netdev - Re: [PATCH] tcp: splice as many packets as possible at once

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Message-ID: <20090114112808.GA18662@gondor.apana.org.au>
Date:	Wed, 14 Jan 2009 22:28:08 +1100
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	David Miller <davem@...emloft.net>
Cc:	jarkao2@...il.com, zbr@...emap.net, dada1@...mosbay.com, w@....eu,
	ben@...s.com, mingo@...e.hu, linux-kernel@...r.kernel.org,
	netdev@...r.kernel.org, jens.axboe@...cle.com
Subject: Re: [PATCH] tcp: splice as many packets as possible at once

On Wed, Jan 14, 2009 at 01:29:19AM -0800, David Miller wrote:
> 
> It's a simple fix, but as Herbert stated it leaves other ->sendpage()
> implementations exposed to data corruption when the from side of the
> pipe buffer is a socket.
> 
> That, to me, is almost worse than a bad fix.

Yep, so far nobody has verified the disk path at all.  So for all
we know, if there is a delay on the way to disk, the exact same
thing can occur.

Besides, the PageSlab thing is going to copy for network to network
anyway.

> So, I've put together a full commit message and Jarek's patch
> below.  One thing I notice is that the silly skb_clone() done
> by SKB splicing is no longer necessary.
> 
> We could get rid of that to offset (some) of the cost we are
> adding with this bug fix.
> 
> Comments?

Yes that's probably a good idea.

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@...dor.apana.org.au>
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