From: Vincent Bernat <vincent@bernat•im>
To: Jiri Benc <jbenc@redhat•com>
Cc: "David S. Miller" <davem@davemloft•net>,
netdev@vger•kernel.org,
Nicolas Dichtel <nicolas.dichtel@6wind•com>
Subject: Re: [PATCH] veth: replace iflink by a dedicated symlink in sysfs
Date: Wed, 19 Aug 2015 14:13:00 +0200 [thread overview]
Message-ID: <87bne38oj7.fsf@zoro.exoscale.ch> (raw)
In-Reply-To: <20150819130013.1a847627@griffin> (Jiri Benc's message of "Wed, 19 Aug 2015 13:00:13 +0200")
❦ 19 août 2015 13:00 +0200, Jiri Benc <jbenc@redhat•com> :
>> While the documentation doesn't say exactly what kind of relationship
>> iflink should represent, until a45253, only lower devices were
>> advertised this way. While veth cannot have a lower device, using iflink
>> to advertise the peer may create infinite loops in programs using iflink
>> to discover device topology.
>>
>> Instead of advertising the peer link with iflink, a symbolic link "peer"
>> is added to each peer.
>
> By removing veth_get_iflink, you're also stopping IFLA_LINK being
> advertised in netlink messages, which consequently makes impossible to
> reliably match veth peers across name spaces again. This would be a
> huge step backwards.
That's the main goal of this patch: advertising the peer link as
IFLA_LINK attribute triggers an infinite loop in userland software when
they follow iflink to discover network devices topology. iflink has
always been the index of a lower device. If a sysfs symbolic link is not
good enough, I can propose a new IFLA_PEER attribute instead.
--
How apt the poor are to be proud.
-- William Shakespeare, "Twelfth-Night"
next prev parent reply other threads:[~2015-08-19 12:23 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <87fv3ier4s.fsf@zoro.exoscale.ch>
2015-08-19 6:44 ` Regression in 4.1 with veth and IFLA_LINK Vincent Bernat
2015-08-19 6:44 ` [PATCH] veth: replace iflink by a dedicated symlink in sysfs Vincent Bernat
2015-08-19 11:00 ` Jiri Benc
2015-08-19 12:13 ` Vincent Bernat [this message]
2015-08-19 12:38 ` Jiri Benc
2015-08-19 12:48 ` Vincent Bernat
2015-08-19 16:33 ` Nicolas Dichtel
2015-08-20 11:53 ` Jiri Benc
2015-08-20 14:31 ` Nicolas Dichtel
2015-08-20 21:07 ` David Miller
2015-08-22 20:51 ` Vincent Bernat
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