Re: git: 8c0d1eca7834 - main - sockbuf: retain backward compatibility with userland after d59bc188d652

On 5/31/22, Alexander V. Chernikov <melifaro@ipfw.ru> wrote:
>
>
>> 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).
>

it will prevent accidental changes

>> +#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>
>
>


-- 
Mateusz Guzik <mjguzik gmail.com>