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Subject: Re: [PATCH 1/2] Revert "xfrm: interface with if_id 0 should return
 error"
To:     Paul Chaignon <paul@cilium.io>, Eyal Birger <eyal.birger@gmail.com>
Cc:     netdev@vger.kernel.org,
        Steffen Klassert <steffen.klassert@secunet.com>
References: <20220301131512.1303-1-kailueke@linux.microsoft.com>
 <CAHsH6Gtzaf2vhSv5sPpBBhBww9dy8_E7c0utoqMBORas2R+_zg@mail.gmail.com>
 <d5e58052-86df-7ffa-02a0-fc4db5a7bbdf@linux.microsoft.com>
 <CAHsH6GsxaSgGkF9gkBKCcO9feSrsXsuNBdKRM_R8=Suih9oxSw@mail.gmail.com>
 <20220301150930.GA56710@Mem>
From:   =?UTF-8?B?S2FpIEzDvGtl?= <kailueke@linux.microsoft.com>
Message-ID: <dcc83e93-4a28-896c-b3d3-8d675bb705eb@linux.microsoft.com>
Date:   Tue, 1 Mar 2022 16:48:38 +0100
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> I agree with Eyal here.  As far as Cilium is concerned, this is not
> causing any regression.  Only the second commit, 68ac0f3810e7 ("xfrm:
> state and policy should fail if XFRMA_IF_ID 0") causes issues in a
> previously-working setup in Cilium.  We don't use xfrm interfaces.
>
I see this as a very generic question of changing userspace behavior or
not, regardless if we know how many users are affected, and from what I
know there are similar cases in the kernel where the response was that
breaking userspace is a no go - even if the intention was to be helpful
by having early errors.

Greets,
Kai