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Message-ID: <178b9f2dbb3c56fcfef46a97ea395bdd13ebfb59.camel@redhat.com>
Subject: Re: [PATCH v3] tcp: add support for SO_PEEK_OFF
From: Paolo Abeni <pabeni@redhat.com>
To: Jon Maloy <jmaloy@redhat.com>, Eric Dumazet <edumazet@google.com>
Date: Thu, 15 Feb 2024 18:41:17 +0100
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On Thu, 2024-02-15 at 10:11 -0500, Jon Maloy wrote:
> I wonder if the following could be acceptable:
>=20
> =C2=A0if (flags & MSG_PEEK)
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 sk_peek_offset_fwd(sk, used);
> =C2=A0else if (peek_offset > 0)
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 sk_peek_offset_bwd(sk, used);
>=20
> =C2=A0peek_offset is already present in the data cache, and if it has the=
value
> =C2=A0zero it means either that that sk->sk_peek_off is unused (-1) or ac=
tually is zero.
> =C2=A0Either way, no rewind is needed in that case.
I agree the above should avoid touching cold cachelines in the
fastpath, and looks functionally correct to me.
The last word is up to Eric :)
Cheers,
Paolo