reload cni network config if has fs change events

With go RWMutex design, no goroutine should expect to be able to
acquire a read lock until the read lock has been released, if one
goroutine call lock.

The original design is to reload cni network config on every single
Status CRI gRPC call. If one RunPodSandbox request holds read lock
to allocate IP for too long, all other RunPodSandbox/StopPodSandbox
requests will wait for the RunPodSandbox request to release read lock.
And the Status CRI call will fail and kubelet becomes NOTReady.

Reload cni network config at every single Status CRI call is not
necessary and also brings NOTReady situation. To lower the possibility
of NOTReady, CRI will reload cni network config if there is any valid fs
change events from the cni network config dir.

Signed-off-by: Wei Fu <fuweid89@gmail.com>

pkg/server/service_unix.go

@@ -60,11 +60,6 @@ func (c *criService) initPlatform() error {
 		return errors.Wrap(err, "failed to initialize cni")
 	}
 
-	// Try to load the config if it exists. Just log the error if load fails
-	// This is not disruptive for containerd to panic
-	if err := c.netPlugin.Load(c.cniLoadOptions()...); err != nil {
-		logrus.WithError(err).Error("Failed to load cni during init, please check CRI plugin status before setting up network for pods")
-	}
 	return nil
 }