netdev - Re: [PATCHv2 iproute2 net-next] tc: m_mirred: Fix parsing of 'index' optional argument

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Message-ID: <20161129123405.4008d526@samsung9>
Date:   Tue, 29 Nov 2016 12:34:05 -0800
From:   Stephen Hemminger <stephen@...workplumber.org>
To:     Shmulik Ladkani <shmulik.ladkani@...il.com>
Cc:     Phil Sutter <phil@....cc>, Jamal Hadi Salim <jhs@...atatu.com>,
        netdev@...r.kernel.org
Subject: Re: [PATCHv2 iproute2 net-next] tc: m_mirred: Fix parsing of
 'index' optional argument

On Thu, 27 Oct 2016 22:00:40 +0300
Shmulik Ladkani <shmulik.ladkani@...il.com> wrote:

> Hi,
> 
> On Thu, 27 Oct 2016 16:56:43 +0200 Phil Sutter <phil@....cc> wrote:
> > > Actual code, since first committed, attempts to parse "index" as 1st
> > > argument (without success), see parse_mirred():
> > > 
> > > 	if (matches(*argv, "egress") == 0 || matches(*argv, "index") == 0) {
> > > 		int ret = parse_egress(a, &argc, &argv, tca_id, n);    
> > 
> > Oh, I missed that! But to me this looks like the author wanted to avoid
> > erroring out with "mirred option not supported index" in case of missing
> > 'egress' keyword.  
> 
> Could be; Not that it matters much, but evidence in parse_egress() shows
> that it DOES try to parse and store "index" EVEN if no "egress" seen YET.
> 
> > Yeah, I'd go with least effort approach, i.e. not adding any additional
> > flexibility in arg parsing. Since the docs never stated otherwise, I
> > don't think it was a real issue for users.  
> 
> Sure. It never really worked ;)
> 
> If we go that way, then some code in parse_direction needs to be
> eliminated/restructured; So we'll end up with:
>  - less code in parse_direction
>  - not adding any additional flexibility in arg parsing
>  - bigger diff than suggested
> 
> Stephen, Jamal, do you have any preference here?

My only demand is not to break existing users.
Jamal is the original developer of mirred so I would like his feedback.