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Re: [Xen-devel] [PATCH] Fix xenconsole after aborted save

To: Jiri Denemark <jdenemar@xxxxxxxxxx>, Gerd Hoffmann <kraxel@xxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] Fix xenconsole after aborted save
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Mon, 20 Apr 2009 15:41:17 +0100
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On 20/04/2009 15:04, "Jiri Denemark" <jdenemar@xxxxxxxxxx> wrote:

>>> This patch modifies xenconsoled to check current status of open event
>>> channels
>>> and rebind them if necessary.
>> close() + open() is the sledge hammer approach (will work though).  Just
>> unbind(local_port) should be enough.
> It doesn't close() and open(), it just calls xc_evtchn_bind_interdomain() in
> case the event channel is unbound. The close() + open() combination was there
> before... I haven't touched that code except for skipping it when only rebind
> is required.

And actually that is a bug, since you will leak the old dom->local_port. I
checked in an alternative patch as c/s 19561, so please take a look and test
that resolves your issue.

Another thing to note is I think this problem can only occur if the domU
does not support suspend cancellation (advertised as SUSPEND_CANCEL in
kernel elf notes -- see xen/xend/XendDomainInfo.py:resumeDomain()). Your
kernels should support that feature -- suspend cancellation (a.k.a. Resume)
is very likely to be hit-or-miss without it!

 -- Keir

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