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Date: Fri, 29 Sep 2023 21:03:51 +0000
From: David Morley <morleyd.kernel@...il.com>
To: David Miller <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>
Cc: netdev@...r.kernel.org,
David Morley <morleyd@...gle.com>,
Neal Cardwell <ncardwell@...gle.com>,
Yuchung Cheng <ycheng@...gle.com>
Subject: [PATCH net-next v2 1/2] tcp: record last received ipv6 flowlabel
From: David Morley <morleyd@...gle.com>
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()
Signed-off-by: David Morley <morleyd@...gle.com>
Signed-off-by: Neal Cardwell <ncardwell@...gle.com>
Signed-off-by: Yuchung Cheng <ycheng@...gle.com>
Tested-by: David Morley <morleyd@...gle.com>
Reviewed-by: Eric Dumazet <edumazet@...gle.com>
---
include/net/inet_connection_sock.h | 5 ++++-
include/net/tcp.h | 2 ++
net/dccp/timer.c | 4 ++--
net/ipv4/tcp_input.c | 15 +++++++++++++++
net/ipv4/tcp_timer.c | 2 +-
5 files changed, 24 insertions(+), 4 deletions(-)
diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
index 5d2fcc137b88..d6d9d1c1985a 100644
--- a/include/net/inet_connection_sock.h
+++ b/include/net/inet_connection_sock.h
@@ -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 */
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 91688d0dadcd..61fe664d109b 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -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))
diff --git a/net/dccp/timer.c b/net/dccp/timer.c
index b3255e87cc7e..a4cfb47b60e5 100644
--- a/net/dccp/timer.c
+++ b/net/dccp/timer.c
@@ -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.
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 584825ddd0a0..abe7494361c0 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -765,6 +765,16 @@ void tcp_rcv_space_adjust(struct sock *sk)
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
@@ -813,6 +823,7 @@ 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);
@@ -4506,6 +4517,9 @@ 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)
@@ -4822,6 +4836,7 @@ 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))) {
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 3f61c6a70a1f..0862b73dd3b5 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -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.
--
2.42.0.582.g8ccd20d70d-goog
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