Am 25.05.2015 um 15:09 schrieb Nicolas Dichtel:

Le 25/05/2015 12:55, Alexander Holler a écrit :

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Am 25.05.2015 um 09:45 schrieb Nicolas Dichtel:

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Le 22/05/2015 22:50, Alexander Holler a écrit :

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First I think if NETLINK_LISTEN_ALL_NSID is enabled, a dump
of the interfaces through RTM_GETLINK together with NLM_F_DUMP and
NLM_F_REQUEST should return all interfaces of all reachable namespaces.

This option is only for 'listening', ie spontaneous notifications
from the
kernel. It does nothing for request.

The problem is that you need informations about the affected
interfaces. E.g. if
you receive an NEWADDR or NEWROUTE for some interface (indicated by
the index of
the interface) in a(nother) namespace, how do you get informations
about that
interface, if not by a dump which includes the interfaces of these
namespaces
too? Without knowledge about the interface, these messages are not
very usable. ;)

Yes, this is the right things.

Usually, a daemon opens a socket to listen netlink event. Then, it opens
another netlink socket to dump the configuration (interfaces, addresses,
routes, etc.) and fill its internal structures. Starting from that
point, for
most of configuration parameters, it doesn't need anymore to do dumps
and thus
it can close the second socket. This allows your daemon to have only one
socket
to monitor a set a netns.
Look at iproute for example, it starts by dumping all interfaces before
executing the specified command.

Hmm, sounds like we're talking in different rooms about the same thing 
in regard to the dump. ;)

I just wanted to explain why I think this series misses the (extended) 
dump which includes all interfaces (those of other namespaces too).

How does one use NETLINK_LISTEN_ALL_NSID without beeing able to dump all 
the interfaces of namespaces your patch series might send messages for?

The only way I currently see, is to start the listening part before any 
namespace is created. Doing so, it can fill it's internal structures 
with the RTM_NEWLINK messages (besides that missing one for lo). But how 
do you get these RTM_NEWLINK messages for already created namespaces and 
their interfaces, if not by a dump?

Regards,

Alexander Holler