netdev - Re: [net PATCH 3/5] bpf: remove mark access for SK

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Message-ID: <20171018173403.5m2d44vxuilciuqt@ast-mbp>
Date:   Wed, 18 Oct 2017 10:34:05 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     John Fastabend <john.r.fastabend@...il.com>
Cc:     davem@...emloft.net, netdev@...r.kernel.org, borkmann@...earbox.net
Subject: Re: [net PATCH 3/5] bpf: remove mark access for SK_SKB program types

On Wed, Oct 18, 2017 at 07:10:58AM -0700, John Fastabend wrote:
> From: John Fastabend <john.fastabend@...il.com>
> 
> The skb->mark field is a union with reserved_tailroom which is used
> in the TCP code paths from stream memory allocation. Allowing SK_SKB
> programs to set this field creates a conflict with future code
> optimizations, such as "gifting" the skb to the egress path instead
> of creating a new skb and doing a memcpy.
> 
> Because we do not have a released version of SK_SKB yet lets just
> remove it for now. A more appropriate scratch pad to use at the
> socket layer is dev_scratch, but lets add that in future kernels
> when needed.
> 
> Signed-off-by: John Fastabend <john.fastabend@...il.com>
> Acked-by: Daniel Borkmann <daniel@...earbox.net>

Acked-by: Alexei Starovoitov <ast@...nel.org>