netdev - Re: [PATCH net] net: openvswitch: fix TTL decrement action netlink message format

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Date:   Mon, 23 Nov 2020 20:36:39 +0100
From:   Matteo Croce <mcroce@...ux.microsoft.com>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     Eelco Chaudron <echaudro@...hat.com>, netdev@...r.kernel.org,
        David Miller <davem@...emloft.net>, dev@...nvswitch.org,
        Pravin B Shelar <pshelar@....org>, bindiyakurle@...il.com,
        Ilya Maximets <i.maximets@....org>
Subject: Re: [PATCH net] net: openvswitch: fix TTL decrement action netlink
 message format

On Fri, Nov 20, 2020 at 10:12 PM Jakub Kicinski <kuba@...nel.org> wrote:
>
> On Thu, 19 Nov 2020 04:04:04 -0500 Eelco Chaudron wrote:
> > Currently, the openvswitch module is not accepting the correctly formated
> > netlink message for the TTL decrement action. For both setting and getting
> > the dec_ttl action, the actions should be nested in the
> > OVS_DEC_TTL_ATTR_ACTION attribute as mentioned in the openvswitch.h uapi.
>
> IOW this change will not break any known user space, correct?
>
> But existing OvS user space already expects it to work like you
> make it work now?
>
> What's the harm in leaving it as is?
>
> > Fixes: 744676e77720 ("openvswitch: add TTL decrement action")
> > Signed-off-by: Eelco Chaudron <echaudro@...hat.com>
>
> Can we get a review from OvS folks? Matteo looks good to you (as the
> original author)?
>

Hi,

I think that the userspace still has to implement the dec_ttl action;
by now dec_ttl is implemented with set_ttl().
So there is no breakage yet.

Eelco, with this fix we will encode the netlink attribute in the same
way for the kernel and netdev datapath?

If so, go for it.


> > -     err = __ovs_nla_copy_actions(net, attr, key, sfa, eth_type,
> > +     err = __ovs_nla_copy_actions(net, actions, key, sfa, eth_type,
> >                                    vlan_tci, mpls_label_count, log);
> >       if (err)
> >               return err;
>
> You're not canceling any nests on error, I assume this is normal.
>
> > +     add_nested_action_end(*sfa, action_start);
> >       add_nested_action_end(*sfa, start);
> >       return 0;
> >  }
>


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