![David Howells](/assets/img/avatar_default.png)
Keep that call timeouts as ktimes rather than jiffies so that they can be expressed as functions of RTT. Signed-off-by: David Howells <dhowells@redhat.com>
363 lines
9.6 KiB
C
363 lines
9.6 KiB
C
/* 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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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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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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* Set the timer
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*/
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void rxrpc_set_timer(struct rxrpc_call *call, enum rxrpc_timer_trace why,
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ktime_t now)
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{
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unsigned long t_j, now_j = jiffies;
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ktime_t t;
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read_lock_bh(&call->state_lock);
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if (call->state < RXRPC_CALL_COMPLETE) {
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t = call->expire_at;
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if (!ktime_after(t, now))
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goto out;
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if (ktime_after(call->resend_at, now) &&
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ktime_before(call->resend_at, t))
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t = call->resend_at;
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if (ktime_after(call->ack_at, now) &&
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ktime_before(call->ack_at, t))
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t = call->ack_at;
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t_j = nsecs_to_jiffies(ktime_to_ns(ktime_sub(t, now)));
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t_j += jiffies;
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/* We have to make sure that the calculated jiffies value falls
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* at or after the nsec value, or we may loop ceaselessly
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* because the timer times out, but we haven't reached the nsec
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* timeout yet.
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*/
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t_j++;
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if (call->timer.expires != t_j || !timer_pending(&call->timer)) {
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mod_timer(&call->timer, t_j);
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trace_rxrpc_timer(call, why, now, now_j);
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}
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}
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out:
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read_unlock_bh(&call->state_lock);
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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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u16 skew, u32 serial, bool immediate,
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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 int expiry = rxrpc_soft_ack_delay;
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ktime_t now, ack_at;
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s8 prior = rxrpc_ack_priority[ack_reason];
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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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call->ackr_skew = skew;
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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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call->ackr_skew = skew;
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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_PING:
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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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now = ktime_get_real();
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ack_at = ktime_add_ms(now, expiry);
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if (ktime_before(ack_at, call->ack_at)) {
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call->ack_at = ack_at;
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rxrpc_set_timer(call, rxrpc_timer_set_for_ack, now);
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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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u16 skew, 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, skew, 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, ktime_t now)
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{
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struct rxrpc_skb_priv *sp;
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struct sk_buff *skb;
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rxrpc_seq_t cursor, seq, top;
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ktime_t max_age, oldest, ack_ts;
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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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max_age = ktime_sub_ms(now, rxrpc_resend_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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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_tx_seen);
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sp = rxrpc_skb(skb);
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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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call->resend_at = ktime_add_ms(oldest, rxrpc_resend_timeout);
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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_set_timer(call, rxrpc_timer_set_for_resend, now);
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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, 0, true, false,
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rxrpc_propose_ack_ping_for_lost_ack);
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rxrpc_send_call_packet(call, RXRPC_PACKET_TYPE_ACK);
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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_tx_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_tx_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_tx_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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ktime_t now;
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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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if (test_and_clear_bit(RXRPC_CALL_EV_ABORT, &call->events)) {
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rxrpc_send_call_packet(call, RXRPC_PACKET_TYPE_ABORT);
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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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goto out_put;
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}
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now = ktime_get_real();
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if (ktime_before(call->expire_at, now)) {
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rxrpc_abort_call("EXP", call, 0, RX_CALL_TIMEOUT, ETIME);
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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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if (test_and_clear_bit(RXRPC_CALL_EV_ACK, &call->events) ||
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ktime_before(call->ack_at, now)) {
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call->ack_at = call->expire_at;
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if (call->ackr_reason) {
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rxrpc_send_call_packet(call, RXRPC_PACKET_TYPE_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_RESEND, &call->events) ||
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ktime_before(call->resend_at, now)) {
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rxrpc_resend(call, now);
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goto recheck_state;
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}
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rxrpc_set_timer(call, rxrpc_timer_set_for_resend, now);
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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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__rxrpc_queue_call(call);
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goto out;
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}
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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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}
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