Re: [libvirt] [libvirt PATCHv6 1/1] add DHCP snooping
David Stevens/Beaverton/IBM wrote on 03/22/2012 07:26:06 PM:
From: David Stevens/Beaverton/IBM
To: Eric Blake <eblake(a)redhat.com>
Cc: libvir-list(a)redhat.com, Stefan Berger/Watson/IBM@IBMUS
Date: 03/22/2012 07:26 PM
Subject: Re: [libvirt] [libvirt PATCHv6 1/1] add DHCP snooping
Eric Blake <eblake(a)redhat.com> wrote on 03/22/2012 03:54:31 PM:
>
> pthread_cancel() tends to imply that you are properly managing signal
> blocking across threads; we haven't used it anywhere else in libvirt,
> and I'm extremely wary of pulling it in now, as there's probably a lot
> of subtle bugs that it would expose. Are you sure you can't do this
in
> some other manner without dragging in pthread_cancel()?
Well, I was trying to avoid it in the earlier versions, but we ran
into races where a new snooper thread could start up on the same
interface
before the old one woke up and noticed it was supposed to die; the
old
thread would then interfere with the new thread in unpleasant ways.
Right. I had created several patches on top of your previous code. From
what I remember pretty much all scenarios were working: SIGHUP, multiple
IP addresses, suspend/resume... Some of the code that became necessary due
to the interaction of the threads really wasn't 'nice' (tricky)...
Stefan
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