mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-12-11 21:14:07 +08:00
02c28dffb1
Commit2ad6691d98
, which moved the modification of the status annotation for a packet in the Tx buffer prior to the retransmission moved the state clearance, but managed to lose the bit that set it to UNACK. Consequently, if a retransmission occurs, the packet is accidentally changed to the ACK state (ie. 0) by masking it off, which means that the packet isn't counted towards the tally of newly-ACK'd packets if it gets hard-ACK'd. This then prevents the congestion control algorithm from recovering properly. Fix by reinstating the change of state to UNACK. Spotted by the generic/460 xfstest. Fixes:2ad6691d98
("rxrpc: Fix race between incoming ACK parser and retransmitter") Signed-off-by: David Howells <dhowells@redhat.com>
449 lines
12 KiB
C
449 lines
12 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
|
|
/* Management of Tx window, Tx resend, ACKs and out-of-sequence reception
|
|
*
|
|
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
|
|
* Written by David Howells (dhowells@redhat.com)
|
|
*/
|
|
|
|
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
|
|
|
|
#include <linux/module.h>
|
|
#include <linux/circ_buf.h>
|
|
#include <linux/net.h>
|
|
#include <linux/skbuff.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/udp.h>
|
|
#include <net/sock.h>
|
|
#include <net/af_rxrpc.h>
|
|
#include "ar-internal.h"
|
|
|
|
/*
|
|
* Propose a PING ACK be sent.
|
|
*/
|
|
static void rxrpc_propose_ping(struct rxrpc_call *call,
|
|
bool immediate, bool background)
|
|
{
|
|
if (immediate) {
|
|
if (background &&
|
|
!test_and_set_bit(RXRPC_CALL_EV_PING, &call->events))
|
|
rxrpc_queue_call(call);
|
|
} else {
|
|
unsigned long now = jiffies;
|
|
unsigned long ping_at = now + rxrpc_idle_ack_delay;
|
|
|
|
if (time_before(ping_at, call->ping_at)) {
|
|
WRITE_ONCE(call->ping_at, ping_at);
|
|
rxrpc_reduce_call_timer(call, ping_at, now,
|
|
rxrpc_timer_set_for_ping);
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* propose an ACK be sent
|
|
*/
|
|
static void __rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
|
|
u32 serial, bool immediate, bool background,
|
|
enum rxrpc_propose_ack_trace why)
|
|
{
|
|
enum rxrpc_propose_ack_outcome outcome = rxrpc_propose_ack_use;
|
|
unsigned long expiry = rxrpc_soft_ack_delay;
|
|
s8 prior = rxrpc_ack_priority[ack_reason];
|
|
|
|
/* Pings are handled specially because we don't want to accidentally
|
|
* lose a ping response by subsuming it into a ping.
|
|
*/
|
|
if (ack_reason == RXRPC_ACK_PING) {
|
|
rxrpc_propose_ping(call, immediate, background);
|
|
goto trace;
|
|
}
|
|
|
|
/* Update DELAY, IDLE, REQUESTED and PING_RESPONSE ACK serial
|
|
* numbers, but we don't alter the timeout.
|
|
*/
|
|
_debug("prior %u %u vs %u %u",
|
|
ack_reason, prior,
|
|
call->ackr_reason, rxrpc_ack_priority[call->ackr_reason]);
|
|
if (ack_reason == call->ackr_reason) {
|
|
if (RXRPC_ACK_UPDATEABLE & (1 << ack_reason)) {
|
|
outcome = rxrpc_propose_ack_update;
|
|
call->ackr_serial = serial;
|
|
}
|
|
if (!immediate)
|
|
goto trace;
|
|
} else if (prior > rxrpc_ack_priority[call->ackr_reason]) {
|
|
call->ackr_reason = ack_reason;
|
|
call->ackr_serial = serial;
|
|
} else {
|
|
outcome = rxrpc_propose_ack_subsume;
|
|
}
|
|
|
|
switch (ack_reason) {
|
|
case RXRPC_ACK_REQUESTED:
|
|
if (rxrpc_requested_ack_delay < expiry)
|
|
expiry = rxrpc_requested_ack_delay;
|
|
if (serial == 1)
|
|
immediate = false;
|
|
break;
|
|
|
|
case RXRPC_ACK_DELAY:
|
|
if (rxrpc_soft_ack_delay < expiry)
|
|
expiry = rxrpc_soft_ack_delay;
|
|
break;
|
|
|
|
case RXRPC_ACK_IDLE:
|
|
if (rxrpc_idle_ack_delay < expiry)
|
|
expiry = rxrpc_idle_ack_delay;
|
|
break;
|
|
|
|
default:
|
|
immediate = true;
|
|
break;
|
|
}
|
|
|
|
if (test_bit(RXRPC_CALL_EV_ACK, &call->events)) {
|
|
_debug("already scheduled");
|
|
} else if (immediate || expiry == 0) {
|
|
_debug("immediate ACK %lx", call->events);
|
|
if (!test_and_set_bit(RXRPC_CALL_EV_ACK, &call->events) &&
|
|
background)
|
|
rxrpc_queue_call(call);
|
|
} else {
|
|
unsigned long now = jiffies, ack_at;
|
|
|
|
if (call->peer->srtt_us != 0)
|
|
ack_at = usecs_to_jiffies(call->peer->srtt_us >> 3);
|
|
else
|
|
ack_at = expiry;
|
|
|
|
ack_at += READ_ONCE(call->tx_backoff);
|
|
ack_at += now;
|
|
if (time_before(ack_at, call->ack_at)) {
|
|
WRITE_ONCE(call->ack_at, ack_at);
|
|
rxrpc_reduce_call_timer(call, ack_at, now,
|
|
rxrpc_timer_set_for_ack);
|
|
}
|
|
}
|
|
|
|
trace:
|
|
trace_rxrpc_propose_ack(call, why, ack_reason, serial, immediate,
|
|
background, outcome);
|
|
}
|
|
|
|
/*
|
|
* propose an ACK be sent, locking the call structure
|
|
*/
|
|
void rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
|
|
u32 serial, bool immediate, bool background,
|
|
enum rxrpc_propose_ack_trace why)
|
|
{
|
|
spin_lock_bh(&call->lock);
|
|
__rxrpc_propose_ACK(call, ack_reason, serial,
|
|
immediate, background, why);
|
|
spin_unlock_bh(&call->lock);
|
|
}
|
|
|
|
/*
|
|
* Handle congestion being detected by the retransmit timeout.
|
|
*/
|
|
static void rxrpc_congestion_timeout(struct rxrpc_call *call)
|
|
{
|
|
set_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags);
|
|
}
|
|
|
|
/*
|
|
* Perform retransmission of NAK'd and unack'd packets.
|
|
*/
|
|
static void rxrpc_resend(struct rxrpc_call *call, unsigned long now_j)
|
|
{
|
|
struct sk_buff *skb;
|
|
unsigned long resend_at, rto_j;
|
|
rxrpc_seq_t cursor, seq, top;
|
|
ktime_t now, max_age, oldest, ack_ts;
|
|
int ix;
|
|
u8 annotation, anno_type, retrans = 0, unacked = 0;
|
|
|
|
_enter("{%d,%d}", call->tx_hard_ack, call->tx_top);
|
|
|
|
rto_j = call->peer->rto_j;
|
|
|
|
now = ktime_get_real();
|
|
max_age = ktime_sub(now, jiffies_to_usecs(rto_j));
|
|
|
|
spin_lock_bh(&call->lock);
|
|
|
|
cursor = call->tx_hard_ack;
|
|
top = call->tx_top;
|
|
ASSERT(before_eq(cursor, top));
|
|
if (cursor == top)
|
|
goto out_unlock;
|
|
|
|
/* Scan the packet list without dropping the lock and decide which of
|
|
* the packets in the Tx buffer we're going to resend and what the new
|
|
* resend timeout will be.
|
|
*/
|
|
trace_rxrpc_resend(call, (cursor + 1) & RXRPC_RXTX_BUFF_MASK);
|
|
oldest = now;
|
|
for (seq = cursor + 1; before_eq(seq, top); seq++) {
|
|
ix = seq & RXRPC_RXTX_BUFF_MASK;
|
|
annotation = call->rxtx_annotations[ix];
|
|
anno_type = annotation & RXRPC_TX_ANNO_MASK;
|
|
annotation &= ~RXRPC_TX_ANNO_MASK;
|
|
if (anno_type == RXRPC_TX_ANNO_ACK)
|
|
continue;
|
|
|
|
skb = call->rxtx_buffer[ix];
|
|
rxrpc_see_skb(skb, rxrpc_skb_seen);
|
|
|
|
if (anno_type == RXRPC_TX_ANNO_UNACK) {
|
|
if (ktime_after(skb->tstamp, max_age)) {
|
|
if (ktime_before(skb->tstamp, oldest))
|
|
oldest = skb->tstamp;
|
|
continue;
|
|
}
|
|
if (!(annotation & RXRPC_TX_ANNO_RESENT))
|
|
unacked++;
|
|
}
|
|
|
|
/* Okay, we need to retransmit a packet. */
|
|
call->rxtx_annotations[ix] = RXRPC_TX_ANNO_RETRANS | annotation;
|
|
retrans++;
|
|
trace_rxrpc_retransmit(call, seq, annotation | anno_type,
|
|
ktime_to_ns(ktime_sub(skb->tstamp, max_age)));
|
|
}
|
|
|
|
resend_at = nsecs_to_jiffies(ktime_to_ns(ktime_sub(now, oldest)));
|
|
resend_at += jiffies + rto_j;
|
|
WRITE_ONCE(call->resend_at, resend_at);
|
|
|
|
if (unacked)
|
|
rxrpc_congestion_timeout(call);
|
|
|
|
/* If there was nothing that needed retransmission then it's likely
|
|
* that an ACK got lost somewhere. Send a ping to find out instead of
|
|
* retransmitting data.
|
|
*/
|
|
if (!retrans) {
|
|
rxrpc_reduce_call_timer(call, resend_at, now_j,
|
|
rxrpc_timer_set_for_resend);
|
|
spin_unlock_bh(&call->lock);
|
|
ack_ts = ktime_sub(now, call->acks_latest_ts);
|
|
if (ktime_to_us(ack_ts) < (call->peer->srtt_us >> 3))
|
|
goto out;
|
|
rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, true, false,
|
|
rxrpc_propose_ack_ping_for_lost_ack);
|
|
rxrpc_send_ack_packet(call, true, NULL);
|
|
goto out;
|
|
}
|
|
|
|
/* Now go through the Tx window and perform the retransmissions. We
|
|
* have to drop the lock for each send. If an ACK comes in whilst the
|
|
* lock is dropped, it may clear some of the retransmission markers for
|
|
* packets that it soft-ACKs.
|
|
*/
|
|
for (seq = cursor + 1; before_eq(seq, top); seq++) {
|
|
ix = seq & RXRPC_RXTX_BUFF_MASK;
|
|
annotation = call->rxtx_annotations[ix];
|
|
anno_type = annotation & RXRPC_TX_ANNO_MASK;
|
|
if (anno_type != RXRPC_TX_ANNO_RETRANS)
|
|
continue;
|
|
|
|
/* We need to reset the retransmission state, but we need to do
|
|
* so before we drop the lock as a new ACK/NAK may come in and
|
|
* confuse things
|
|
*/
|
|
annotation &= ~RXRPC_TX_ANNO_MASK;
|
|
annotation |= RXRPC_TX_ANNO_UNACK | RXRPC_TX_ANNO_RESENT;
|
|
call->rxtx_annotations[ix] = annotation;
|
|
|
|
skb = call->rxtx_buffer[ix];
|
|
if (!skb)
|
|
continue;
|
|
|
|
rxrpc_get_skb(skb, rxrpc_skb_got);
|
|
spin_unlock_bh(&call->lock);
|
|
|
|
if (rxrpc_send_data_packet(call, skb, true) < 0) {
|
|
rxrpc_free_skb(skb, rxrpc_skb_freed);
|
|
return;
|
|
}
|
|
|
|
if (rxrpc_is_client_call(call))
|
|
rxrpc_expose_client_call(call);
|
|
|
|
rxrpc_free_skb(skb, rxrpc_skb_freed);
|
|
spin_lock_bh(&call->lock);
|
|
if (after(call->tx_hard_ack, seq))
|
|
seq = call->tx_hard_ack;
|
|
}
|
|
|
|
out_unlock:
|
|
spin_unlock_bh(&call->lock);
|
|
out:
|
|
_leave("");
|
|
}
|
|
|
|
/*
|
|
* Handle retransmission and deferred ACK/abort generation.
|
|
*/
|
|
void rxrpc_process_call(struct work_struct *work)
|
|
{
|
|
struct rxrpc_call *call =
|
|
container_of(work, struct rxrpc_call, processor);
|
|
rxrpc_serial_t *send_ack;
|
|
unsigned long now, next, t;
|
|
unsigned int iterations = 0;
|
|
|
|
rxrpc_see_call(call);
|
|
|
|
//printk("\n--------------------\n");
|
|
_enter("{%d,%s,%lx}",
|
|
call->debug_id, rxrpc_call_states[call->state], call->events);
|
|
|
|
recheck_state:
|
|
/* Limit the number of times we do this before returning to the manager */
|
|
iterations++;
|
|
if (iterations > 5)
|
|
goto requeue;
|
|
|
|
if (test_and_clear_bit(RXRPC_CALL_EV_ABORT, &call->events)) {
|
|
rxrpc_send_abort_packet(call);
|
|
goto recheck_state;
|
|
}
|
|
|
|
if (call->state == RXRPC_CALL_COMPLETE) {
|
|
del_timer_sync(&call->timer);
|
|
goto out_put;
|
|
}
|
|
|
|
/* Work out if any timeouts tripped */
|
|
now = jiffies;
|
|
t = READ_ONCE(call->expect_rx_by);
|
|
if (time_after_eq(now, t)) {
|
|
trace_rxrpc_timer(call, rxrpc_timer_exp_normal, now);
|
|
set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
|
|
}
|
|
|
|
t = READ_ONCE(call->expect_req_by);
|
|
if (call->state == RXRPC_CALL_SERVER_RECV_REQUEST &&
|
|
time_after_eq(now, t)) {
|
|
trace_rxrpc_timer(call, rxrpc_timer_exp_idle, now);
|
|
set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
|
|
}
|
|
|
|
t = READ_ONCE(call->expect_term_by);
|
|
if (time_after_eq(now, t)) {
|
|
trace_rxrpc_timer(call, rxrpc_timer_exp_hard, now);
|
|
set_bit(RXRPC_CALL_EV_EXPIRED, &call->events);
|
|
}
|
|
|
|
t = READ_ONCE(call->ack_at);
|
|
if (time_after_eq(now, t)) {
|
|
trace_rxrpc_timer(call, rxrpc_timer_exp_ack, now);
|
|
cmpxchg(&call->ack_at, t, now + MAX_JIFFY_OFFSET);
|
|
set_bit(RXRPC_CALL_EV_ACK, &call->events);
|
|
}
|
|
|
|
t = READ_ONCE(call->ack_lost_at);
|
|
if (time_after_eq(now, t)) {
|
|
trace_rxrpc_timer(call, rxrpc_timer_exp_lost_ack, now);
|
|
cmpxchg(&call->ack_lost_at, t, now + MAX_JIFFY_OFFSET);
|
|
set_bit(RXRPC_CALL_EV_ACK_LOST, &call->events);
|
|
}
|
|
|
|
t = READ_ONCE(call->keepalive_at);
|
|
if (time_after_eq(now, t)) {
|
|
trace_rxrpc_timer(call, rxrpc_timer_exp_keepalive, now);
|
|
cmpxchg(&call->keepalive_at, t, now + MAX_JIFFY_OFFSET);
|
|
rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, true, true,
|
|
rxrpc_propose_ack_ping_for_keepalive);
|
|
set_bit(RXRPC_CALL_EV_PING, &call->events);
|
|
}
|
|
|
|
t = READ_ONCE(call->ping_at);
|
|
if (time_after_eq(now, t)) {
|
|
trace_rxrpc_timer(call, rxrpc_timer_exp_ping, now);
|
|
cmpxchg(&call->ping_at, t, now + MAX_JIFFY_OFFSET);
|
|
set_bit(RXRPC_CALL_EV_PING, &call->events);
|
|
}
|
|
|
|
t = READ_ONCE(call->resend_at);
|
|
if (time_after_eq(now, t)) {
|
|
trace_rxrpc_timer(call, rxrpc_timer_exp_resend, now);
|
|
cmpxchg(&call->resend_at, t, now + MAX_JIFFY_OFFSET);
|
|
set_bit(RXRPC_CALL_EV_RESEND, &call->events);
|
|
}
|
|
|
|
/* Process events */
|
|
if (test_and_clear_bit(RXRPC_CALL_EV_EXPIRED, &call->events)) {
|
|
if (test_bit(RXRPC_CALL_RX_HEARD, &call->flags) &&
|
|
(int)call->conn->hi_serial - (int)call->rx_serial > 0) {
|
|
trace_rxrpc_call_reset(call);
|
|
rxrpc_abort_call("EXP", call, 0, RX_USER_ABORT, -ECONNRESET);
|
|
} else {
|
|
rxrpc_abort_call("EXP", call, 0, RX_USER_ABORT, -ETIME);
|
|
}
|
|
set_bit(RXRPC_CALL_EV_ABORT, &call->events);
|
|
goto recheck_state;
|
|
}
|
|
|
|
send_ack = NULL;
|
|
if (test_and_clear_bit(RXRPC_CALL_EV_ACK_LOST, &call->events)) {
|
|
call->acks_lost_top = call->tx_top;
|
|
rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, true, false,
|
|
rxrpc_propose_ack_ping_for_lost_ack);
|
|
send_ack = &call->acks_lost_ping;
|
|
}
|
|
|
|
if (test_and_clear_bit(RXRPC_CALL_EV_ACK, &call->events) ||
|
|
send_ack) {
|
|
if (call->ackr_reason) {
|
|
rxrpc_send_ack_packet(call, false, send_ack);
|
|
goto recheck_state;
|
|
}
|
|
}
|
|
|
|
if (test_and_clear_bit(RXRPC_CALL_EV_PING, &call->events)) {
|
|
rxrpc_send_ack_packet(call, true, NULL);
|
|
goto recheck_state;
|
|
}
|
|
|
|
if (test_and_clear_bit(RXRPC_CALL_EV_RESEND, &call->events)) {
|
|
rxrpc_resend(call, now);
|
|
goto recheck_state;
|
|
}
|
|
|
|
/* Make sure the timer is restarted */
|
|
next = call->expect_rx_by;
|
|
|
|
#define set(T) { t = READ_ONCE(T); if (time_before(t, next)) next = t; }
|
|
|
|
set(call->expect_req_by);
|
|
set(call->expect_term_by);
|
|
set(call->ack_at);
|
|
set(call->ack_lost_at);
|
|
set(call->resend_at);
|
|
set(call->keepalive_at);
|
|
set(call->ping_at);
|
|
|
|
now = jiffies;
|
|
if (time_after_eq(now, next))
|
|
goto recheck_state;
|
|
|
|
rxrpc_reduce_call_timer(call, next, now, rxrpc_timer_restart);
|
|
|
|
/* other events may have been raised since we started checking */
|
|
if (call->events && call->state < RXRPC_CALL_COMPLETE)
|
|
goto requeue;
|
|
|
|
out_put:
|
|
rxrpc_put_call(call, rxrpc_call_put);
|
|
out:
|
|
_leave("");
|
|
return;
|
|
|
|
requeue:
|
|
__rxrpc_queue_call(call);
|
|
goto out;
|
|
}
|