netdev - Re: [PATCH iproute2] iplink: work around rtattr length limits for IFLA_VFINFO

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Message-ID: <20210115155325.7811b052@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Fri, 15 Jan 2021 15:53:25 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     Edwin Peer <edwin.peer@...adcom.com>
Cc:     netdev@...r.kernel.org,
        Stephen Hemminger <stephen@...workplumber.org>,
        Andrew Gospodarek <andrew.gospodarek@...adcom.com>,
        Michael Chan <michael.chan@...adcom.com>,
        Michal Kubecek <mkubecek@...e.cz>
Subject: Re: [PATCH iproute2] iplink: work around rtattr length limits for
 IFLA_VFINFO_LIST

On Fri, 15 Jan 2021 14:59:50 -0800 Edwin Peer wrote:
> The maximum possible length of an RTNL attribute is 64KB, but the
> nested VFINFO list exceeds this for more than about 220 VFs (each VF
> consumes approximately 300 bytes, depending on alignment and optional
> fields). Exceeding the limit causes IFLA_VFINFO_LIST's length to wrap
> modulo 16 bits in the kernel's nla_nest_end().

Let's add Michal to CC, my faulty memory tells me he was fighting with
this in the past.