netdev - Re: [PATCH net-next] tcp: allow zerocopy with fastopen

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Date:   Fri, 25 Jan 2019 09:06:25 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Willem de Bruijn <willemdebruijn.kernel@...il.com>,
        netdev@...r.kernel.org
Cc:     davem@...emloft.net, ycheng@...gle.com, edumazet@...gle.com,
        alexey.kodanev@...cle.com, Willem de Bruijn <willemb@...gle.com>
Subject: Re: [PATCH net-next] tcp: allow zerocopy with fastopen



On 01/25/2019 08:17 AM, Willem de Bruijn wrote:
> From: Willem de Bruijn <willemb@...gle.com>
> 
> Accept MSG_ZEROCOPY in all the TCP states that allow sendmsg. Remove
> the explicit check for ESTABLISHED and CLOSE_WAIT states.
> 
> This requires correctly handling zerocopy state (uarg, sk_zckey) in
> all paths reachable from other TCP states. Such as the EPIPE case
> in sk_stream_wait_connect, which a sendmsg() in incorrect state will
> now hit. Most paths are already safe.
> 
> Only extension needed is for TCP Fastopen active open. This can build
> an skb with data in tcp_send_syn_data. Pass the uarg along with other
> fastopen state, so that this skb also generates a zerocopy
> notification on release.
> 
> Tested with active and passive tcp fastopen packetdrill scripts at
> https://github.com/wdebruij/packetdrill/commit/1747eef03d25a2404e8132817d0f1244fd6f129d
> 
> Signed-off-by: Willem de Bruijn <willemb@...gle.com>
> ---

Let see if syzkaller finds issues with this :)

Signed-off-by: Eric Dumazet <edumazet@...gle.com>