New subject: [PATCH] Controller.Machine: fix moving a device to a network namespace

13 May 2021

When a device is moved to a network namespace an RTM_NEWLINK netlink
message is generated and handled by InterfaceManager. The InterfaceManager
creates a new instance of a generic Device class instead of a specific device
class (e.g. VethDevice). This device also remains in disabled state so
no actions or configurations can be made.
This patch fixes that by following changes.
The InterfaceManager is extended with remap_device() method that
creates a new instance of the specific device class that replaces the
generic Device instance.
The SlaveMethods are extended with remap_device() method that serves as
an rpc interface for calling InterfaceManager's method from the
Controller.
The Machine.remote_device_set_netns() method is updated to include an
explicit rpc_call to remap the device to proper type.
Signed-off-by: Jan Tluka jtluka@redhat.com
---
 lnst/Controller/Machine.py     | 10 ++++++++++
 lnst/Slave/InterfaceManager.py | 14 ++++++++++++++
 lnst/Slave/NetTestSlave.py     |  3 +++
 3 files changed, 27 insertions(+)

diff --git a/lnst/Controller/Machine.py b/lnst/Controller/Machine.py
index 3bee2a55..a4c724ba 100644
--- a/lnst/Controller/Machine.py
+++ b/lnst/Controller/Machine.py
@@ -141,6 +141,16 @@ class Machine(object):
def remote_device_set_netns(self, dev, dst, src):
         self.rpc_call("set_dev_netns", dev, dst.name, netns=src)
+        dev_clsname = dev._dev_cls.__name__
+        dev_args = dev._dev_args
+        dev_kwargs = dev._dev_kwargs
+
+        self.rpc_call("remap_device",
+                dev.ifindex,
+                clsname=dev_clsname,
+                args=dev_args,
+                kwargs=dev_kwargs,
+                netns=dst)
def remote_device_method(self, index, method_name, args, kwargs, netns):
         config_res = DeviceMethodCallResult(
diff --git a/lnst/Slave/InterfaceManager.py b/lnst/Slave/InterfaceManager.py
index 221d386f..4a653dd7 100644
--- a/lnst/Slave/InterfaceManager.py
+++ b/lnst/Slave/InterfaceManager.py
@@ -221,6 +221,20 @@ class InterfaceManager(object):
         else:
             raise DeviceError("Device creation failed")
+    def remap_device(self, ifindex, clsname, args=[], kwargs={}):
+        devcls = self._device_classes[clsname]
+        old_device = self.get_device(ifindex)
+        kwargs["name"] = old_device.name
+
+        try:
+            remapped_device = devcls(self, *args, **kwargs)
+        except KeyError as e:
+            raise DeviceConfigError("%s is a mandatory argument" % e)
+        remapped_device._bulk_enabled = False
+        remapped_device.ifindex = ifindex
+        self.replace_dev(ifindex, remapped_device)
+        self.rescan_devices()
+
     def replace_dev(self, if_id, dev):
         del self._devices[if_id]
         self._devices[if_id] = dev
diff --git a/lnst/Slave/NetTestSlave.py b/lnst/Slave/NetTestSlave.py
index d3ff90bf..2164b9c5 100644
--- a/lnst/Slave/NetTestSlave.py
+++ b/lnst/Slave/NetTestSlave.py
@@ -646,6 +646,9 @@ class SlaveMethods:
         #TODO check if device appeared in the destination namespace
         return True
+    def remap_device(self, ifindex, clsname, args=[], kwargs={}):
+        self._if_manager.remap_device(ifindex, clsname, args, kwargs)
+
     # def return_if_netns(self, if_id):
         # device = self._if_manager.get_mapped_device(if_id)
         # if device.get_netns() == None:
-- 
2.26.3

    