On 08/02/2018 03:54 PM, Stephen Hemminger wrote:
> On Thu, 2 Aug 2018 22:45:58 +0000
> Peter Oskolkov <p...@google.com> wrote:
>
>> diff --git a/include/uapi/linux/snmp.h b/include/uapi/linux/snmp.h
>> index e5ebc83827ab..da1a144f1a51 100644
>> --- a/include/uapi/linux/snmp.h
>> +++ b/include/uapi/linux/snmp.h
>> @@ -40,6 +40,7 @@ enum
>> IPSTATS_MIB_REASMREQDS, /* ReasmReqds */
>> IPSTATS_MIB_REASMOKS, /* ReasmOKs */
>> IPSTATS_MIB_REASMFAILS, /* ReasmFails */
>> + IPSTATS_MIB_REASM_OVERLAPS, /* ReasmOverlaps */
>> IPSTATS_MIB_FRAGOKS, /* FragOKs */
>> IPSTATS_MIB_FRAGFAILS, /* FragFails */
>> IPSTATS_MIB_FRAGCREATES, /* FragCreates */
>
> Inserting new entries in the middle of an enum means the numeric
> values will change. Isn't this going to break userspace ABI?
>
I would argue the only exported thing from the kernel are the Key:Val in the
/proc files.
Not sure why these enum are uapi.
Commit 46c2fa39877ed70415ee2b1acfb9129e956f6de4 added
LINUX_MIB_TCPFASTOPENBLACKHOLE in the middle,
and really nobody complained.
Commit 0604475119de5f80dc051a5db055c6a2a75bd542 added
LINUX_MIBSTCPMEMORYPRESSURESCHRONO
in the middle as well.
I am pretty sure we should maintain locality of these counters to lower number
of dirtied cache lines, say under IP frag DDOS ;)
