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Re: Q: (ab)using zerocopy for drivers with alignment contraints

To: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Subject: Re: Q: (ab)using zerocopy for drivers with alignment contraints
From: "David S. Miller" <davem@xxxxxxxxxx>
Date: Mon, 11 Jun 2001 20:14:41 -0700 (PDT)
Cc: netdev@xxxxxxxxxxx
In-reply-to: <3B24F601.D732B35E@colorfullife.com>
References: <3B238B31.38F6D3ED@colorfullife.com> <15140.5474.324005.550559@pizda.ninka.net> <3B24F601.D732B35E@colorfullife.com>
Sender: owner-netdev@xxxxxxxxxxx
Manfred Spraul writes:
 > skb_copy_datagram & friends follow the fragment list. My function
 > doesn't/mustn't follow skb_shinfo(skb)->frag_list. Should I still call
 > it skb_copy_datagram{,_iovec}_kernel? I don't like functions with
 > similar names and subtile differences.

Why "mustn't it" follow the frag list?  I think it would be
"absolutely fantastic" if it did follow the frag list!  Then
we could optimize the forwarding of fragmented packets.

There is no subtle difference, make it do _exactly_ what
skb_copy_datagram{,_iovec}() does to userspace and name it
how I've asked you to name it.

What are you trying to avoid by not walking the frag_list?  A single
NULL pointer check?  Get real :-)

Later,
David S. Miller
davem@xxxxxxxxxx

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