Messages in this thread | | | Subject | Re: [PATCH] lro: IP fragment checking | From | Ben Hutchings <> | Date | Mon, 01 Dec 2008 22:09:39 +0000 |
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On Mon, 2008-12-01 at 16:53 -0500, Andrew Gallatin wrote: > David Miller wrote: > > From: Andrew Gallatin <gallatin@myri.com> > > Date: Mon, 01 Dec 2008 12:50:15 -0500 > > > >> As to whether or not to do it in the drivers/hardware or in the > >> LRO code, I favor doing it in the LRO code just so that it is not > >> missed in some driver. > > > > Then there is no point in the hardware doing the check, if > > we're going to check it anyways. > > > > That's part of my point about why this check doesn't belong > > here. > > What hardware does an explicit check for fragmentation?
Any that implements TCP/UDP checksumming properly.
> In most cases, aren't we just relying on the hardware checksum > to be wrong on fragmented packets? That works 99.999% of the time, > but the TCP checksum is pretty weak, and it is possible to > have a fragmented packet where the first fragment has the same > checksum as the entire packet. [...]
If your hardware/firmware wrongly claims to be able to verify the TCP/UDP checksum for an IP fragment, it seems to me you should deal with that in your driver or fix the firmware.
Ben.
-- Ben Hutchings, Senior Software Engineer, Solarflare Communications Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked.
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