netdev - Re: [PATCH net] openvswitch: fix the incorrect flow action alloc size

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Message-ID: <CAOrHB_AhxaxGuB+EiEpv7EreXsnMRJTDgTTyaFoBGoprPvkgEQ@mail.gmail.com>
Date:   Sun, 26 Nov 2017 23:53:31 +0530
From:   Pravin Shelar <pshelar@....org>
To:     zhangliping <zhanglkk1990@....com>
Cc:     Pravin Shelar <pshelar@...ira.com>,
        "David S. Miller" <davem@...emloft.net>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>,
        zhangliping <zhangliping02@...du.com>
Subject: Re: [PATCH net] openvswitch: fix the incorrect flow action alloc size

On Sat, Nov 25, 2017 at 7:32 PM, zhangliping <zhanglkk1990@....com> wrote:
> From: zhangliping <zhangliping02@...du.com>
>
> If we want to add a datapath flow, which has more than 500 vxlan outputs'
> action, we will get the following error reports:
>   openvswitch: netlink: Flow action size 32832 bytes exceeds max
>   openvswitch: netlink: Flow action size 32832 bytes exceeds max
>   openvswitch: netlink: Actions may not be safe on all matching packets
>   ... ...
>
> It seems that we can simply enlarge the MAX_ACTIONS_BUFSIZE to fix it, but
> this is not the root cause. For example, for a vxlan output action, we need
> about 60 bytes for the nlattr, but after it is converted to the flow
> action, it only occupies 24 bytes. This means that we can still support
> more than 1000 vxlan output actions for a single datapath flow under the
> the current 32k max limitation.
>
> So even if the nla_len(attr) is larger than MAX_ACTIONS_BUFSIZE, we
> shouldn't report EINVAL and keep it move on, as the judgement can be
> done by the reserve_sfa_size.
>
> Signed-off-by: zhangliping <zhangliping02@...du.com>

Thanks for the patch.

Acked-by: Pravin B Shelar <pshelar@....org>