From: David Laight <david.laight.linux@gmail.com>
To: quanyeyang <quanyeyang@proton.me>
Cc: Quanye Yang via B4 Relay
<devnull+quanyeyang.proton.me@kernel.org>,
Eric Dumazet <edumazet@google.com>,
Neal Cardwell <ncardwell@google.com>,
Kuniyuki Iwashima <kuniyu@google.com>,
"David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Simon Horman <horms@kernel.org>,
"Matthieu Baerts (NGI0)" <matttbe@kernel.org>,
Geliang Tang <geliang@kernel.org>,
Mat Martineau <martineau@kernel.org>,
Jiayuan Chen <jiayuan.chen@linux.dev>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next v4 1/2] tcp: annotate lockless access to sk->sk_err
Date: Fri, 18 Sep 2026 13:27:47 +0100 [thread overview]
Message-ID: <20260918132747.6ac8beeb@pumpkin> (raw)
In-Reply-To: <zEvCcu9s6PbTRajtbCvCik2zCOJsXozLWWvYsLfl6AV4IJLyXmS63i5nuaCmqk_5DsRajMO3IjRtFpOSpmRY55ByjpBJ8NmtwDk-kSpr9bM=@proton.me>
On Fri, 18 Sep 2026 10:33:04 +0000
quanyeyang <quanyeyang@proton.me> wrote:
> On Friday, September 18th, 2026 at AM 2:51, David Laight <david.laight.linux@gmail.com> wrote:
>
> > Don't they need annotating with data_race() ?
>
> I think READ_ONCE() is the intended marker here.
If the race is with locked accesses I think you need both.
David
>
> These loads are part of the I/O control flow (stop send/recv/splice),
> not diagnostic or heuristic reads. data_race() would silence KCSAN
> but would not restrict compiler optimizations, so the load could still
> be torn, fused or reissued. READ_ONCE() is a single-copy atomic load
> and pairs with the existing WRITE_ONCE()/xchg() updates of sk_err,
> same as tcp_poll() after e13ec3da05d1.
>
> sock_error() uses data_race() only on the fast-path "is it zero?"
> check, which is then validated by xchg(). That pattern does not
> apply to these peeks.
>
> Quanye
>
next prev parent reply other threads:[~2026-09-18 12:27 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-17 13:41 [PATCH net-next v4 0/2] tcp: annotate lockless access to sk->sk_err Quanye Yang
2026-09-17 13:41 ` Quanye Yang via B4 Relay
2026-09-17 13:41 ` [PATCH net-next v4 1/2] " Quanye Yang
2026-09-17 13:41 ` Quanye Yang via B4 Relay
2026-09-18 9:51 ` David Laight
2026-09-18 10:33 ` quanyeyang
2026-09-18 12:27 ` David Laight [this message]
2026-09-18 14:49 ` quanyeyang
2026-09-21 14:10 ` netdev-bot+sashiko
2026-09-25 4:31 ` quanyeyang
2026-09-24 15:10 ` Jakub Kicinski
2026-09-17 13:41 ` [PATCH net-next v4 2/2] mptcp: " Quanye Yang
2026-09-17 13:41 ` Quanye Yang via B4 Relay
2026-09-18 11:28 ` Matthieu Baerts
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