From: Eric Dumazet Date: Thu, 16 Apr 2026 20:03:15 +0000 (+0000) Subject: tcp: annotate data-races around tp->reord_seen X-Git-Tag: v7.1-rc1~36^2~60^2~4 X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=62585690e6b2a112c408fe25f142b246ac833c42;p=thirdparty%2Fkernel%2Flinux.git tcp: annotate data-races around tp->reord_seen tcp_get_timestamping_opt_stats() intentionally runs lockless, we must add READ_ONCE() and WRITE_ONCE() annotations to keep KCSAN happy. Fixes: 7ec65372ca53 ("tcp: add stat of data packet reordering events") Signed-off-by: Eric Dumazet Link: https://patch.msgid.link/20260416200319.3608680-11-edumazet@google.com Signed-off-by: Jakub Kicinski --- diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 57c4dcc8bfe9..39a4b06e36bb 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -4466,7 +4466,7 @@ struct sk_buff *tcp_get_timestamping_opt_stats(const struct sock *sk, nla_put_u64_64bit(stats, TCP_NLA_BYTES_RETRANS, READ_ONCE(tp->bytes_retrans), TCP_NLA_PAD); nla_put_u32(stats, TCP_NLA_DSACK_DUPS, READ_ONCE(tp->dsack_dups)); - nla_put_u32(stats, TCP_NLA_REORD_SEEN, tp->reord_seen); + nla_put_u32(stats, TCP_NLA_REORD_SEEN, READ_ONCE(tp->reord_seen)); nla_put_u32(stats, TCP_NLA_SRTT, tp->srtt_us >> 3); nla_put_u16(stats, TCP_NLA_TIMEOUT_REHASH, tp->timeout_rehash); nla_put_u32(stats, TCP_NLA_BYTES_NOTSENT, diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 65b3ecc6be4b..896a5a5a6b1a 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -1299,7 +1299,7 @@ static void tcp_check_sack_reordering(struct sock *sk, const u32 low_seq, } /* This exciting event is worth to be remembered. 8) */ - tp->reord_seen++; + WRITE_ONCE(tp->reord_seen, tp->reord_seen + 1); NET_INC_STATS(sock_net(sk), ts ? LINUX_MIB_TCPTSREORDER : LINUX_MIB_TCPSACKREORDER); } @@ -2443,7 +2443,7 @@ static void tcp_check_reno_reordering(struct sock *sk, const int addend) WRITE_ONCE(tp->reordering, min_t(u32, tp->packets_out + addend, READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_max_reordering))); - tp->reord_seen++; + WRITE_ONCE(tp->reord_seen, tp->reord_seen + 1); NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPRENOREORDER); }