From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: passt.top; dmarc=none (p=none dis=none) header.from=gibson.dropbear.id.au Authentication-Results: passt.top; dkim=pass (2048-bit key; secure) header.d=gibson.dropbear.id.au header.i=@gibson.dropbear.id.au header.a=rsa-sha256 header.s=202412 header.b=CCmHnzpi; dkim-atps=neutral Received: from mail.ozlabs.org (gandalf.ozlabs.org [150.107.74.76]) by passt.top (Postfix) with ESMTPS id 01F3F5A061F for ; Thu, 30 Jan 2025 01:53:23 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gibson.dropbear.id.au; s=202412; t=1738198384; bh=rgOKo6v1H6wRQKPA2HBlUQ+CCH+n/jmVGKwD8PmO8A4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=CCmHnzpiDFOTzORfIdgUj8VUE5eRO5Xnu2to25tMW+INPtO/o0w+zk1d4Y97qaoZZ UWqWcHD2E4BKevJgGGLcqjFRNJ4PwPl7Ll0ZnTMnXn1h+8p8koC8DQEqME4snMwF6v UMUyloPTGemkxLfS4fp9nQdK0SZz/AWe4wvgwqPsrnkvWcmElvW9qdpNm1MwKE191E p+kiys+120ayS7+vZ3BN9VdE0DJwSVRsTnujW77Eoy6hO2pfYDisDd0t9n/ytiyRS0 kdCO8XGTx9oWKT3SdvhIbto5rG9Jfi+k8x74L8XQdkqAO/6wpRUylNyjYb5zIkx2TH 83D0SRTuhxPGQ== Received: by gandalf.ozlabs.org (Postfix, from userid 1007) id 4Yk0r02hK2z4x5m; Thu, 30 Jan 2025 11:53:04 +1100 (AEDT) Date: Thu, 30 Jan 2025 11:44:19 +1100 From: David Gibson To: Stefano Brivio Subject: Re: [PATCH 3/7] tcp_conn: Avoid 7-bit hole in struct tcp_splice_conn Message-ID: References: <20250127231532.672363-1-sbrivio@redhat.com> <20250127231532.672363-4-sbrivio@redhat.com> <20250128074833.716e4a66@elisabeth> <20250129083340.38926745@elisabeth> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="X3tr89nPxP1841zT" Content-Disposition: inline In-Reply-To: <20250129083340.38926745@elisabeth> Message-ID-Hash: MVIKDRKD3VLZZMX7DMRRPHAEQS67HWRS X-Message-ID-Hash: MVIKDRKD3VLZZMX7DMRRPHAEQS67HWRS X-MailFrom: dgibson@gandalf.ozlabs.org X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: passt-dev@passt.top, Laurent Vivier X-Mailman-Version: 3.3.8 Precedence: list List-Id: Development discussion and patches for passt Archived-At: Archived-At: List-Archive: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: --X3tr89nPxP1841zT Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jan 29, 2025 at 08:33:40AM +0100, Stefano Brivio wrote: > On Wed, 29 Jan 2025 12:02:09 +1100 > David Gibson wrote: >=20 > > On Tue, Jan 28, 2025 at 07:48:33AM +0100, Stefano Brivio wrote: > > > On Tue, 28 Jan 2025 11:53:09 +1100 > > > David Gibson wrote: > > > =20 > > > > On Tue, Jan 28, 2025 at 12:15:28AM +0100, Stefano Brivio wrote: =20 > > > > > Moving in_epoll out of the common flow data created a 7-bit hole = in > > > > > struct tcp_splice_conn: repack by shrinking @flags by one (otherw= ise > > > > > unused) bit. =20 > > > >=20 > > > > Is this actually necessary for the migration stuff? Or just a clea= nup > > > > you spotted along the way? =20 > > >=20 > > > I thought it was helpful to keep the same size on 32-bit, but it looks > > > like it's not actually needed. > > >=20 > > > Let me drop it from this series as it's just noise and I'm trying to > > > keep this slim. If we are all happy with it I can apply it. If not I'= ll > > > forget about it. =20 > >=20 > > Eh, I don't care that much either way. > >=20 > > Note, btw, that bit-field packing is another way source and > > destination could potentially have mismatching data structures. IIUC > > bit field packing is described by the ABI and doesn't necessarily > > match the byte endianness. >=20 > Right, that's actually the reason that brought me to this change: I was > comparing stuff between x86_64 and armv6l. On the other hand, this part > of the specific ABI is generally considered stable so I can rely on it. Uhh.. a specific ABI is stable, yes, but IIUC the whole point of these endian, word size etc. checks is that you're not counting on it being an identical ABI at each end. I'm saying the bit field packing is another way the ABIs at each end could differ, which is not currently accounted for. --=20 David Gibson (he or they) | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you, not the other way | around. http://www.ozlabs.org/~dgibson --X3tr89nPxP1841zT Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEO+dNsU4E3yXUXRK2zQJF27ox2GcFAmeay1UACgkQzQJF27ox 2Gc0TQ//fgojCh0mFBhpo+e6Ri7E8YRb++7mGPvYMhagwCt/5PVMZs2IqrpRJL0v t1wdfeIy+CEWIOsQfzwknIlB2HoG5WgG9IvaPXVCJXatfCnAwpyRg2yo3i4R8X8s 1yCxpZf7fVcs+C9JylbQTvKkbWYs//wzUdOOtNwPIJzeaPqrYD5LnjfG1SCmPLng NaFKsssCOrZlzn2iQT98Rwbj8mpH7ZMGJNn95fjr7svBrXNfJ8DoJN7cBJ4fgiSQ OR6jrbsi6zSR2NIcPfjsJ20Rwc8B8RQ3Zd2gp+r5v1DWgMVUi1rea652sDTqwbNY vGUvgiJ5gNEI/rHfrtP1weVZDNapPtAK/dWghHATgi8SjH7VCmGTJxKPY/4xyiaN nOOtiO029gtPJgyC8ienbwe/zZUoQShuvfpbkAa/NjU6xPJVspdjx5NMP3HUi6o/ Y+7eLUDIESk/UlvNcB/RaEfbso/ikl/+ujS8kTg72vx4hOetKwVg/YM6KG472dEq QOzl1WbvKW+ruHU8lKu8afsgcMab66ITHUAVcaS/dm4N9rolRo+IagI5CfKlsZHk Q4GuXnz9ojyGXE1jFbcCsJqQLdnrW4trmleiRIolxbsAJxdcmunmRG4GosNXlP2r T2BbI8XIUl9HvDkjI/qMUN8votnaPGxSwYXnxJ9qUx2i4WVWmwQ= =xxzs -----END PGP SIGNATURE----- --X3tr89nPxP1841zT--