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Date:   Wed, 8 Sep 2021 08:52:49 +0200 (CEST)
From:   Jan Engelhardt <jengelh@inai.de>
To:     Duncan Roe <duncan_roe@optusnet.com.au>
cc:     Florian Westphal <fw@strlen.de>,
        Cole Dishington <Cole.Dishington@alliedtelesis.co.nz>,
        pablo@netfilter.org, kadlec@netfilter.org, davem@davemloft.net,
        kuba@kernel.org, shuah@kernel.org, linux-kernel@vger.kernel.org,
        netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
        netdev@vger.kernel.org,
        Anthony Lineham <anthony.lineham@alliedtelesis.co.nz>,
        Scott Parlane <scott.parlane@alliedtelesis.co.nz>,
        Blair Steven <blair.steven@alliedtelesis.co.nz>
Subject: Re: [PATCH net v2] net: netfilter: Fix port selection of FTP for
 NF_NAT_RANGE_PROTO_SPECIFIED
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On Wednesday 2021-09-08 04:22, Duncan Roe wrote:
>> >Either use if (nat->range_info.min_proto.all || ...
>> >
>> >or use ntohs().  I will leave it up to you if you prefer
>> >ntohs(nat->range_info.min_proto.all) == 0 or
>> >nat->range_info.min_proto.all == ntohs(0).
>>
>> If one has the option, one should always prefer to put htons/htonl on
>> the side with the constant literal;
>> Propagation of constants and compile-time evaluation is the target.
>>
>> That works for some other functions as well (e.g.
>> strlen("fixedstring")).
>
>When comparing against constant zero, why use htons/htonl at all?

Logical correctness.
Remember, it was the sparse tool that complained in the first place.