[Bug 959037] Re: NM-controlled dnsmasq prevents other DNS servers from starting

[Simon Kelley]

On 20/06/12 10:56, Thomas Hood wrote:
> I can imagine that it will take a lot of care to avoid introducing races
> inside dnsmasq. 

It's OK: notification of new interfaces comes via netlink, so it gets
synchronised via the select() call just like everything else.

Have I mentioned yet that Simon is a hero?

:-)

New code is in git (and I released 2.63test1) change --bind-interfaces
to --bind-dynamic as see how it goes.

> 
> Do we have to worry about races outside of dnsmasq?  Suppose someone was
> running dnsmasq in unbound mode and has now switched to the new improved
> dnsmasq in bind-interfaces-dynamically mode. Now an interface comes up
> but there is a delay before dnsmasq notices this and starts listening on
> it. Problem?

Because it's using netlink rather than polling, the delay is pretty
short (I know that's not a solution to races, but it does help.)

Simon.

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Title:
  NM-controlled dnsmasq prevents other DNS servers from starting

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