Merge branch 'ynl-tests'

Jakub Kicinski says:

====================
selftests: net: groundwork for YNL-based tests

Currently the options for writing networking tests are C, bash or
some mix of the two. YAML/Netlink gives us the ability to easily
interface with Netlink in higher level laguages. In particular,
there is a Python library already available in tree, under tools/net.
Add the scaffolding which allows writing tests using this library.

The "scaffolding" is needed because the library lives under
tools/net and uses YAML files from under Documentation/.
So we need a small amount of glue code to find those things
and add them to TEST_FILES.

This series adds both a basic SW sanity test and driver
test which can be run against netdevsim or a real device.
When I develop core code I usually test with netdevsim,
then a real device, and then a backport to Meta's kernel.
Because of the lack of integration, until now I had
to throw away the (YNL-based) test script and netdevsim code.

Running tests in tree directly:

 $ ./tools/testing/selftests/net/nl_netdev.py
 KTAP version 1
 1..2
 ok 1 nl_netdev.empty_check
 ok 2 nl_netdev.lo_check
 # Totals: pass:2 fail:0 xfail:0 xpass:0 skip:0 error:0

in tree via make:

 $ make -C tools/testing/selftests/ TARGETS=net \
	TEST_PROGS=nl_netdev.py TEST_GEN_PROGS="" run_tests
  [ ... ]

and installed externally, all seem to work:

 $ make -C tools/testing/selftests/ TARGETS=net \
	install INSTALL_PATH=/tmp/ksft-net
 $ /tmp/ksft-net/run_kselftest.sh -t net:nl_netdev.py
  [ ... ]

For driver tests I followed the lead of net/forwarding and
get the device name from env and/or a config file.

v3:
 - fix up netdevsim C
 - various small nits in other patches (see changelog in patches)
v2: https://lore.kernel.org/all/20240403023426.1762996-1-kuba@kernel.org/
 - don't add to TARGETS, create a deperate variable with deps
 - support and use with
 - support and use passing arguments to tests
v1: https://lore.kernel.org/all/20240402010520.1209517-1-kuba@kernel.org/
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 115 insertions, 0 deletions

diff --git a/tools/testing/selftests/net/lib/py/nsim.py b/tools/testing/selftests/net/lib/py/nsim.py
new file mode 100644
index 000000000000..b2d696e12805
--- /dev/null
+++ b/tools/testing/selftests/net/lib/py/nsim.py
@@ -0,0 +1,115 @@
+# SPDX-License-Identifier: GPL-2.0
+
+import json
+import os
+import random
+import re
+import time
+from .utils import cmd, ip
+
+
+class NetdevSim:
+    """
+    Class for netdevsim netdevice and its attributes.
+    """
+
+    def __init__(self, nsimdev, port_index, ifname, ns=None):
+        # In case udev renamed the netdev to according to new schema,
+        # check if the name matches the port_index.
+        nsimnamere = re.compile(r"eni\d+np(\d+)")
+        match = nsimnamere.match(ifname)
+        if match and int(match.groups()[0]) != port_index + 1:
+            raise Exception("netdevice name mismatches the expected one")
+
+        self.nsimdev = nsimdev
+        self.port_index = port_index
+        ret = ip("-j link show dev %s" % ifname, ns=ns)
+        self.dev = json.loads(ret.stdout)[0]
+
+    def dfs_write(self, path, val):
+        self.nsimdev.dfs_write(f'ports/{self.port_index}/' + path, val)
+
+
+class NetdevSimDev:
+    """
+    Class for netdevsim bus device and its attributes.
+    """
+    @staticmethod
+    def ctrl_write(path, val):
+        fullpath = os.path.join("/sys/bus/netdevsim/", path)
+        with open(fullpath, "w") as f:
+            f.write(val)
+
+    def dfs_write(self, path, val):
+        fullpath = os.path.join(f"/sys/kernel/debug/netdevsim/netdevsim{self.addr}/", path)
+        with open(fullpath, "w") as f:
+            f.write(val)
+
+    def __init__(self, port_count=1, ns=None):
+        # nsim will spawn in init_net, we'll set to actual ns once we switch it there
+        self.ns = None
+
+        if not os.path.exists("/sys/bus/netdevsim"):
+            cmd("modprobe netdevsim")
+
+        addr = random.randrange(1 << 15)
+        while True:
+            try:
+                self.ctrl_write("new_device", "%u %u" % (addr, port_count))
+            except OSError as e:
+                if e.errno == errno.ENOSPC:
+                    addr = random.randrange(1 << 15)
+                    continue
+                raise e
+            break
+        self.addr = addr
+
+        # As probe of netdevsim device might happen from a workqueue,
+        # so wait here until all netdevs appear.
+        self.wait_for_netdevs(port_count)
+
+        if ns:
+            cmd(f"devlink dev reload netdevsim/netdevsim{addr} netns {ns.name}")
+            self.ns = ns
+
+        cmd("udevadm settle", ns=self.ns)
+        ifnames = self.get_ifnames()
+
+        self.dfs_dir = "/sys/kernel/debug/netdevsim/netdevsim%u/" % addr
+
+        self.nsims = []
+        for port_index in range(port_count):
+            self.nsims.append(NetdevSim(self, port_index, ifnames[port_index],
+                                        ns=ns))
+
+    def get_ifnames(self):
+        ifnames = []
+        listdir = cmd(f"ls /sys/bus/netdevsim/devices/netdevsim{self.addr}/net/",
+                      ns=self.ns).stdout.split()
+        for ifname in listdir:
+            ifnames.append(ifname)
+        ifnames.sort()
+        return ifnames
+
+    def wait_for_netdevs(self, port_count):
+        timeout = 5
+        timeout_start = time.time()
+
+        while True:
+            try:
+                ifnames = self.get_ifnames()
+            except FileNotFoundError as e:
+                ifnames = []
+            if len(ifnames) == port_count:
+                break
+            if time.time() < timeout_start + timeout:
+                continue
+            raise Exception("netdevices did not appear within timeout")
+
+    def remove(self):
+        self.ctrl_write("del_device", "%u" % (self.addr, ))
+
+    def remove_nsim(self, nsim):
+        self.nsims.remove(nsim)
+        self.ctrl_write("devices/netdevsim%u/del_port" % (self.addr, ),
+                        "%u" % (nsim.port_index, ))