netdev - Re: [PATCH v4 net-next] net:sched: add action inheritdsfield to skbedit

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Message-ID: <785f294c-080a-bfb4-5c7f-3ab48056649f@digirati.com.br>
Date:   Tue, 19 Jun 2018 08:39:41 -0400
From:   Michel Machado <michel@...irati.com.br>
To:     Jamal Hadi Salim <jhs@...atatu.com>,
        "Fu, Qiaobin" <qiaobinf@...edu>,
        "davem@...emloft.net" <davem@...emloft.net>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
        "xiyou.wangcong@...il.com" <xiyou.wangcong@...il.com>
Subject: Re: [PATCH v4 net-next] net:sched: add action inheritdsfield to
 skbedit

On 06/19/2018 08:01 AM, Jamal Hadi Salim wrote:
> Per my previous comments, why do we need the
> TCA_SKBEDIT_FLAGS TLV? Isnt SKBEDIT_F_INHERITDSFIELD
> sufficient? i.e in tcf_skbedit_init() check for
> d->flags&SKBEDIT_F_INHERITDSFIELD then set skb->priority
> and flags|=SKBEDIT_F_INHERITDSFIELD

    Notice that, different from skbmod, there's no field parm->flags in 
skbedit. Skbedit infers the flags in d->flags from the presence of the 
parameters of each of its actions. But SKBEDIT_F_INHERITDSFIELD has no 
parameter and adding field parm->flags breaks backward compatibility 
with user space as pointed out by Marcelo Ricardo Leitner. Our solution 
was to add TCA_SKBEDIT_FLAGS, so SKBEDIT_F_INHERITDSFIELD and future 
flag-only actions can be added.

[ ]'s
Michel Machado