netdev - Re: [PATCH iproute2-next 1/3] tc: p_ip6: Support pedit of IPv6 dsfield

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Date:   Thu, 02 Apr 2020 13:06:02 +0200
From:   Petr Machata <petrm@...lanox.com>
To:     David Ahern <dsahern@...il.com>
Cc:     Stephen Hemminger <stephen@...workplumber.org>,
        netdev@...r.kernel.org
Subject: Re: [PATCH iproute2-next 1/3] tc: p_ip6: Support pedit of IPv6 dsfield


David Ahern <dsahern@...il.com> writes:

> On 3/30/20 2:32 AM, Petr Machata wrote:
>> 
>> Stephen Hemminger <stephen@...workplumber.org> writes:
>> 
>>>> diff --git a/tc/p_ip6.c b/tc/p_ip6.c
>>>> index 7cc7997b..b6fe81f5 100644
>>>> --- a/tc/p_ip6.c
>>>> +++ b/tc/p_ip6.c
>>>> @@ -56,6 +56,22 @@ parse_ip6(int *argc_p, char ***argv_p,
>>>>  		res = parse_cmd(&argc, &argv, 4, TU32, 0x0007ffff, sel, tkey);
>>>>  		goto done;
>>>>  	}
>>>> +	if (strcmp(*argv, "traffic_class") == 0 ||
>>>> +	    strcmp(*argv, "tos") == 0 ||
>>>> +	    strcmp(*argv, "dsfield") == 0) {
>>>> +		NEXT_ARG();
>>>> +		tkey->off = 1;
>>>> +		res = parse_cmd(&argc, &argv, 1, TU32, RU8, sel, tkey);
>>>> +
>>>> +		/* Shift the field by 4 bits on success. */
>>>> +		if (!res) {
>>>> +			int nkeys = sel->sel.nkeys;
>>>> +			struct tc_pedit_key *key = &sel->sel.keys[nkeys - 1];
>>>> +			key->mask = htonl(ntohl(key->mask) << 4 | 0xf);
>>>> +			key->val = htonl(ntohl(key->val) << 4);
>>>> +		}
>>>> +		goto done;
>>>> +	}
>>> Why in the middle of the list?
>> 
>> Because that's the order IPv4 code does them.
>
> neither parse function uses matches() so the order should not matter.

It was purely a consistency thing. So you both seem to imply I should
move it to the end, so I'll do that in v2.

>> 
>>> Why three aliases for the same value?
>>> Since this is new code choose one and make it match what IPv6 standard
>>> calls that field.
>> 
>> TOS because flower also calls it TOS, even if it's the IPv6 field.
>> dsfield, because the IPv4 pedit also accepts this. I'm fine with just
>> accepting traffic_class though.
>> 
>
> that's probably the right thing to do since this is ipv6 related

All right, I'll send v2 with this fix.