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Message-ID: <4AFE15AD.6000208@gmail.com>
Date: Fri, 13 Nov 2009 21:27:57 -0500
From: Gregory Haskins <gregory.haskins@gmail.com>
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To: Herbert Xu <herbert@gondor.apana.org.au>
CC: Gregory Haskins <ghaskins@novell.com>,
       "Michael S. Tsirkin" <mst@redhat.com>,
       alacrityvm-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org,
       netdev@vger.kernel.org
Subject: Re: [RFC PATCH] net: add dataref destructor to sk_buff
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>
In-Reply-To: <20091114022103.GA19020@gondor.apana.org.au>
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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


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