Re: [PATCH] lro: IP fragment checking

From: Andrew Gallatin
Date: Mon Dec 01 2008 - 16:53:47 EST

David Miller wrote:
From: Andrew Gallatin <gallatin@xxxxxxxx>
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

What hardware does an explicit check for fragmentation?
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.

I'd rather have a fragmentation check at the LRO layer to remove
any ambiguity. But if you still object, I'll at least have to
submit a patch which adds an explicit check in myri10ge.

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