Re: [PATCH] veth: replace iflink by a dedicated symlink in sysfs

 ❦ 19 août 2015 13:00 +0200, Jiri Benc [off-list ref] :

quoted

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.
-- 
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