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Commit 21c325d0 authored by Eric Dumazet's avatar Eric Dumazet Committed by Greg Kroah-Hartman
Browse files

tcp: annotate data-races around tp->notsent_lowat 



[ Upstream commit 1aeb87bc1440c5447a7fa2d6e3c2cca52cbd206b ]

tp->notsent_lowat can be read locklessly from do_tcp_getsockopt()
and tcp_poll().

Fixes: c9bee3b7 ("tcp: TCP_NOTSENT_LOWAT socket option")
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20230719212857.3943972-10-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 7175277b

include/net/tcp.h

+5 −1
Original line number Diff line number Diff line
@@ -1953,7 +1953,11 @@ void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr); 
static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp)

{

	struct net *net = sock_net((struct sock *)tp);

	return tp->notsent_lowat ?: READ_ONCE(net->ipv4.sysctl_tcp_notsent_lowat);

	u32 val;



	val = READ_ONCE(tp->notsent_lowat);



	return val ?: READ_ONCE(net->ipv4.sysctl_tcp_notsent_lowat);

}



/* @wake is one when sk_stream_write_space() calls us.

net/ipv4/tcp.c

+2 −2
Original line number Diff line number Diff line
@@ -3165,7 +3165,7 @@ static int do_tcp_setsockopt(struct sock *sk, int level, 
		err = tcp_repair_set_window(tp, optval, optlen);

		break;

	case TCP_NOTSENT_LOWAT:

		tp->notsent_lowat = val;

		WRITE_ONCE(tp->notsent_lowat, val);

		sk->sk_write_space(sk);

		break;

	case TCP_INQ:
@@ -3642,7 +3642,7 @@ static int do_tcp_getsockopt(struct sock *sk, int level, 
		val = tcp_time_stamp_raw() + tp->tsoffset;

		break;

	case TCP_NOTSENT_LOWAT:

		val = tp->notsent_lowat;

		val = READ_ONCE(tp->notsent_lowat);

		break;

	case TCP_INQ:

		val = tp->recvmsg_inq;