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Message-ID: <20101009103136.341104c5@nehalam>
Date: Sat, 9 Oct 2010 10:31:36 -0700
From: Stephen Hemminger <shemminger@...tta.com>
To: David Miller <davem@...emloft.net>
Cc: eric.dumazet@...il.com, leitao@...ux.vnet.ibm.com,
netdev@...r.kernel.org, fubar@...ibm.com
Subject: Re: [PATCH] ehea: Fix a checksum issue on the receive path
On Sat, 09 Oct 2010 09:20:43 -0700 (PDT)
David Miller <davem@...emloft.net> wrote:
> From: Eric Dumazet <eric.dumazet@...il.com>
> Date: Fri, 08 Oct 2010 16:36:17 +0200
>
> > I am pretty sure most (if not all) netdev drivers pass the packet with
> > invalid checksum to upper stack, so that we can increment appropriate
> > SNMP counters, in IP stack or UDP/TCP/whatever stack.
> >
> > tg3, bnx2, e1000, skge, sky2, bnx2x, niu, r8169, igb, ... seems to do
> > that.
>
> Drivers _must_ send up all packets, even those with bad checksums,
> without exception.
>
> Otherwise protocol statistics get lost, netfilter log entries go
> missing, etc.
Also hardware checksum can be wrong/broken. By passing up a packet
which the driver thinks is bad, the software can still work.
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