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

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Date:   Sun, 26 Nov 2017 18:40:06 -0500 (EST)
From:   David Miller <davem@...emloft.net>
To:     zhanglkk1990@....com
Cc:     pshelar@...ira.com, netdev@...r.kernel.org, zhangliping02@...du.com
Subject: Re: [PATCH net] openvswitch: fix the incorrect flow action alloc
 size

From: zhangliping <zhanglkk1990@....com>
Date: Sat, 25 Nov 2017 22:02:12 +0800

> 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>

Applied, thanks.