From: Patrick McHardy <kaber@trash.net>
To: "David S. Miller" <davem@davemloft.net>
Cc: ranjitm@google.com, akpm@osdl.org, linux-kernel@vger.kernel.org,
netdev@vger.kernel.org
Subject: Re: [PATCH] tcpdump may trace some outbound packets twice.
Date: Mon, 15 May 2006 23:41:52 +0200 [thread overview]
Message-ID: <4468F5A0.3040404@trash.net> (raw)
In-Reply-To: <20060515.142645.94689626.davem@davemloft.net>
David S. Miller wrote:
> From: Ranjit Manomohan <ranjitm@google.com>
> Date: Mon, 15 May 2006 14:19:06 -0700 (PDT)
>
>
>>Heres a new version which does a copy instead of the clone to avoid
>>the double cloning issue.
>
>
> I still very much dislike this patch because it is creating
> 1 more clone per packet than is actually necessary and that
> is very expensive.
>
> dev_queue_xmit_nit() is going to clone whatever SKB you send into
> there, so better to just bump the reference count (with skb_get())
> instead of cloning or copying.
I think this would break the tc actions. Some actions call
pskb_expand_head() on input, which BUGs on skb_shared(skb).
They can't clone the skb instead because the functions
doing that don't own it, the caller would continue with the
old skb.
next prev parent reply other threads:[~2006-05-15 21:41 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-05-10 20:17 [PATCH] tcpdump may trace some outbound packets twice Ranjit Manomohan
2006-05-14 10:10 ` Andrew Morton
2006-05-14 15:58 ` Ranjit Manomohan
2006-05-14 20:42 ` David S. Miller
2006-05-15 21:19 ` Ranjit Manomohan
2006-05-15 21:26 ` David S. Miller
2006-05-15 21:41 ` Patrick McHardy [this message]
2006-05-15 23:11 ` Ranjit Manomohan
2006-05-15 23:41 ` Stephen Hemminger
2006-05-16 0:08 ` David S. Miller
2006-05-16 0:21 ` Patrick McHardy
2006-05-16 0:48 ` Tom Young
2006-05-16 0:37 ` Herbert Xu
2006-05-16 1:17 ` Patrick McHardy
2006-05-16 1:20 ` Herbert Xu
2006-05-16 1:22 ` Patrick McHardy
2006-05-16 4:18 ` David S. Miller
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