From: Stephen Hemminger <stephen@networkplumber.org>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Peter Oskolkov <posk@google.com>,
David Miller <davem@davemloft.net>,
netdev@vger.kernel.org, Eric Dumazet <edumazet@google.com>,
Florian Westphal <fw@strlen.de>
Subject: Re: [PATCH net-next 1/3] ip: discard IPv4 datagrams with overlapping segments.
Date: Thu, 2 Aug 2018 16:56:55 -0700 [thread overview]
Message-ID: <20180802165655.11a0996e@xeon-e3> (raw)
In-Reply-To: <b8fcccc6-2946-b146-b136-3915c005fd26@gmail.com>
On Thu, 2 Aug 2018 16:33:55 -0700
Eric Dumazet <eric.dumazet@gmail.com> wrote:
> On 08/02/2018 03:54 PM, Stephen Hemminger wrote:
> > On Thu, 2 Aug 2018 22:45:58 +0000
> > Peter Oskolkov <posk@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 ;)
>
Agree with eric, go ahead and keep things local
next prev parent reply other threads:[~2018-08-03 1:50 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-02 22:45 [PATCH net-next 0/3] ip: Use rb trees for IP frag queue Peter Oskolkov
2018-08-02 22:45 ` [PATCH net-next 1/3] ip: discard IPv4 datagrams with overlapping segments Peter Oskolkov
2018-08-02 22:54 ` Stephen Hemminger
2018-08-02 23:33 ` Eric Dumazet
2018-08-02 23:56 ` Stephen Hemminger [this message]
2018-08-02 22:45 ` [PATCH net-next 2/3] net: modify skb_rbtree_purge to return the truesize of all purged skbs Peter Oskolkov
2018-08-02 22:46 ` [PATCH net-next 3/3] ip: use rb trees for IP frag queue Peter Oskolkov
2018-08-06 0:17 ` [PATCH net-next 0/3] ip: Use " David Miller
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