Date: Tue, 31 May 2022 21:19:42 +0100 From: "Alexander V. Chernikov" <melifaro@ipfw.ru> To: Mateusz Guzik <mjguzik@gmail.com> Cc: "Alexander V. Chernikov" <melifaro@freebsd.org>, "src-committers@freebsd.org" <src-committers@freebsd.org>, "dev-commits-src-all@freebsd.org" <dev-commits-src-all@freebsd.org>, "dev-commits-src-main@freebsd.org" <dev-commits-src-main@freebsd.org> Subject: Re: git: 8c0d1eca7834 - main - sockbuf: retain backward compatibility with userland after d59bc188d652 Message-ID: <5A6DF60F-9584-43D4-BBF8-18634742A7C3@ipfw.ru> In-Reply-To: <CAGudoHG1v1f86v8mGjs7W5hq1ibrjKaJ4fZTyxAfAufuYD6A0A@mail.gmail.com> References: <202205301510.24UFAxvj014259@gitrepo.freebsd.org> <CAGudoHGptA4h2Nvb06WCTP7iXbWMNGgcUgiCeaFL0cXz=7TGnw@mail.gmail.com> <8909171653936542@iva6-17bf07036239.qloud-c.yandex.net> <CAGudoHG1v1f86v8mGjs7W5hq1ibrjKaJ4fZTyxAfAufuYD6A0A@mail.gmail.com>
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> On 31 May 2022, at 15:33, Mateusz Guzik <mjguzik@gmail.com> wrote:
>
> On 5/30/22, Alexander V. Chernikov <melifaro@ipfw.ru> wrote:
>>
>>
>> 30.05.2022, 16:18, "Mateusz Guzik" <mjguzik@gmail.com>:
>>>
>>> should probably CTASSERT on size then
>>
>> Sorry, I’m afraid I don’t get it. Could you please clarify?
>>>
>
> diff --git a/sys/sys/socketvar.h b/sys/sys/socketvar.h
> index 249e0800f915..5fc21206b1bf 100644
> --- a/sys/sys/socketvar.h
> +++ b/sys/sys/socketvar.h
> @@ -586,6 +586,14 @@ struct xsocket {
> } so_rcv, so_snd;
> };
>
> +#if _LP64
> +_Static_assert(sizeof(struct xsocket) == 240, "bad”)
Ah, got it!
Well, the rationale for the commit was not to absolutely prevent structure size changes - there may be many perfectly valid reasons to do so.
IIRC policy suggests it acceptable between the major revisions.
In the case of original change - removal of mbuf counters - backward compatibility (e.g. keeping structure size the same) does not cost us anything.
sockstat(1) from 13 will work on 14 (at least for now).
> +#elsif _LP32
> +....
> +#else
> +#error "port me"
> +#endif
> +
> #ifdef _KERNEL
> void sotoxsocket(struct socket *so, struct xsocket *xso);
> void sbtoxsockbuf(struct sockbuf *sb, struct xsockbuf *xsb);
>
>>> On 5/30/22, Alexander V. Chernikov <melifaro@freebsd.org> wrote:
>>>>
>>>> The branch main has been updated by melifaro:
>>>>
>>>> URL:
>>>> https://cgit.FreeBSD.org/src/commit/?id=8c0d1eca7834bfd5a05c86bf20a7600917057492
>>>>
>>>> commit 8c0d1eca7834bfd5a05c86bf20a7600917057492
>>>> Author: Alexander V. Chernikov <melifaro@FreeBSD.org>
>>>> AuthorDate: 2022-05-30 14:56:25 +0000
>>>> Commit: Alexander V. Chernikov <melifaro@FreeBSD.org>
>>>> CommitDate: 2022-05-30 15:10:53 +0000
>>>>
>>>> sockbuf: retain backward compatibility with userland after
>>>> d59bc188d652
>>>>
>>>> Add spare fields to xsockbuf in place of sb_mcnt / sb_ccnt to avoid
>>>> rebuilding userland binaries like sockstat(1).
>>>>
>>>> Reviewed by: glebius
>>>> ---
>>>> sys/sys/socketvar.h | 2 ++
>>>> 1 file changed, 2 insertions(+)
>>>>
>>>> diff --git a/sys/sys/socketvar.h b/sys/sys/socketvar.h
>>>> index 52b9376f0559..249e0800f915 100644
>>>> --- a/sys/sys/socketvar.h
>>>> +++ b/sys/sys/socketvar.h
>>>> @@ -577,6 +577,8 @@ struct xsocket {
>>>> uint32_t sb_cc;
>>>> uint32_t sb_hiwat;
>>>> uint32_t sb_mbcnt;
>>>> + uint32_t sb_spare0; /* was sb_mcnt */
>>>> + uint32_t sb_spare1; /* was sb_ccnt */
>>>> uint32_t sb_mbmax;
>>>> int32_t sb_lowat;
>>>> int32_t sb_timeo;
>>>>
>>>
>>>
>>> --
>>> Mateusz Guzik <mjguzik gmail.com>
>>
>
>
> --
> Mateusz Guzik <mjguzik gmail.com>
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