[libvirt] [PATCHv2 8/9] network: restart radvd/dnsmasq if needed when libvirtd is restarted

[Daniel Veillard]

On Tue, Sep 18, 2012 at 03:39:04AM -0400, Laine Stump wrote:
> A user on IRC had accidentally killed all of his libvirt-started
> dnsmasq instances (due to a buggy dnsmasq service script in Fedora
> 16), and had hoped that libvirtd would notice this on restart and
> reload all the dnsmasq daemons (as it does with iptables
> rules). Unfortunately this was not the case - as long as the network
> object had a pid registered for dnsmasq and/or radvd, it assumed that
> the processes were running.
> 
> This patch takes advantage of the new utility functions in
> bridge_driver.c to do a "refresh" of all radvd and dnsmasq processes
> started by libvirt each time libvirtd is restarted - this function
> attempts to do a SIGHUP of each existing process, and if that fails,
> it restarts the process, rebuilding all the associated config files
> and commandline parameters in the process. This normally has no
> effect, but will be useful in solving the occasional "odd situation"
> without needing to take the drastic step of destroying/re-starting the
> network.
> ---
>  src/network/bridge_driver.c | 34 ++++++++++++++++++++++++++++++++++
>  1 file changed, 34 insertions(+)
> 
> diff --git a/src/network/bridge_driver.c b/src/network/bridge_driver.c
> index 252c964..0e38016 100644
> --- a/src/network/bridge_driver.c
> +++ b/src/network/bridge_driver.c
> @@ -117,6 +117,7 @@ static int networkShutdownNetworkExternal(struct network_driver *driver,
>                                          virNetworkObjPtr network);
>  
>  static void networkReloadIptablesRules(struct network_driver *driver);
> +static void networkRefreshDaemons(struct network_driver *driver);
>  
>  static struct network_driver *driverState = NULL;
>  
> @@ -344,6 +345,7 @@ networkStartup(int privileged) {
>  
>      networkFindActiveConfigs(driverState);
>      networkReloadIptablesRules(driverState);
> +    networkRefreshDaemons(driverState);
>      networkAutostartConfigs(driverState);
>  
>      networkDriverUnlock(driverState);
> @@ -404,6 +406,7 @@ networkReload(void) {
>                               driverState->networkConfigDir,
>                               driverState->networkAutostartDir);
>      networkReloadIptablesRules(driverState);
> +    networkRefreshDaemons(driverState);
>      networkAutostartConfigs(driverState);
>      networkDriverUnlock(driverState);
>      return 0;
> @@ -1210,6 +1213,37 @@ networkRestartRadvd(virNetworkObjPtr network)
>  }
>  #endif /* #if 0 */
>  
> +/* SIGHUP/restart any dnsmasq or radvd daemons.
> + * This should be called when libvirtd is restarted.
> + */
> +static void
> +networkRefreshDaemons(struct network_driver *driver)
> +{
> +    unsigned int i;
> +
> +    VIR_INFO("Refreshing network daemons");
> +
> +    for (i = 0 ; i < driver->networks.count ; i++) {
> +        virNetworkObjPtr network = driver->networks.objs[i];
> +
> +        virNetworkObjLock(network);
> +        if (virNetworkObjIsActive(network) &&
> +            ((network->def->forwardType == VIR_NETWORK_FORWARD_NONE) ||
> +             (network->def->forwardType == VIR_NETWORK_FORWARD_NAT) ||
> +             (network->def->forwardType == VIR_NETWORK_FORWARD_ROUTE))) {
> +            /* Only the three L3 network types that are configured by
> +             * libvirt will have a dnsmasq or radvd daemon associated
> +             * with them.  Here we send a SIGHUP to an existing
> +             * dnsmasq and/or radvd, or restart them if they've
> +             * disappeared.
> +             */
> +            networkRefreshDhcpDaemon(network);
> +            networkRefreshRadvd(network);
> +        }
> +        virNetworkObjUnlock(network);
> +    }
> +}
> +
>  static int
>  networkAddMasqueradingIptablesRules(struct network_driver *driver,
>                                      virNetworkObjPtr network,

  ACK, sounds simple and useful, hopefully there is no side effect to
the HUP'ed daemons.

Daniel

-- 
Daniel Veillard      | libxml Gnome XML XSLT toolkit  http://xmlsoft.org/
daniel at veillard.com  | Rpmfind RPM search engine http://rpmfind.net/
http://veillard.com/ | virtualization library  http://libvirt.org/