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Date: Wed, 10 Nov 2021 09:53:13 +0100
From: Florian Westphal <fw@strlen.de>
To: Paolo Abeni <pabeni@redhat.com>
Cc: Florian Westphal <fw@strlen.de>, mptcp@lists.linux.dev
Subject: Re: [PATCH mptcp-next 3/3] mptcp: add SIOCINQ, OUTQ and OUTQNSD
 ioctls
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Paolo Abeni <pabeni@redhat.com> wrote:
> > +	if (sk->sk_state == TCP_LISTEN)
> > +		return -EINVAL;
> > +
> > +	if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
> > +		return 0;
> > +
> > +	delta = READ_ONCE(msk->write_seq) - v;
> 
> This is under the msk socket lock and write_seq is protected by the
> full/plain msk socket lock so READ_ONCE should not be necessary, I
> think. The same for 'snd_nxt' below. 

Then why is write_seq updated with WRITE_ONCE in lots of places?