From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gregory Haskins Subject: Re: [RFC PATCH] net: add dataref destructor to sk_buff Date: Fri, 13 Nov 2009 21:27:57 -0500 Message-ID: <4AFE15AD.6000208@gmail.com> References: <20091002141407.30224.54207.stgit@dev.haskins.net> <20091110115335.GC6989@redhat.com> <4AF919020200005A000586A9@sinclair.provo.novell.com> <20091110131722.GA19645@redhat.com> <4AF9747E.8020408@novell.com> <20091110143652.GB19645@redhat.com> <4AF98A8C.9040201@novell.com> <20091114011229.GA18580@gondor.apana.org.au> <4AFE08EF.2030308@gmail.com> <20091114022103.GA19020@gondor.apana.org.au> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig21C582F9350111BA33D27FDF" Cc: Gregory Haskins , "Michael S. Tsirkin" , alacrityvm-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, netdev@vger.kernel.org To: Herbert Xu Return-path: Received: from mail-yw0-f202.google.com ([209.85.211.202]:39752 "EHLO mail-yw0-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753359AbZKNC1z (ORCPT ); Fri, 13 Nov 2009 21:27:55 -0500 In-Reply-To: <20091114022103.GA19020@gondor.apana.org.au> Sender: netdev-owner@vger.kernel.org List-ID: This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig21C582F9350111BA33D27FDF Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Herbert Xu wrote: > On Fri, Nov 13, 2009 at 08:33:35PM -0500, Gregory Haskins wrote: >> Well, not with respect to the overall protocol, of course not. But wi= th >> respect to the buffer in question, it _has_ to be. Or am I missing >> something? >=20 > sendfile() has never guaranteed that the kernel is finished with > the underlying pages when it returns. >=20 > Cheers, Clearly there must be _some_ mechanism to synchronize (e.g. flush/barrier) though, right? Otherwise, that interface would seem to be quite prone to races and would likely be unusable. So what does said flush use to know when the buffer is free? -Greg --------------enig21C582F9350111BA33D27FDF Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG/MacGPG2 v2.0.11 (Darwin) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAkr+Fa0ACgkQP5K2CMvXmqHxCQCfeOSNrB4WUUHJlHAgXDuzEkVt q4oAn2Pc2/fD9iDBVXk6RcD6RRj+q28H =9nPK -----END PGP SIGNATURE----- --------------enig21C582F9350111BA33D27FDF--