![David Howells](/assets/img/avatar_default.png)
Use the previously-added transmit-phase skbuff private flag to simplify the socket buffer tracing a bit. Which phase the skbuff comes from can now be divined from the skb rather than having to be guessed from the call state. We can also reduce the number of rxrpc_skb_trace values by eliminating the difference between Tx and Rx in the symbols. Signed-off-by: David Howells <dhowells@redhat.com>
463 lines
13 KiB
C
463 lines
13 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* Management of Tx window, Tx resend, ACKs and out-of-sequence reception
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*
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* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/circ_buf.h>
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#include <linux/net.h>
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#include <linux/skbuff.h>
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#include <linux/slab.h>
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#include <linux/udp.h>
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#include <net/sock.h>
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#include <net/af_rxrpc.h>
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#include "ar-internal.h"
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/*
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* Propose a PING ACK be sent.
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*/
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static void rxrpc_propose_ping(struct rxrpc_call *call,
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bool immediate, bool background)
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{
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if (immediate) {
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if (background &&
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!test_and_set_bit(RXRPC_CALL_EV_PING, &call->events))
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rxrpc_queue_call(call);
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} else {
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unsigned long now = jiffies;
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unsigned long ping_at = now + rxrpc_idle_ack_delay;
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if (time_before(ping_at, call->ping_at)) {
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WRITE_ONCE(call->ping_at, ping_at);
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rxrpc_reduce_call_timer(call, ping_at, now,
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rxrpc_timer_set_for_ping);
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}
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}
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}
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/*
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* propose an ACK be sent
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*/
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static void __rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
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u32 serial, bool immediate, bool background,
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enum rxrpc_propose_ack_trace why)
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{
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enum rxrpc_propose_ack_outcome outcome = rxrpc_propose_ack_use;
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unsigned long expiry = rxrpc_soft_ack_delay;
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s8 prior = rxrpc_ack_priority[ack_reason];
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/* Pings are handled specially because we don't want to accidentally
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* lose a ping response by subsuming it into a ping.
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*/
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if (ack_reason == RXRPC_ACK_PING) {
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rxrpc_propose_ping(call, immediate, background);
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goto trace;
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}
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/* Update DELAY, IDLE, REQUESTED and PING_RESPONSE ACK serial
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* numbers, but we don't alter the timeout.
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*/
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_debug("prior %u %u vs %u %u",
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ack_reason, prior,
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call->ackr_reason, rxrpc_ack_priority[call->ackr_reason]);
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if (ack_reason == call->ackr_reason) {
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if (RXRPC_ACK_UPDATEABLE & (1 << ack_reason)) {
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outcome = rxrpc_propose_ack_update;
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call->ackr_serial = serial;
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}
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if (!immediate)
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goto trace;
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} else if (prior > rxrpc_ack_priority[call->ackr_reason]) {
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call->ackr_reason = ack_reason;
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call->ackr_serial = serial;
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} else {
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outcome = rxrpc_propose_ack_subsume;
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}
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switch (ack_reason) {
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case RXRPC_ACK_REQUESTED:
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if (rxrpc_requested_ack_delay < expiry)
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expiry = rxrpc_requested_ack_delay;
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if (serial == 1)
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immediate = false;
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break;
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case RXRPC_ACK_DELAY:
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if (rxrpc_soft_ack_delay < expiry)
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expiry = rxrpc_soft_ack_delay;
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break;
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case RXRPC_ACK_IDLE:
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if (rxrpc_idle_ack_delay < expiry)
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expiry = rxrpc_idle_ack_delay;
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break;
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default:
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immediate = true;
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break;
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}
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if (test_bit(RXRPC_CALL_EV_ACK, &call->events)) {
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_debug("already scheduled");
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} else if (immediate || expiry == 0) {
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_debug("immediate ACK %lx", call->events);
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if (!test_and_set_bit(RXRPC_CALL_EV_ACK, &call->events) &&
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background)
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rxrpc_queue_call(call);
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} else {
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unsigned long now = jiffies, ack_at;
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if (call->peer->rtt_usage > 0)
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ack_at = nsecs_to_jiffies(call->peer->rtt);
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else
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ack_at = expiry;
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ack_at += READ_ONCE(call->tx_backoff);
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ack_at += now;
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if (time_before(ack_at, call->ack_at)) {
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WRITE_ONCE(call->ack_at, ack_at);
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rxrpc_reduce_call_timer(call, ack_at, now,
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rxrpc_timer_set_for_ack);
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}
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}
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trace:
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trace_rxrpc_propose_ack(call, why, ack_reason, serial, immediate,
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background, outcome);
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}
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/*
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* propose an ACK be sent, locking the call structure
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*/
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void rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
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u32 serial, bool immediate, bool background,
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enum rxrpc_propose_ack_trace why)
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{
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spin_lock_bh(&call->lock);
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__rxrpc_propose_ACK(call, ack_reason, serial,
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immediate, background, why);
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spin_unlock_bh(&call->lock);
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}
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/*
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* Handle congestion being detected by the retransmit timeout.
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*/
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static void rxrpc_congestion_timeout(struct rxrpc_call *call)
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{
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set_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags);
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}
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/*
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* Perform retransmission of NAK'd and unack'd packets.
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*/
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static void rxrpc_resend(struct rxrpc_call *call, unsigned long now_j)
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{
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struct sk_buff *skb;
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unsigned long resend_at;
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rxrpc_seq_t cursor, seq, top;
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ktime_t now, max_age, oldest, ack_ts, timeout, min_timeo;
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int ix;
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u8 annotation, anno_type, retrans = 0, unacked = 0;
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_enter("{%d,%d}", call->tx_hard_ack, call->tx_top);
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if (call->peer->rtt_usage > 1)
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timeout = ns_to_ktime(call->peer->rtt * 3 / 2);
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else
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timeout = ms_to_ktime(rxrpc_resend_timeout);
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min_timeo = ns_to_ktime((1000000000 / HZ) * 4);
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if (ktime_before(timeout, min_timeo))
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timeout = min_timeo;
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now = ktime_get_real();
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max_age = ktime_sub(now, timeout);
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spin_lock_bh(&call->lock);
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cursor = call->tx_hard_ack;
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top = call->tx_top;
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ASSERT(before_eq(cursor, top));
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if (cursor == top)
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goto out_unlock;
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/* Scan the packet list without dropping the lock and decide which of
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* the packets in the Tx buffer we're going to resend and what the new
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* resend timeout will be.
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*/
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trace_rxrpc_resend(call, (cursor + 1) & RXRPC_RXTX_BUFF_MASK);
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oldest = now;
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for (seq = cursor + 1; before_eq(seq, top); seq++) {
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ix = seq & RXRPC_RXTX_BUFF_MASK;
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annotation = call->rxtx_annotations[ix];
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anno_type = annotation & RXRPC_TX_ANNO_MASK;
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annotation &= ~RXRPC_TX_ANNO_MASK;
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if (anno_type == RXRPC_TX_ANNO_ACK)
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continue;
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skb = call->rxtx_buffer[ix];
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rxrpc_see_skb(skb, rxrpc_skb_seen);
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if (anno_type == RXRPC_TX_ANNO_UNACK) {
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if (ktime_after(skb->tstamp, max_age)) {
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if (ktime_before(skb->tstamp, oldest))
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oldest = skb->tstamp;
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continue;
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}
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if (!(annotation & RXRPC_TX_ANNO_RESENT))
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unacked++;
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}
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/* Okay, we need to retransmit a packet. */
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call->rxtx_annotations[ix] = RXRPC_TX_ANNO_RETRANS | annotation;
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retrans++;
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trace_rxrpc_retransmit(call, seq, annotation | anno_type,
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ktime_to_ns(ktime_sub(skb->tstamp, max_age)));
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}
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resend_at = nsecs_to_jiffies(ktime_to_ns(ktime_sub(now, oldest)));
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resend_at += jiffies + rxrpc_resend_timeout;
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WRITE_ONCE(call->resend_at, resend_at);
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if (unacked)
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rxrpc_congestion_timeout(call);
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/* If there was nothing that needed retransmission then it's likely
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* that an ACK got lost somewhere. Send a ping to find out instead of
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* retransmitting data.
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*/
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if (!retrans) {
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rxrpc_reduce_call_timer(call, resend_at, now_j,
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rxrpc_timer_set_for_resend);
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spin_unlock_bh(&call->lock);
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ack_ts = ktime_sub(now, call->acks_latest_ts);
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if (ktime_to_ns(ack_ts) < call->peer->rtt)
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goto out;
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rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, true, false,
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rxrpc_propose_ack_ping_for_lost_ack);
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rxrpc_send_ack_packet(call, true, NULL);
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goto out;
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}
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/* Now go through the Tx window and perform the retransmissions. We
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* have to drop the lock for each send. If an ACK comes in whilst the
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* lock is dropped, it may clear some of the retransmission markers for
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* packets that it soft-ACKs.
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*/
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for (seq = cursor + 1; before_eq(seq, top); seq++) {
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ix = seq & RXRPC_RXTX_BUFF_MASK;
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annotation = call->rxtx_annotations[ix];
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anno_type = annotation & RXRPC_TX_ANNO_MASK;
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if (anno_type != RXRPC_TX_ANNO_RETRANS)
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continue;
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skb = call->rxtx_buffer[ix];
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rxrpc_get_skb(skb, rxrpc_skb_got);
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spin_unlock_bh(&call->lock);
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if (rxrpc_send_data_packet(call, skb, true) < 0) {
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rxrpc_free_skb(skb, rxrpc_skb_freed);
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return;
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}
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if (rxrpc_is_client_call(call))
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rxrpc_expose_client_call(call);
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rxrpc_free_skb(skb, rxrpc_skb_freed);
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spin_lock_bh(&call->lock);
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/* We need to clear the retransmit state, but there are two
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* things we need to be aware of: A new ACK/NAK might have been
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* received and the packet might have been hard-ACK'd (in which
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* case it will no longer be in the buffer).
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*/
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if (after(seq, call->tx_hard_ack)) {
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annotation = call->rxtx_annotations[ix];
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anno_type = annotation & RXRPC_TX_ANNO_MASK;
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if (anno_type == RXRPC_TX_ANNO_RETRANS ||
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anno_type == RXRPC_TX_ANNO_NAK) {
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annotation &= ~RXRPC_TX_ANNO_MASK;
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annotation |= RXRPC_TX_ANNO_UNACK;
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}
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annotation |= RXRPC_TX_ANNO_RESENT;
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call->rxtx_annotations[ix] = annotation;
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}
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if (after(call->tx_hard_ack, seq))
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seq = call->tx_hard_ack;
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}
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out_unlock:
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spin_unlock_bh(&call->lock);
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out:
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_leave("");
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}
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/*
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* Handle retransmission and deferred ACK/abort generation.
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*/
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void rxrpc_process_call(struct work_struct *work)
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{
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struct rxrpc_call *call =
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container_of(work, struct rxrpc_call, processor);
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rxrpc_serial_t *send_ack;
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unsigned long now, next, t;
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unsigned int iterations = 0;
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rxrpc_see_call(call);
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//printk("\n--------------------\n");
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_enter("{%d,%s,%lx}",
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call->debug_id, rxrpc_call_states[call->state], call->events);
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recheck_state:
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/* Limit the number of times we do this before returning to the manager */
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iterations++;
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if (iterations > 5)
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goto requeue;
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if (test_and_clear_bit(RXRPC_CALL_EV_ABORT, &call->events)) {
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rxrpc_send_abort_packet(call);
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goto recheck_state;
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}
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if (call->state == RXRPC_CALL_COMPLETE) {
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del_timer_sync(&call->timer);
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rxrpc_notify_socket(call);
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goto out_put;
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}
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/* Work out if any timeouts tripped */
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now = jiffies;
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t = READ_ONCE(call->expect_rx_by);
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if (time_after_eq(now, t)) {
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trace_rxrpc_timer(call, rxrpc_timer_exp_normal, now);
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set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
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}
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t = READ_ONCE(call->expect_req_by);
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if (call->state == RXRPC_CALL_SERVER_RECV_REQUEST &&
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time_after_eq(now, t)) {
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trace_rxrpc_timer(call, rxrpc_timer_exp_idle, now);
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set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
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}
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t = READ_ONCE(call->expect_term_by);
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if (time_after_eq(now, t)) {
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trace_rxrpc_timer(call, rxrpc_timer_exp_hard, now);
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set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
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}
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t = READ_ONCE(call->ack_at);
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if (time_after_eq(now, t)) {
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trace_rxrpc_timer(call, rxrpc_timer_exp_ack, now);
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cmpxchg(&call->ack_at, t, now + MAX_JIFFY_OFFSET);
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set_bit(RXRPC_CALL_EV_ACK, &call->events);
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}
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t = READ_ONCE(call->ack_lost_at);
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if (time_after_eq(now, t)) {
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trace_rxrpc_timer(call, rxrpc_timer_exp_lost_ack, now);
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cmpxchg(&call->ack_lost_at, t, now + MAX_JIFFY_OFFSET);
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set_bit(RXRPC_CALL_EV_ACK_LOST, &call->events);
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}
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t = READ_ONCE(call->keepalive_at);
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if (time_after_eq(now, t)) {
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trace_rxrpc_timer(call, rxrpc_timer_exp_keepalive, now);
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cmpxchg(&call->keepalive_at, t, now + MAX_JIFFY_OFFSET);
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rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, true, true,
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rxrpc_propose_ack_ping_for_keepalive);
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set_bit(RXRPC_CALL_EV_PING, &call->events);
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}
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t = READ_ONCE(call->ping_at);
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if (time_after_eq(now, t)) {
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trace_rxrpc_timer(call, rxrpc_timer_exp_ping, now);
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cmpxchg(&call->ping_at, t, now + MAX_JIFFY_OFFSET);
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set_bit(RXRPC_CALL_EV_PING, &call->events);
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}
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t = READ_ONCE(call->resend_at);
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if (time_after_eq(now, t)) {
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trace_rxrpc_timer(call, rxrpc_timer_exp_resend, now);
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cmpxchg(&call->resend_at, t, now + MAX_JIFFY_OFFSET);
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set_bit(RXRPC_CALL_EV_RESEND, &call->events);
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}
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/* Process events */
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if (test_and_clear_bit(RXRPC_CALL_EV_EXPIRED, &call->events)) {
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if (test_bit(RXRPC_CALL_RX_HEARD, &call->flags) &&
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(int)call->conn->hi_serial - (int)call->rx_serial > 0) {
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trace_rxrpc_call_reset(call);
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rxrpc_abort_call("EXP", call, 0, RX_USER_ABORT, -ECONNRESET);
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} else {
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rxrpc_abort_call("EXP", call, 0, RX_USER_ABORT, -ETIME);
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}
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set_bit(RXRPC_CALL_EV_ABORT, &call->events);
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goto recheck_state;
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}
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send_ack = NULL;
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if (test_and_clear_bit(RXRPC_CALL_EV_ACK_LOST, &call->events)) {
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call->acks_lost_top = call->tx_top;
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rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, true, false,
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rxrpc_propose_ack_ping_for_lost_ack);
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send_ack = &call->acks_lost_ping;
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}
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if (test_and_clear_bit(RXRPC_CALL_EV_ACK, &call->events) ||
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send_ack) {
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if (call->ackr_reason) {
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rxrpc_send_ack_packet(call, false, send_ack);
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goto recheck_state;
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}
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}
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if (test_and_clear_bit(RXRPC_CALL_EV_PING, &call->events)) {
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rxrpc_send_ack_packet(call, true, NULL);
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goto recheck_state;
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}
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if (test_and_clear_bit(RXRPC_CALL_EV_RESEND, &call->events)) {
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rxrpc_resend(call, now);
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goto recheck_state;
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}
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/* Make sure the timer is restarted */
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next = call->expect_rx_by;
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#define set(T) { t = READ_ONCE(T); if (time_before(t, next)) next = t; }
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set(call->expect_req_by);
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set(call->expect_term_by);
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set(call->ack_at);
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set(call->ack_lost_at);
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set(call->resend_at);
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set(call->keepalive_at);
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set(call->ping_at);
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now = jiffies;
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if (time_after_eq(now, next))
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goto recheck_state;
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rxrpc_reduce_call_timer(call, next, now, rxrpc_timer_restart);
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/* other events may have been raised since we started checking */
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if (call->events && call->state < RXRPC_CALL_COMPLETE)
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goto requeue;
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out_put:
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rxrpc_put_call(call, rxrpc_call_put);
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out:
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_leave("");
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return;
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requeue:
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__rxrpc_queue_call(call);
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goto out;
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}
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