netdev - RE: [PATCH net-next 2/2] net: optimize skb_postpull

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Date:   Fri, 3 Dec 2021 17:41:36 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Eric Dumazet' <edumazet@...gle.com>,
        David Lebrun <dlebrun@...gle.com>
CC:     Vladimir Oltean <olteanv@...il.com>,
        Eric Dumazet <eric.dumazet@...il.com>,
        "David S . Miller" <davem@...emloft.net>,
        "Jakub Kicinski" <kuba@...nel.org>, netdev <netdev@...r.kernel.org>
Subject: RE: [PATCH net-next 2/2] net: optimize skb_postpull_rcsum()

...
> > There are also 40 csum_partial(buf, len, 0).
> > If all the buffer is zero they'll return zero - invalid.
> > They ought to be changed to csum_partial(buf, len, 0xffff).
> >
> 
> Please point where all zero buffers can be valid in the first place.

They probably can't be.
But I bet a lot of the code was written without realising it mattered.

A quick scan does imply that they are all probably ok.

But I have spotted 18 ~csum_fold() - they may be dubious.

	David

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