[libvirt] [PATCH v3] qemu: Ignore nwfilter binding instantiation issues during reconnect

[John Ferlan]

ping?

Tks,

John

On 08/24/2018 10:02 AM, John Ferlan wrote:
> https://bugzilla.redhat.com/show_bug.cgi?id=1607202
> 
> It's essentially stated in the nwfilterBindingDelete that we
> will allow the admin to shoot themselves in the foot by deleting
> the nwfilter binding which then allows them to undefine the
> nwfilter that is in use for the running guest...
> 
> However, by allowing this we cause a problem for libvirtd
> restart reconnect processing which would then try to recreate
> the missing binding attempting to use the deleted filter
> resulting in an error and thus shutting the guest down.
> 
> So rather than keep adding virDomainConfNWFilterInstantiate
> flags to "ignore" specific error conditions, modify the logic
> to ignore, but VIR_WARN errors other than ignoreExists. This
> will at least allow the guest to not shutdown for only nwfilter
> binding errors that we can now perhaps recover from since we
> have the binding create/delete capability.
> 
> Signed-off-by: John Ferlan <jferlan at redhat.com>
> ---
> 
>  v2: https://www.redhat.com/archives/libvir-list/2018-August/msg01567.html
> 
>  Differences to v2.  Leave the ignoreExists bool, but just allow and
>  VIR_WARN other errors from virDomainConfNWFilterInstantiate. Continue
>  processing all filters from error point too.
> 
>  src/qemu/qemu_process.c | 24 ++++++++++++++++--------
>  1 file changed, 16 insertions(+), 8 deletions(-)
> 
> diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
> index ab749389ee..61a277f468 100644
> --- a/src/qemu/qemu_process.c
> +++ b/src/qemu/qemu_process.c
> @@ -3160,20 +3160,29 @@ qemuProcessNotifyNets(virDomainDefPtr def)
>      }
>  }
>  
> -static int
> -qemuProcessFiltersInstantiate(virDomainDefPtr def, bool ignoreExists)
> +/* Attempt to instantiate the filters. Ignore failures because it's
> + * possible that someone deleted a filter binding and the associated
> + * filter while the guest was running and we don't want that action
> + * to cause failure to keep the guest running during the reconnection
> + * processing. Nor do we necessarily want other failures to do the
> + * same. We'll just log the error conditions other than of course
> + * ignoreExists possibility (e.g. the true flag) */
> +static void
> +qemuProcessFiltersInstantiate(virDomainDefPtr def)
>  {
>      size_t i;
>  
>      for (i = 0; i < def->nnets; i++) {
>          virDomainNetDefPtr net = def->nets[i];
>          if ((net->filter) && (net->ifname)) {
> -            if (virDomainConfNWFilterInstantiate(def->name, def->uuid, net, ignoreExists) < 0)
> -                return 1;
> +            if (virDomainConfNWFilterInstantiate(def->name, def->uuid, net,
> +                                                 true) < 0) {
> +                VIR_WARN("filter '%s' instantiation for '%s' failed '%s'",
> +                         net->filter, net->ifname, virGetLastErrorMessage());
> +                virResetLastError();
> +            }
>          }
>      }
> -
> -    return 0;
>  }
>  
>  static int
> @@ -7892,8 +7901,7 @@ qemuProcessReconnect(void *opaque)
>  
>      qemuProcessNotifyNets(obj->def);
>  
> -    if (qemuProcessFiltersInstantiate(obj->def, true))
> -        goto error;
> +    qemuProcessFiltersInstantiate(obj->def);
>  
>      if (qemuProcessRefreshDisks(driver, obj, QEMU_ASYNC_JOB_NONE) < 0)
>          goto error;
>