net: selftest: add test for netdev netlink queue-get API

Add a selftest for netdev generic netlink. For now there is only a
single test that exercises the `queue-get` API.

The test works with netdevsim by default or with a real device by
setting NETIF.

Add a timeout param to cmd() since ethtool -L can take a long time on
real devices.

Signed-off-by: David Wei <dw@davidwei.uk>
Link: https://lore.kernel.org/r/20240507163228.2066817-3-dw@davidwei.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/drivers/net/Makefile

@@ -4,6 +4,7 @@ TEST_INCLUDES := $(wildcard lib/py/*.py)
 
 TEST_PROGS := \
 	ping.py \
+	queues.py \
 	stats.py \
 # end of TEST_PROGS
 

tools/testing/selftests/drivers/net/lib/py/env.py

@@ -36,7 +36,7 @@ class NetDrvEnv:
     """
     Class for a single NIC / host env, with no remote end
     """
-    def __init__(self, src_path):
+    def __init__(self, src_path, **kwargs):
         self._ns = None
 
         self.env = _load_env_file(src_path)
@@ -44,11 +44,13 @@ class NetDrvEnv:
         if 'NETIF' in self.env:
             self.dev = ip("link show dev " + self.env['NETIF'], json=True)[0]
         else:
-            self._ns = NetdevSimDev()
+            self._ns = NetdevSimDev(**kwargs)
             self.dev = self._ns.nsims[0].dev
         self.ifindex = self.dev['ifindex']
 
     def __enter__(self):
+        ip(f"link set dev {self.dev['ifname']} up")
+
         return self
 
     def __exit__(self, ex_type, ex_value, ex_tb):

tools/testing/selftests/drivers/net/queues.py

@@ -0,0 +1,66 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+
+from lib.py import ksft_run, ksft_exit, ksft_eq, KsftSkipEx
+from lib.py import EthtoolFamily, NetdevFamily
+from lib.py import NetDrvEnv
+from lib.py import cmd
+import glob
+
+
+def sys_get_queues(ifname) -> int:
+    folders = glob.glob(f'/sys/class/net/{ifname}/queues/rx-*')
+    return len(folders)
+
+
+def nl_get_queues(cfg, nl):
+    queues = nl.queue_get({'ifindex': cfg.ifindex}, dump=True)
+    if queues:
+        return len([q for q in queues if q['type'] == 'rx'])
+    return None
+
+
+def get_queues(cfg, nl) -> None:
+    queues = nl_get_queues(cfg, nl)
+    if not queues:
+        raise KsftSkipEx('queue-get not supported by device')
+
+    expected = sys_get_queues(cfg.dev['ifname'])
+    ksft_eq(queues, expected)
+
+
+def addremove_queues(cfg, nl) -> None:
+    queues = nl_get_queues(cfg, nl)
+    if not queues:
+        raise KsftSkipEx('queue-get not supported by device')
+
+    curr_queues = sys_get_queues(cfg.dev['ifname'])
+    if curr_queues == 1:
+        raise KsftSkipEx('cannot decrement queue: already at 1')
+
+    netnl = EthtoolFamily()
+    channels = netnl.channels_get({'header': {'dev-index': cfg.ifindex}})
+    if channels['combined-count'] == 0:
+        rx_type = 'rx'
+    else:
+        rx_type = 'combined'
+
+    expected = curr_queues - 1
+    cmd(f"ethtool -L {cfg.dev['ifname']} {rx_type} {expected}", timeout=10)
+    queues = nl_get_queues(cfg, nl)
+    ksft_eq(queues, expected)
+
+    expected = curr_queues
+    cmd(f"ethtool -L {cfg.dev['ifname']} {rx_type} {expected}", timeout=10)
+    queues = nl_get_queues(cfg, nl)
+    ksft_eq(queues, expected)
+
+
+def main() -> None:
+    with NetDrvEnv(__file__, queue_count=3) as cfg:
+        ksft_run([get_queues, addremove_queues], args=(cfg, NetdevFamily()))
+    ksft_exit()
+
+
+if __name__ == "__main__":
+    main()

tools/testing/selftests/net/lib/py/nsim.py

@@ -49,7 +49,7 @@ class NetdevSimDev:
         with open(fullpath, "w") as f:
             f.write(val)
 
-    def __init__(self, port_count=1, ns=None):
+    def __init__(self, port_count=1, queue_count=1, ns=None):
         # nsim will spawn in init_net, we'll set to actual ns once we switch it there
         self.ns = None
 
@@ -59,7 +59,7 @@ class NetdevSimDev:
         addr = random.randrange(1 << 15)
         while True:
             try:
-                self.ctrl_write("new_device", "%u %u" % (addr, port_count))
+                self.ctrl_write("new_device", "%u %u %u" % (addr, port_count, queue_count))
             except OSError as e:
                 if e.errno == errno.ENOSPC:
                     addr = random.randrange(1 << 15)

tools/testing/selftests/net/lib/py/utils.py

@@ -8,7 +8,7 @@ import time
 
 
 class cmd:
-    def __init__(self, comm, shell=True, fail=True, ns=None, background=False, host=None):
+    def __init__(self, comm, shell=True, fail=True, ns=None, background=False, host=None, timeout=5):
         if ns:
             comm = f'ip netns exec {ns} ' + comm
 
@@ -23,15 +23,15 @@ class cmd:
             self.proc = subprocess.Popen(comm, shell=shell, stdout=subprocess.PIPE,
                                          stderr=subprocess.PIPE)
         if not background:
-            self.process(terminate=False, fail=fail)
+            self.process(terminate=False, fail=fail, timeout=timeout)
 
-    def process(self, terminate=True, fail=None):
+    def process(self, terminate=True, fail=None, timeout=5):
         if fail is None:
             fail = not terminate
 
         if terminate:
             self.proc.terminate()
-        stdout, stderr = self.proc.communicate(timeout=5)
+        stdout, stderr = self.proc.communicate(timeout)
         self.stdout = stdout.decode("utf-8")
         self.stderr = stderr.decode("utf-8")
         self.proc.stdout.close()