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tcp: record last received ipv6 flowlabel 

In order to better estimate whether a data packet has been
retransmitted or is the result of a TLP, we save the last received
ipv6 flowlabel.

To make space for this field we resize the "ato" field in
inet_connection_sock as the current value of TCP_DELACK_MAX can be
fully contained in 8 bits and add a compile_time_assert ensuring this
field is the required size.

v2: addressed kernel bot feedback about dccp_delack_timer()
v3: addressed build error introduced by commit bbf80d713f ("tcp:
derive delack_max from rto_min")

Signed-off-by: David Morley <morleyd@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Tested-by: David Morley <morleyd@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
David Morley 2023-10-06 01:18:40 +00:00 committed by Paolo Abeni
parent 8cea95b0bd
commit 95b9a87c6a
6 changed files with 26 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
include/net/inet_connection_sock.h
View File

@ -114,7 +114,10 @@ struct inet_connection_sock {
__u8 quick; /* Scheduled number of quick acks */
__u8 pingpong; /* The session is interactive */
__u8 retry; /* Number of attempts */
__u32 ato; /* Predicted tick of soft clock */
#define ATO_BITS 8
__u32 ato:ATO_BITS, /* Predicted tick of soft clock */
lrcv_flowlabel:20, /* last received ipv6 flowlabel */
unused:4;
unsigned long timeout; /* Currently scheduled timeout */
__u32 lrcvtime; /* timestamp of last received data packet */
__u16 last_seg_size; /* Size of last incoming segment */

2
include/net/tcp.h
View File

@ -131,6 +131,8 @@ void tcp_time_wait(struct sock *sk, int state, int timeo);
#define TCP_FIN_TIMEOUT_MAX (120 * HZ) /* max TCP_LINGER2 value (two minutes) */
#define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
static_assert((1 << ATO_BITS) > TCP_DELACK_MAX);
#if HZ >= 100
#define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
#define TCP_ATO_MIN ((unsigned)(HZ/25))

4
net/dccp/timer.c
View File

@ -196,8 +196,8 @@ static void dccp_delack_timer(struct timer_list *t)
if (inet_csk_ack_scheduled(sk)) {
if (!inet_csk_in_pingpong_mode(sk)) {
/* Delayed ACK missed: inflate ATO. */
icsk->icsk_ack.ato = min(icsk->icsk_ack.ato << 1,
icsk->icsk_rto);
icsk->icsk_ack.ato = min_t(u32, icsk->icsk_ack.ato << 1,
icsk->icsk_rto);
} else {
/* Delayed ACK missed: leave pingpong mode and
* deflate ATO.

4
net/ipv4/tcp.c
View File

@ -3756,8 +3756,8 @@ void tcp_get_info(struct sock *sk, struct tcp_info *info)
info->tcpi_options |= TCPI_OPT_SYN_DATA;
info->tcpi_rto = jiffies_to_usecs(icsk->icsk_rto);
info->tcpi_ato = jiffies_to_usecs(min(icsk->icsk_ack.ato,
tcp_delack_max(sk)));
info->tcpi_ato = jiffies_to_usecs(min_t(u32, icsk->icsk_ack.ato,
tcp_delack_max(sk)));
info->tcpi_snd_mss = tp->mss_cache;
info->tcpi_rcv_mss = icsk->icsk_ack.rcv_mss;

15
net/ipv4/tcp_input.c
View File

@ -778,6 +778,16 @@ new_measure:
tp->rcvq_space.time = tp->tcp_mstamp;
}
static void tcp_save_lrcv_flowlabel(struct sock *sk, const struct sk_buff *skb)
{
#if IS_ENABLED(CONFIG_IPV6)
struct inet_connection_sock *icsk = inet_csk(sk);
if (skb->protocol == htons(ETH_P_IPV6))
icsk->icsk_ack.lrcv_flowlabel = ntohl(ip6_flowlabel(ipv6_hdr(skb)));
#endif
}
/* There is something which you must keep in mind when you analyze the
* behavior of the tp->ato delayed ack timeout interval. When a
* connection starts up, we want to ack as quickly as possible. The
@ -826,6 +836,7 @@ static void tcp_event_data_recv(struct sock *sk, struct sk_buff *skb)
}
}
icsk->icsk_ack.lrcvtime = now;
tcp_save_lrcv_flowlabel(sk, skb);
tcp_ecn_check_ce(sk, skb);
@ -4519,6 +4530,9 @@ static void tcp_rcv_spurious_retrans(struct sock *sk, const struct sk_buff *skb)
if (TCP_SKB_CB(skb)->seq == tcp_sk(sk)->duplicate_sack[0].start_seq &&
sk_rethink_txhash(sk))
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPDUPLICATEDATAREHASH);
/* Save last flowlabel after a spurious retrans. */
tcp_save_lrcv_flowlabel(sk, skb);
}
static void tcp_send_dupack(struct sock *sk, const struct sk_buff *skb)
@ -4835,6 +4849,7 @@ static void tcp_data_queue_ofo(struct sock *sk, struct sk_buff *skb)
u32 seq, end_seq;
bool fragstolen;
tcp_save_lrcv_flowlabel(sk, skb);
tcp_ecn_check_ce(sk, skb);
if (unlikely(tcp_try_rmem_schedule(sk, skb, skb->truesize))) {

2
net/ipv4/tcp_timer.c
View File

@ -322,7 +322,7 @@ void tcp_delack_timer_handler(struct sock *sk)
if (inet_csk_ack_scheduled(sk)) {
if (!inet_csk_in_pingpong_mode(sk)) {
/* Delayed ACK missed: inflate ATO. */
icsk->icsk_ack.ato = min(icsk->icsk_ack.ato << 1, icsk->icsk_rto);
icsk->icsk_ack.ato = min_t(u32, icsk->icsk_ack.ato << 1, icsk->icsk_rto);
} else {
/* Delayed ACK missed: leave pingpong mode and
* deflate ATO.