linux-kernel - Re: [PATCH net 1/3] net: fec: dynamically set the NETDEV_XDP_ACT_NDO

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <87mt0bb5cm.fsf@toke.dk>
Date:   Wed, 05 Jul 2023 01:54:17 +0200
From:   Toke Høiland-Jørgensen <toke@...hat.com>
To:     Andrew Lunn <andrew@...n.ch>, wei.fang@....com
Cc:     davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com, ast@...nel.org, daniel@...earbox.net,
        hawk@...nel.org, john.fastabend@...il.com, shenwei.wang@....com,
        xiaoning.wang@....com, netdev@...r.kernel.org, linux-imx@....com,
        linux-kernel@...r.kernel.org, bpf@...r.kernel.org
Subject: Re: [PATCH net 1/3] net: fec: dynamically set the
 NETDEV_XDP_ACT_NDO_XMIT feature of XDP

Andrew Lunn <andrew@...n.ch> writes:

> On Tue, Jul 04, 2023 at 04:29:14PM +0800, wei.fang@....com wrote:
>> From: Wei Fang <wei.fang@....com>
>> 
>> When a XDP program is installed or uninstalled, fec_restart() will
>> be invoked to reset MAC and buffer descriptor rings. It's reasonable
>> not to transmit any packet during the process of reset. However, the
>> NETDEV_XDP_ACT_NDO_XMIT bit of xdp_features is enabled by default,
>> that is to say, it's possible that the fec_enet_xdp_xmit() will be
>> invoked even if the process of reset is not finished. In this case,
>> the redirected XDP frames might be dropped and available transmit BDs
>> may be incorrectly deemed insufficient. So this patch disable the
>> NETDEV_XDP_ACT_NDO_XMIT feature by default and dynamically configure
>> this feature when the bpf program is installed or uninstalled.
>
> I don't know much about XDP, so please excuse what might be a stupid
> question.
>
> Is this a generic issue? Should this
> xdp_features_clear_redirect_target(dev) /
> xdp_features_set_redirect_target(dev, false) be done in the core?

No, because not all drivers require an XDP program to be attached to
support being a redirect target (which is one of the reasons we
introduced these feature bits in the first place :)).

-Toke