[PATCH net 07/14] tcp: annotate data-races around tp->bytes_sent

[Eric Dumazet <edumazet@google.com>]

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

Fixes: ba113c3aa79a ("tcp: add data bytes sent stats")
Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 net/ipv4/tcp.c        | 2 +-
 net/ipv4/tcp_output.c | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 729936d13a5c6d9c39edc880636e01cf0973688e..f999b86851cdcc2a9b9ce379397e55293871c00a 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -4461,7 +4461,7 @@ struct sk_buff *tcp_get_timestamping_opt_stats(const struct sock *sk,
 			  READ_ONCE(tp->write_seq) - READ_ONCE(tp->snd_una)));
 	nla_put_u8(stats, TCP_NLA_CA_STATE, inet_csk(sk)->icsk_ca_state);
 
-	nla_put_u64_64bit(stats, TCP_NLA_BYTES_SENT, tp->bytes_sent,
+	nla_put_u64_64bit(stats, TCP_NLA_BYTES_SENT, READ_ONCE(tp->bytes_sent),
 			  TCP_NLA_PAD);
 	nla_put_u64_64bit(stats, TCP_NLA_BYTES_RETRANS, tp->bytes_retrans,
 			  TCP_NLA_PAD);
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 9f83c7e4acabc64f0a45e4879c326694a306b368..87af4731df87ea5f310d39b1392cb995d4fa8f78 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1690,7 +1690,8 @@ static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb,
 		tcp_event_data_sent(tp, sk);
 		WRITE_ONCE(tp->data_segs_out,
 			   tp->data_segs_out + tcp_skb_pcount(skb));
-		tp->bytes_sent += skb->len - tcp_header_size;
+		WRITE_ONCE(tp->bytes_sent,
+			   tp->bytes_sent + skb->len - tcp_header_size);
 	}
 
 	if (after(tcb->end_seq, tp->snd_nxt) || tcb->seq == tcb->end_seq)
-- 
2.54.0.rc1.513.gad8abe7a5a-goog