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tcp: add data-races annotations around tp->reordering, tp->snd_cwnd

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tcp_get_timestamping_opt_stats() intentionally runs lockless, we must
add READ_ONCE(), WRITE_ONCE() data_race() annotations to keep KCSAN happy.

Fixes: bb7c19f960 ("tcp: add related fields into SCM_TIMESTAMPING_OPT_STATS")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260416200319.3608680-4-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2026-04-16 20:03:08 +00:00 committed by Jakub Kicinski
parent 21e92a38cf
commit 829ba1f329
4 changed files with 14 additions and 12 deletions
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2
include/net/tcp.h
View File

@ -1513,7 +1513,7 @@ static inline u32 tcp_snd_cwnd(const struct tcp_sock *tp)
static inline void tcp_snd_cwnd_set(struct tcp_sock *tp, u32 val)
{
WARN_ON_ONCE((int)val <= 0);
tp->snd_cwnd = val;
WRITE_ONCE(tp->snd_cwnd, val);
}
static inline bool tcp_in_slow_start(const struct tcp_sock *tp)

8
net/ipv4/tcp.c
View File

@ -4445,13 +4445,13 @@ struct sk_buff *tcp_get_timestamping_opt_stats(const struct sock *sk,
rate64 = tcp_compute_delivery_rate(tp);
nla_put_u64_64bit(stats, TCP_NLA_DELIVERY_RATE, rate64, TCP_NLA_PAD);
nla_put_u32(stats, TCP_NLA_SND_CWND, tcp_snd_cwnd(tp));
nla_put_u32(stats, TCP_NLA_REORDERING, tp->reordering);
nla_put_u32(stats, TCP_NLA_MIN_RTT, tcp_min_rtt(tp));
nla_put_u32(stats, TCP_NLA_SND_CWND, READ_ONCE(tp->snd_cwnd));
nla_put_u32(stats, TCP_NLA_REORDERING, READ_ONCE(tp->reordering));
nla_put_u32(stats, TCP_NLA_MIN_RTT, data_race(tcp_min_rtt(tp)));
nla_put_u8(stats, TCP_NLA_RECUR_RETRANS,
READ_ONCE(inet_csk(sk)->icsk_retransmits));
nla_put_u8(stats, TCP_NLA_DELIVERY_RATE_APP_LMT, !!tp->rate_app_limited);
nla_put_u8(stats, TCP_NLA_DELIVERY_RATE_APP_LMT, data_race(!!tp->rate_app_limited));
nla_put_u32(stats, TCP_NLA_SND_SSTHRESH, tp->snd_ssthresh);
nla_put_u32(stats, TCP_NLA_DELIVERED, tp->delivered);
nla_put_u32(stats, TCP_NLA_DELIVERED_CE, tp->delivered_ce);

14
net/ipv4/tcp_input.c
View File

@ -1293,8 +1293,9 @@ static void tcp_check_sack_reordering(struct sock *sk, const u32 low_seq,
tp->sacked_out,
tp->undo_marker ? tp->undo_retrans : 0);
#endif
tp->reordering = min_t(u32, (metric + mss - 1) / mss,
READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_max_reordering));
WRITE_ONCE(tp->reordering,
min_t(u32, (metric + mss - 1) / mss,
READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_max_reordering)));
}
/* This exciting event is worth to be remembered. 8) */
@ -2439,8 +2440,9 @@ static void tcp_check_reno_reordering(struct sock *sk, const int addend)
if (!tcp_limit_reno_sacked(tp))
return;
tp->reordering = min_t(u32, tp->packets_out + addend,
READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_max_reordering));
WRITE_ONCE(tp->reordering,
min_t(u32, tp->packets_out + addend,
READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_max_reordering)));
tp->reord_seen++;
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPRENOREORDER);
}
@ -2579,8 +2581,8 @@ void tcp_enter_loss(struct sock *sk)
reordering = READ_ONCE(net->ipv4.sysctl_tcp_reordering);
if (icsk->icsk_ca_state <= TCP_CA_Disorder &&
tp->sacked_out >= reordering)
tp->reordering = min_t(unsigned int, tp->reordering,
reordering);
WRITE_ONCE(tp->reordering,
min_t(unsigned int, tp->reordering, reordering));
tcp_set_ca_state(sk, TCP_CA_Loss);
tp->high_seq = tp->snd_nxt;

2
net/ipv4/tcp_metrics.c
View File

@ -496,7 +496,7 @@ void tcp_init_metrics(struct sock *sk)
}
val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
if (val && tp->reordering != val)
tp->reordering = val;
WRITE_ONCE(tp->reordering, val);
crtt = tcp_metric_get(tm, TCP_METRIC_RTT);
rcu_read_unlock();