[libvirt PATCH] nwfilter: spawn thread for reloading on firewalld trigger

[Erik Skultety]

On Fri, Apr 01, 2022 at 10:28:54AM +0100, Daniel P. Berrangé wrote:
> When firewalld is restarted or has its rules reloaded, we trigger a
> reload of the nwfilter driver. This is done directly in the main
> event loop thread which is a bad idea.
> 
> In a previous commit we fixed a actual deadlock problem with the
> virStateReload API, when triggered from SIGHUP:
> 
> commit 33c6eb9689eb51dfe31dd05b24b3b6b1c948c267
> Author: Jim Fehlig <jfehlig at suse.com>
> Date:   Thu Mar 8 15:04:48 2018 -0700
> 
>     libvirtd: fix potential deadlock when reloading
> 
> The same deadlock problem previously existed with the firewalld reload
> trigger, however, today it is not quite so series. The QEMU driver uses
> a private event thread for each VM, so the particular deadlock would
> not occur. None the less during the time the filters are reloading all
> use of the event loop is blocked, which prevents APIs being serviced.
> 
> Signed-off-by: Daniel P. Berrangé <berrange at redhat.com>
> ---
Reviewed-by: Erik Skultety <eskultet at redhat.com>