From: "David S. Miller" <davem@davemloft.net>
To: kaber@trash.net
Cc: herbert@gondor.apana.org.au, shemminger@osdl.org,
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 21:18:43 -0700 (PDT) [thread overview]
Message-ID: <20060515.211843.82450846.davem@davemloft.net> (raw)
In-Reply-To: <4469294D.6010509@trash.net>
From: Patrick McHardy <kaber@trash.net>
Date: Tue, 16 May 2006 03:22:21 +0200
> Patrick McHardy wrote:
> > 3) Clone the skb and have dev_queue_xmit_nit() consume it.
> >
> > That should actually be pretty easy.
>
> On second thought, thats not so great either. netdev_nit
> just globally signals that there are some taps, but we
> don't know if they're interested in a specific packet.
Yes, and all of these issues coming up are why we do the
dev_queue_xmit_nit() before not after we try to give it to the device.
Even the "NIT done" bit doesn't work, for cases like ICMP replies
which can reuse the SKB received, over loopback. Sure we can try to
forcefully clear the bit everywhere we reuse buffers for replies like
that, but I wish anyone trying to implement that the best of luck
finding all spots successfully.
To be honest, I don't think this bug is worth all the energy we are
trying to put into fixing it.
We get a double packet when the spinlock is hit, big deal.
prev parent reply other threads:[~2006-05-16 4:19 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-05-10 20:17 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
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 [this message]
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