
                                 rxrpc_eproto_improper_term);
                trace_rxrpc_improper_term(call);
                break;
        }

        rxrpc_input_call_event(call);
}