From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Cooper <andrew.cooper3@citrix.com>
Subject: Re: [PATCH v2 13/13] tools: don't stop xenstore domain
 when stopping dom0
Date: Fri, 18 Dec 2015 14:42:11 +0000
Message-ID: <56741B43.3040800@citrix.com>
References: <1450444471-6454-1-git-send-email-jgross@suse.com>
	<1450444471-6454-14-git-send-email-jgross@suse.com>
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To: Juergen Gross <jgross@suse.com>, xen-devel@lists.xen.org, Ian.Campbell@citrix.com, ian.jackson@eu.citrix.com, stefano.stabellini@eu.citrix.com, wei.liu2@citrix.com, dgdegra@tycho.nsa.gov
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On 18/12/15 13:14, Juergen Gross wrote:
> When restarting or shutting down dom0 the xendomains script tries to
> stop all other domains. Don't do this for the xenstore domain, as it
> might survive a dom0 reboot in the future.
>
> The same applies to xl shutdown --all.
>
> Signed-off-by: Juergen Gross <jgross@suse.com>
> ---
>  tools/hotplug/Linux/xendomains.in | 17 +++++++++++++++++
>  tools/libxl/xl_cmdimpl.c          | 19 +++++++++++++++----
>  2 files changed, 32 insertions(+), 4 deletions(-)
>
> diff --git a/tools/hotplug/Linux/xendomains.in b/tools/hotplug/Linux/xendomains.in
> index dfe0b33..70b7f16 100644
> --- a/tools/hotplug/Linux/xendomains.in
> +++ b/tools/hotplug/Linux/xendomains.in
> @@ -196,6 +196,17 @@ rdnames()
>      done
>  }
>  
> +# set xenstore domain id (or 0 if no xenstore domain)
> +get_xsdomid()

A get/set mismatch.

> +{
> +    ${bindir}/xenstore-exists /tool/xenstored/domid
> +    if test $? -ne 0; then
> +        XS_DOMID=0
> +    else
> +        XS_DOMID=`${bindir}/xenstore-read /tool/xenstored/domid`
> +    fi

This is racy.  Can't you use a failure of xenstore-read as a signal that
the key doesn't exist?

~Andrew