[libvirt] [PATCH] qemuProcessReconnect: Fill in pid file path

Daniel P. Berrange berrange at redhat.com
Tue Mar 3 11:27:00 UTC 2015


On Tue, Mar 03, 2015 at 11:56:37AM +0100, Michal Privoznik wrote:
> https://bugzilla.redhat.com/show_bug.cgi?id=1197600
> 
> So, libvirt uses pid file to track pid of started qemus. Whenever
> a domain is started, its pid is put into corresponding pid file.
> The pid file path is generated based on domain name and stored
> into domain object internals. However, it's not stored in the
> status XML and therefore lost on daemon restarts. Hence, later,
> when domain is being shut down, the daemon does not know which
> pid file to unlink, and the correct pid file is left behind. To
> avoid this, lets generate the pid file path again in
> qemuProcessReconnect().
> 
> Reported-by: Luyao Huang <lhuang at redhat.com>
> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
> ---
>  src/qemu/qemu_process.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
> index 7ce6115..e77616a 100644
> --- a/src/qemu/qemu_process.c
> +++ b/src/qemu/qemu_process.c
> @@ -3762,6 +3762,13 @@ qemuProcessReconnect(void *opaque)
>      cfg = virQEMUDriverGetConfig(driver);
>      priv = obj->privateData;
>  
> +    /* XXX If we ever gonna change pid file pattern, come up with
> +     * some intelligence here to deal with old paths. */

We already have arbitrary patterns due to virDomainQEMUAttach() which can
talk to an existing QEMU.  We should save the pidfile pattern in the status
XML file so we remember it. For upgrades from existing deployments we would
have to cope with the status XML not having pidfile, and so fallback to
building it again.

> +    if (!(priv->pidfile = virPidFileBuildPath(cfg->stateDir, obj->def->name))) {
> +        virReportSystemError(errno, "%s", _("Failed to build pidfile path."));
> +        goto killvm;
> +    }
> +
>      if (qemuDomainObjBeginJob(driver, obj, QEMU_JOB_MODIFY) < 0)
>          goto killvm;


Regards,
Daniel
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