selftests: tc-testing: rework namespaces and devices setup

As mentioned in the TC Workshop 0x17, our recent changes to tdc broke
downstream CI systems like tuxsuite. The issue is the classic problem
with rcu/workqueue objects where you can miss them if not enough wall time
has passed. The latter is subjective to the system and kernel config,
in my machine could be nanoseconds while in another could be microseconds
or more.

In order to make the suite deterministic, poll for the existence
of the objects in a reasonable manner. Talking netlink directly is the
the best solution in order to avoid paying the cost of multiple
'fork()' calls, so introduce a netlink based setup routine using
pyroute2. We leave the iproute2 one as a fallback when pyroute2 is not
available.

Also rework the iproute2 side to mimic the netlink routine where it
creates DEV0 as the peer of DEV1 and moves DEV1 into the net namespace.
This way when the namespace is deleted DEV0 is also deleted
automatically, leaving no margin for resource leaks.

Another bonus of this change is that our setup time sped up by a factor
of 2 when using netlink.

Signed-off-by: Pedro Tammela <pctammela@mojatatu.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: tammela

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

@@ -9,6 +9,14 @@
 
 from tdc_config import *
 
+try:
+    from pyroute2 import netns
+    from pyroute2 import IPRoute
+    netlink = True
+except ImportError:
+    netlink = False
+    print("!!! Consider installing pyroute2 !!!")
+
 def prepare_suite(obj, test):
     original = obj.args.NAMES
 
@@ -28,7 +36,10 @@ def prepare_suite(obj, test):
     shadow['DEV2'] = original['DEV2']
     obj.args.NAMES = shadow
 
-    obj._ns_create()
+    if netlink == True:
+        obj._nl_ns_create()
+    else:
+        obj._ns_create()
 
     # Make sure the netns is visible in the fs
     while True:
@@ -67,7 +78,6 @@ def pre_case(self, caseinfo, test_skip):
         if test_skip:
             return
 
-
     def post_case(self):
         if self.args.verbose:
             print('{}.post_case'.format(self.sub_class))
@@ -119,34 +129,55 @@ def adjust_command(self, stage, command):
             print('adjust_command:  return command [{}]'.format(command))
         return command
 
-    def _ports_create_cmds(self):
-        cmds = []
+    def _nl_ns_create(self):
+        ns = self.args.NAMES["NS"];
+        dev0 = self.args.NAMES["DEV0"];
+        dev1 = self.args.NAMES["DEV1"];
+        dummy = self.args.NAMES["DUMMY"];
 
-        cmds.append(self._replace_keywords('link add $DEV0 type veth peer name $DEV1'))
-        cmds.append(self._replace_keywords('link set $DEV0 up'))
-        cmds.append(self._replace_keywords('link add $DUMMY type dummy'))
-
-        return cmds
-
-    def _ports_create(self):
-        self._exec_cmd_batched('pre', self._ports_create_cmds())
-
-    def _ports_destroy_cmd(self):
-        return self._replace_keywords('link del $DEV0')
-
-    def _ports_destroy(self):
-        self._exec_cmd('post', self._ports_destroy_cmd())
+        if self.args.verbose:
+            print('{}._nl_ns_create'.format(self.sub_class))
+
+        netns.create(ns)
+        netns.pushns(newns=ns)
+        with IPRoute() as ip:
+            ip.link('add', ifname=dev1, kind='veth', peer={'ifname': dev0, 'net_ns_fd':'/proc/1/ns/net'})
+            ip.link('add', ifname=dummy, kind='dummy')
+            while True:
+                try:
+                    dev1_idx = ip.link_lookup(ifname=dev1)[0]
+                    dummy_idx = ip.link_lookup(ifname=dummy)[0]
+                    ip.link('set', index=dev1_idx, state='up')
+                    ip.link('set', index=dummy_idx, state='up')
+                    break
+                except:
+                    time.sleep(0.1)
+                    continue
+        netns.popns()
+
+        with IPRoute() as ip:
+            while True:
+                try:
+                    dev0_idx = ip.link_lookup(ifname=dev0)[0]
+                    ip.link('set', index=dev0_idx, state='up')
+                    break
+                except:
+                    time.sleep(0.1)
+                    continue
 
     def _ns_create_cmds(self):
         cmds = []
 
         ns = self.args.NAMES['NS']
 
         cmds.append(self._replace_keywords('netns add {}'.format(ns)))
+        cmds.append(self._replace_keywords('link add $DEV1 type veth peer name $DEV0'))
         cmds.append(self._replace_keywords('link set $DEV1 netns {}'.format(ns)))
+        cmds.append(self._replace_keywords('link add $DUMMY type dummy'.format(ns)))
         cmds.append(self._replace_keywords('link set $DUMMY netns {}'.format(ns)))
         cmds.append(self._replace_keywords('netns exec {} $IP link set $DEV1 up'.format(ns)))
         cmds.append(self._replace_keywords('netns exec {} $IP link set $DUMMY up'.format(ns)))
+        cmds.append(self._replace_keywords('link set $DEV0 up'.format(ns)))
 
         if self.args.device:
             cmds.append(self._replace_keywords('link set $DEV2 netns {}'.format(ns)))
@@ -159,7 +190,6 @@ 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()
         self._exec_cmd_batched('pre', self._ns_create_cmds())
 
     def _ns_destroy_cmd(self):
@@ -171,7 +201,6 @@ def _ns_destroy(self):
         devices as well)
         '''
         self._exec_cmd('post', self._ns_destroy_cmd())
-        self._ports_destroy()
 
     @cached_property
     def _proc(self):