From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stephen Hemminger <stephen@networkplumber.org>
Subject: Re: [Cake] [PATCH net-next v2] Add Common Applications Kept
 Enhanced (cake) qdisc
Date: Tue, 24 Apr 2018 08:11:26 -0700
Message-ID: <20180424081126.2e2f830a@xeon-e3>
References: <1512338775-3270-1-git-send-email-dave.taht@gmail.com>
        <20180424114407.5939-1-toke@toke.dk>
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To: Toke =?UTF-8?B?SMO4aWxhbmQtSsO4cmdlbnNlbg==?= <toke@toke.dk>
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On Tue, 24 Apr 2018 13:44:06 +0200
Toke H=C3=B8iland-J=C3=B8rgensen <toke@toke.dk> wrote:

> +struct tc_cake_xstats {
> +	__u16 version;
> +	__u16 tin_stats_size; /* =3D=3D sizeof(struct tc_cake_tin_stats) */
> +	__u32 capacity_estimate;
> +	__u32 memory_limit;
> +	__u32 memory_used;
> +	__u8  tin_cnt;
> +	__u8  avg_trnoff;
> +	__u16 max_netlen;
> +	__u16 max_adjlen;
> +	__u16 min_netlen;
> +	__u16 min_adjlen;
> +
> +	__u16 spare1;
> +	__u32 spare2;
> +
> +	struct tc_cake_tin_stats tin_stats[0]; /* keep last */
> +};

No versioning allowed in userspace API. You need to drop version and make
it permanent.