tc-testing: Restore original behaviour for namespaces in tdc

This patch restores the original behaviour for tdc prior to the
introduction of the plugin system, where the network namespace
functionality was split from the main script.

It introduces the concept of required plugins for testcases,
and will automatically load any plugin that isn't already
enabled when said plugin is required by even one testcase.

Additionally, the -n option for the nsPlugin is deprecated
so the default action is to make use of the namespaces.
Instead, we introduce -N to not use them, but still create
the veth pair.

buildebpfPlugin's -B option is also deprecated.

If a test cases requires the features of a specific plugin
in order to pass, it should instead include a new key/value
pair describing plugin interactions:

        "plugins": {
                "requires": "buildebpfPlugin"
        },

A test case can have more than one required plugin: a list
can be inserted as the value for 'requires'.

Signed-off-by: Lucas Bates <lucasb@mojatatu.com>
Acked-by: Davide Caratti <dcaratti@redhat.com>
Tested-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/tc-testing/README

@@ -12,10 +12,10 @@ REQUIREMENTS
 *  Minimum Python version of 3.4. Earlier 3.X versions may work but are not
    guaranteed.
 
-*  The kernel must have network namespace support
+*  The kernel must have network namespace support if using nsPlugin
 
 *  The kernel must have veth support available, as a veth pair is created
-   prior to running the tests.
+   prior to running the tests when using nsPlugin.
 
 *  The kernel must have the appropriate infrastructure enabled to run all tdc
    unit tests. See the config file in this directory for minimum required
@@ -53,8 +53,12 @@ commands being tested must be run as root.  The code that enforces
 execution by root uid has been moved into a plugin (see PLUGIN
 ARCHITECTURE, below).
 
-If nsPlugin is linked, all tests are executed inside a network
-namespace to prevent conflicts within the host.
+Tests that use a network device should have nsPlugin.py listed as a
+requirement for that test. nsPlugin executes all commands within a
+network namespace and creates a veth pair which may be used in those test
+cases. To disable execution within the namespace, pass the -N option
+to tdc when starting a test run; the veth pair will still be created
+by the plugin.
 
 Running tdc without any arguments will run all tests. Refer to the section
 on command line arguments for more information, or run:
@@ -154,8 +158,8 @@ action:
 netns:
   options for nsPlugin (run commands in net namespace)
 
-  -n, --namespace
-                        Run commands in namespace as specified in tdc_config.py
+  -N, --no-namespace
+                        Do not run commands in a network namespace.
 
 valgrind:
   options for valgrindPlugin (run command under test under Valgrind)
@@ -171,7 +175,8 @@ was in the tdc.py script has been moved into the plugins.
 
 The plugins are in the directory plugin-lib.  The are executed from
 directory plugins.  Put symbolic links from plugins to plugin-lib,
-and name them according to the order you want them to run.
+and name them according to the order you want them to run. This is not
+necessary if a test case being run requires a specific plugin to work.
 
 Example:
 
@@ -223,7 +228,8 @@ directory:
   - rootPlugin.py:
       implements the enforcement of running as root
   - nsPlugin.py:
-      sets up a network namespace and runs all commands in that namespace
+      sets up a network namespace and runs all commands in that namespace,
+      while also setting up dummy devices to be used in testing.
   - valgrindPlugin.py
       runs each command in the execute stage under valgrind,
       and checks for leaks.

tools/testing/selftests/tc-testing/plugin-lib/buildebpfPlugin.py

@@ -34,8 +34,9 @@ def add_args(self, parser):
             'buildebpf',
             'options for buildebpfPlugin')
         self.argparser_group.add_argument(
-            '-B', '--buildebpf', action='store_true',
-            help='build eBPF programs')
+            '--nobuildebpf', action='store_false', default=True,
+            dest='buildebpf',
+            help='Don\'t build eBPF programs')
 
         return self.argparser
 

tools/testing/selftests/tc-testing/plugin-lib/nsPlugin.py

@@ -18,6 +18,8 @@ def pre_suite(self, testcount, testidlist):
 
         if self.args.namespace:
             self._ns_create()
+        else:
+            self._ports_create()
 
     def post_suite(self, index):
         '''run commands after test_runner goes into a test loop'''
@@ -27,15 +29,17 @@ def post_suite(self, index):
 
         if self.args.namespace:
             self._ns_destroy()
+        else:
+            self._ports_destroy()
 
     def add_args(self, parser):
         super().add_args(parser)
         self.argparser_group = self.argparser.add_argument_group(
             'netns',
             'options for nsPlugin(run commands in net namespace)')
         self.argparser_group.add_argument(
-            '-n', '--namespace', action='store_true',
-            help='Run commands in namespace')
+            '-N', '--no-namespace', action='store_false', default=True,
+            dest='namespace', help='Don\'t run commands in namespace')
         return self.argparser
 
     def adjust_command(self, stage, command):
@@ -73,20 +77,30 @@ def adjust_command(self, stage, command):
             print('adjust_command:  return command [{}]'.format(command))
         return command
 
+    def _ports_create(self):
+        cmd = 'ip link add $DEV0 type veth peer name $DEV1'
+        self._exec_cmd('pre', cmd)
+        cmd = 'ip link set $DEV0 up'
+        self._exec_cmd('pre', cmd)
+        if not self.args.namespace:
+            cmd = 'ip link set $DEV1 up'
+            self._exec_cmd('pre', cmd)
+
+    def _ports_destroy(self):
+        cmd = 'ip link del $DEV0'
+        self._exec_cmd('post', cmd)
+
     def _ns_create(self):
         '''
         Create the network namespace in which the tests will be run and set up
         the required network devices for it.
         '''
+        self._ports_create()
         if self.args.namespace:
             cmd = 'ip netns add {}'.format(self.args.NAMES['NS'])
             self._exec_cmd('pre', cmd)
-            cmd = 'ip link add $DEV0 type veth peer name $DEV1'
-            self._exec_cmd('pre', cmd)
             cmd = 'ip link set $DEV1 netns {}'.format(self.args.NAMES['NS'])
             self._exec_cmd('pre', cmd)
-            cmd = 'ip link set $DEV0 up'
-            self._exec_cmd('pre', cmd)
             cmd = 'ip -n {} link set $DEV1 up'.format(self.args.NAMES['NS'])
             self._exec_cmd('pre', cmd)
             if self.args.device:

tools/testing/selftests/tc-testing/tc-tests/actions/bpf.json

@@ -54,6 +54,9 @@
             "actions",
             "bpf"
         ],
+        "plugins": {
+                "requires": "buildebpfPlugin"
+        },
         "setup": [
             [
                 "$TC action flush action bpf",
@@ -78,6 +81,9 @@
             "actions",
             "bpf"
         ],
+        "plugins": {
+                "requires": "buildebpfPlugin"
+        },
         "setup": [
             [
                 "$TC action flush action bpf",