selftests/bpf: add offload test based on netdevsim

Add a test of BPF offload control path interfaces based on
just-added netdevsim driver.  Perform various checks of both
the stack and the expected driver behaviour.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Jakub Kicinski 2017-12-01 15:09:00 -08:00 коммит произвёл Daniel Borkmann
Родитель 31d3ad8329
Коммит 417ec26477
3 изменённых файлов: 691 добавлений и 2 удалений

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@ -17,9 +17,10 @@ TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test
TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o test_obj_id.o \ TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o test_obj_id.o \
test_pkt_md_access.o test_xdp_redirect.o test_xdp_meta.o sockmap_parse_prog.o \ test_pkt_md_access.o test_xdp_redirect.o test_xdp_meta.o sockmap_parse_prog.o \
sockmap_verdict_prog.o dev_cgroup.o sockmap_verdict_prog.o dev_cgroup.o sample_ret0.o
TEST_PROGS := test_kmod.sh test_xdp_redirect.sh test_xdp_meta.sh TEST_PROGS := test_kmod.sh test_xdp_redirect.sh test_xdp_meta.sh \
test_offload.py
include ../lib.mk include ../lib.mk

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@ -0,0 +1,7 @@
/* SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause) */
/* Sample program which should always load for testing control paths. */
int func()
{
return 0;
}

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@ -0,0 +1,681 @@
#!/usr/bin/python3
# Copyright (C) 2017 Netronome Systems, Inc.
#
# This software is licensed under the GNU General License Version 2,
# June 1991 as shown in the file COPYING in the top-level directory of this
# source tree.
#
# THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS"
# WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING,
# BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
# FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE
# OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME
# THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
from datetime import datetime
import argparse
import json
import os
import pprint
import subprocess
import time
logfile = None
log_level = 1
bpf_test_dir = os.path.dirname(os.path.realpath(__file__))
pp = pprint.PrettyPrinter()
devs = [] # devices we created for clean up
files = [] # files to be removed
def log_get_sec(level=0):
return "*" * (log_level + level)
def log_level_inc(add=1):
global log_level
log_level += add
def log_level_dec(sub=1):
global log_level
log_level -= sub
def log_level_set(level):
global log_level
log_level = level
def log(header, data, level=None):
"""
Output to an optional log.
"""
if logfile is None:
return
if level is not None:
log_level_set(level)
if not isinstance(data, str):
data = pp.pformat(data)
if len(header):
logfile.write("\n" + log_get_sec() + " ")
logfile.write(header)
if len(header) and len(data.strip()):
logfile.write("\n")
logfile.write(data)
def skip(cond, msg):
if not cond:
return
print("SKIP: " + msg)
log("SKIP: " + msg, "", level=1)
os.sys.exit(0)
def fail(cond, msg):
if not cond:
return
print("FAIL: " + msg)
log("FAIL: " + msg, "", level=1)
os.sys.exit(1)
def start_test(msg):
log(msg, "", level=1)
log_level_inc()
print(msg)
def cmd(cmd, shell=True, include_stderr=False, background=False, fail=True):
"""
Run a command in subprocess and return tuple of (retval, stdout);
optionally return stderr as well as third value.
"""
proc = subprocess.Popen(cmd, shell=shell, stdout=subprocess.PIPE,
stderr=subprocess.PIPE)
if background:
msg = "%s START: %s" % (log_get_sec(1),
datetime.now().strftime("%H:%M:%S.%f"))
log("BKG " + proc.args, msg)
return proc
return cmd_result(proc, include_stderr=include_stderr, fail=fail)
def cmd_result(proc, include_stderr=False, fail=False):
stdout, stderr = proc.communicate()
stdout = stdout.decode("utf-8")
stderr = stderr.decode("utf-8")
proc.stdout.close()
proc.stderr.close()
stderr = "\n" + stderr
if stderr[-1] == "\n":
stderr = stderr[:-1]
sec = log_get_sec(1)
log("CMD " + proc.args,
"RETCODE: %d\n%s STDOUT:\n%s%s STDERR:%s\n%s END: %s" %
(proc.returncode, sec, stdout, sec, stderr,
sec, datetime.now().strftime("%H:%M:%S.%f")))
if proc.returncode != 0 and fail:
if len(stderr) > 0 and stderr[-1] == "\n":
stderr = stderr[:-1]
raise Exception("Command failed: %s\n%s" % (proc.args, stderr))
if include_stderr:
return proc.returncode, stdout, stderr
else:
return proc.returncode, stdout
def rm(f):
cmd("rm -f %s" % (f))
if f in files:
files.remove(f)
def tool(name, args, flags, JSON=True, fail=True):
params = ""
if JSON:
params += "%s " % (flags["json"])
ret, out = cmd(name + " " + params + args, fail=fail)
if JSON and len(out.strip()) != 0:
return ret, json.loads(out)
else:
return ret, out
def bpftool(args, JSON=True, fail=True):
return tool("bpftool", args, {"json":"-p"}, JSON=JSON, fail=fail)
def bpftool_prog_list(expected=None):
_, progs = bpftool("prog show", JSON=True, fail=True)
if expected is not None:
if len(progs) != expected:
fail(True, "%d BPF programs loaded, expected %d" %
(len(progs), expected))
return progs
def bpftool_prog_list_wait(expected=0, n_retry=20):
for i in range(n_retry):
nprogs = len(bpftool_prog_list())
if nprogs == expected:
return
time.sleep(0.05)
raise Exception("Time out waiting for program counts to stabilize want %d, have %d" % (expected, nprogs))
def ip(args, force=False, JSON=True, fail=True):
if force:
args = "-force " + args
return tool("ip", args, {"json":"-j"}, JSON=JSON, fail=fail)
def tc(args, JSON=True, fail=True):
return tool("tc", args, {"json":"-p"}, JSON=JSON, fail=fail)
def ethtool(dev, opt, args, fail=True):
return cmd("ethtool %s %s %s" % (opt, dev["ifname"], args), fail=fail)
def bpf_obj(name, sec=".text", path=bpf_test_dir,):
return "obj %s sec %s" % (os.path.join(path, name), sec)
def bpf_pinned(name):
return "pinned %s" % (name)
def bpf_bytecode(bytecode):
return "bytecode \"%s\"" % (bytecode)
class DebugfsDir:
"""
Class for accessing DebugFS directories as a dictionary.
"""
def __init__(self, path):
self.path = path
self._dict = self._debugfs_dir_read(path)
def __len__(self):
return len(self._dict.keys())
def __getitem__(self, key):
if type(key) is int:
key = list(self._dict.keys())[key]
return self._dict[key]
def __setitem__(self, key, value):
log("DebugFS set %s = %s" % (key, value), "")
log_level_inc()
cmd("echo '%s' > %s/%s" % (value, self.path, key))
log_level_dec()
_, out = cmd('cat %s/%s' % (self.path, key))
self._dict[key] = out.strip()
def _debugfs_dir_read(self, path):
dfs = {}
log("DebugFS state for %s" % (path), "")
log_level_inc(add=2)
_, out = cmd('ls ' + path)
for f in out.split():
p = os.path.join(path, f)
if os.path.isfile(p):
_, out = cmd('cat %s/%s' % (path, f))
dfs[f] = out.strip()
elif os.path.isdir(p):
dfs[f] = DebugfsDir(p)
else:
raise Exception("%s is neither file nor directory" % (p))
log_level_dec()
log("DebugFS state", dfs)
log_level_dec()
return dfs
class NetdevSim:
"""
Class for netdevsim netdevice and its attributes.
"""
def __init__(self):
self.dev = self._netdevsim_create()
devs.append(self)
self.dfs_dir = '/sys/kernel/debug/netdevsim/%s' % (self.dev['ifname'])
self.dfs_refresh()
def __getitem__(self, key):
return self.dev[key]
def _netdevsim_create(self):
_, old = ip("link show")
ip("link add sim%d type netdevsim")
_, new = ip("link show")
for dev in new:
f = filter(lambda x: x["ifname"] == dev["ifname"], old)
if len(list(f)) == 0:
return dev
raise Exception("failed to create netdevsim device")
def remove(self):
devs.remove(self)
ip("link del dev %s" % (self.dev["ifname"]))
def dfs_refresh(self):
self.dfs = DebugfsDir(self.dfs_dir)
return self.dfs
def dfs_num_bound_progs(self):
path = os.path.join(self.dfs_dir, "bpf_bound_progs")
_, progs = cmd('ls %s' % (path))
return len(progs.split())
def dfs_get_bound_progs(self, expected):
progs = DebugfsDir(os.path.join(self.dfs_dir, "bpf_bound_progs"))
if expected is not None:
if len(progs) != expected:
fail(True, "%d BPF programs bound, expected %d" %
(len(progs), expected))
return progs
def wait_for_flush(self, bound=0, total=0, n_retry=20):
for i in range(n_retry):
nbound = self.dfs_num_bound_progs()
nprogs = len(bpftool_prog_list())
if nbound == bound and nprogs == total:
return
time.sleep(0.05)
raise Exception("Time out waiting for program counts to stabilize want %d/%d, have %d bound, %d loaded" % (bound, total, nbound, nprogs))
def set_mtu(self, mtu, fail=True):
return ip("link set dev %s mtu %d" % (self.dev["ifname"], mtu),
fail=fail)
def set_xdp(self, bpf, mode, force=False, fail=True):
return ip("link set dev %s xdp%s %s" % (self.dev["ifname"], mode, bpf),
force=force, fail=fail)
def unset_xdp(self, mode, force=False, fail=True):
return ip("link set dev %s xdp%s off" % (self.dev["ifname"], mode),
force=force, fail=fail)
def ip_link_show(self, xdp):
_, link = ip("link show dev %s" % (self['ifname']))
if len(link) > 1:
raise Exception("Multiple objects on ip link show")
if len(link) < 1:
return {}
fail(xdp != "xdp" in link,
"XDP program not reporting in iplink (reported %s, expected %s)" %
("xdp" in link, xdp))
return link[0]
def tc_add_ingress(self):
tc("qdisc add dev %s ingress" % (self['ifname']))
def tc_del_ingress(self):
tc("qdisc del dev %s ingress" % (self['ifname']))
def tc_flush_filters(self, bound=0, total=0):
self.tc_del_ingress()
self.tc_add_ingress()
self.wait_for_flush(bound=bound, total=total)
def tc_show_ingress(self, expected=None):
# No JSON support, oh well...
flags = ["skip_sw", "skip_hw", "in_hw"]
named = ["protocol", "pref", "chain", "handle", "id", "tag"]
args = "-s filter show dev %s ingress" % (self['ifname'])
_, out = tc(args, JSON=False)
filters = []
lines = out.split('\n')
for line in lines:
words = line.split()
if "handle" not in words:
continue
fltr = {}
for flag in flags:
fltr[flag] = flag in words
for name in named:
try:
idx = words.index(name)
fltr[name] = words[idx + 1]
except ValueError:
pass
filters.append(fltr)
if expected is not None:
fail(len(filters) != expected,
"%d ingress filters loaded, expected %d" %
(len(filters), expected))
return filters
def cls_bpf_add_filter(self, bpf, da=False, skip_sw=False, skip_hw=False,
fail=True):
params = ""
if da:
params += " da"
if skip_sw:
params += " skip_sw"
if skip_hw:
params += " skip_hw"
return tc("filter add dev %s ingress bpf %s %s" %
(self['ifname'], bpf, params), fail=fail)
def set_ethtool_tc_offloads(self, enable, fail=True):
args = "hw-tc-offload %s" % ("on" if enable else "off")
return ethtool(self, "-K", args, fail=fail)
################################################################################
def clean_up():
for dev in devs:
dev.remove()
for f in files:
cmd("rm -f %s" % (f))
def pin_prog(file_name, idx=0):
progs = bpftool_prog_list(expected=(idx + 1))
prog = progs[idx]
bpftool("prog pin id %d %s" % (prog["id"], file_name))
files.append(file_name)
return file_name, bpf_pinned(file_name)
# Parse command line
parser = argparse.ArgumentParser()
parser.add_argument("--log", help="output verbose log to given file")
args = parser.parse_args()
if args.log:
logfile = open(args.log, 'w+')
logfile.write("# -*-Org-*-")
log("Prepare...", "", level=1)
log_level_inc()
# Check permissions
skip(os.getuid() != 0, "test must be run as root")
# Check tools
ret, progs = bpftool("prog", fail=False)
skip(ret != 0, "bpftool not installed")
# Check no BPF programs are loaded
skip(len(progs) != 0, "BPF programs already loaded on the system")
# Check netdevsim
ret, out = cmd("modprobe netdevsim", fail=False)
skip(ret != 0, "netdevsim module could not be loaded")
# Check debugfs
_, out = cmd("mount")
if out.find("/sys/kernel/debug type debugfs") == -1:
cmd("mount -t debugfs none /sys/kernel/debug")
# Check samples are compiled
samples = ["sample_ret0.o"]
for s in samples:
ret, out = cmd("ls %s/%s" % (bpf_test_dir, s), fail=False)
skip(ret != 0, "sample %s/%s not found, please compile it" %
(bpf_test_dir, s))
try:
obj = bpf_obj("sample_ret0.o")
bytecode = bpf_bytecode("1,6 0 0 4294967295,")
start_test("Test destruction of generic XDP...")
sim = NetdevSim()
sim.set_xdp(obj, "generic")
sim.remove()
bpftool_prog_list_wait(expected=0)
sim = NetdevSim()
sim.tc_add_ingress()
start_test("Test TC non-offloaded...")
ret, _ = sim.cls_bpf_add_filter(obj, skip_hw=True, fail=False)
fail(ret != 0, "Software TC filter did not load")
start_test("Test TC non-offloaded isn't getting bound...")
ret, _ = sim.cls_bpf_add_filter(obj, fail=False)
fail(ret != 0, "Software TC filter did not load")
sim.dfs_get_bound_progs(expected=0)
sim.tc_flush_filters()
start_test("Test TC offloads are off by default...")
ret, _ = sim.cls_bpf_add_filter(obj, skip_sw=True, fail=False)
fail(ret == 0, "TC filter loaded without enabling TC offloads")
sim.wait_for_flush()
sim.set_ethtool_tc_offloads(True)
sim.dfs["bpf_tc_non_bound_accept"] = "Y"
start_test("Test TC offload by default...")
ret, _ = sim.cls_bpf_add_filter(obj, fail=False)
fail(ret != 0, "Software TC filter did not load")
sim.dfs_get_bound_progs(expected=0)
ingress = sim.tc_show_ingress(expected=1)
fltr = ingress[0]
fail(not fltr["in_hw"], "Filter not offloaded by default")
sim.tc_flush_filters()
start_test("Test TC cBPF bytcode tries offload by default...")
ret, _ = sim.cls_bpf_add_filter(bytecode, fail=False)
fail(ret != 0, "Software TC filter did not load")
sim.dfs_get_bound_progs(expected=0)
ingress = sim.tc_show_ingress(expected=1)
fltr = ingress[0]
fail(not fltr["in_hw"], "Bytecode not offloaded by default")
sim.tc_flush_filters()
sim.dfs["bpf_tc_non_bound_accept"] = "N"
start_test("Test TC cBPF unbound bytecode doesn't offload...")
ret, _ = sim.cls_bpf_add_filter(bytecode, skip_sw=True, fail=False)
fail(ret == 0, "TC bytecode loaded for offload")
sim.wait_for_flush()
start_test("Test TC offloads work...")
ret, _ = sim.cls_bpf_add_filter(obj, skip_sw=True, fail=False)
fail(ret != 0, "TC filter did not load with TC offloads enabled")
start_test("Test TC offload basics...")
dfs = sim.dfs_get_bound_progs(expected=1)
progs = bpftool_prog_list(expected=1)
ingress = sim.tc_show_ingress(expected=1)
dprog = dfs[0]
prog = progs[0]
fltr = ingress[0]
fail(fltr["skip_hw"], "TC does reports 'skip_hw' on offloaded filter")
fail(not fltr["in_hw"], "TC does not report 'in_hw' for offloaded filter")
fail(not fltr["skip_sw"], "TC does not report 'skip_sw' back")
start_test("Test TC offload is device-bound...")
fail(str(prog["id"]) != fltr["id"], "Program IDs don't match")
fail(prog["tag"] != fltr["tag"], "Program tags don't match")
fail(fltr["id"] != dprog["id"], "Program IDs don't match")
fail(dprog["state"] != "xlated", "Offloaded program state not translated")
fail(dprog["loaded"] != "Y", "Offloaded program is not loaded")
start_test("Test disabling TC offloads is rejected while filters installed...")
ret, _ = sim.set_ethtool_tc_offloads(False, fail=False)
fail(ret == 0, "Driver should refuse to disable TC offloads with filters installed...")
start_test("Test qdisc removal frees things...")
sim.tc_flush_filters()
sim.tc_show_ingress(expected=0)
start_test("Test disabling TC offloads is OK without filters...")
ret, _ = sim.set_ethtool_tc_offloads(False, fail=False)
fail(ret != 0,
"Driver refused to disable TC offloads without filters installed...")
sim.set_ethtool_tc_offloads(True)
start_test("Test destroying device gets rid of TC filters...")
sim.cls_bpf_add_filter(obj, skip_sw=True)
sim.remove()
bpftool_prog_list_wait(expected=0)
sim = NetdevSim()
sim.set_ethtool_tc_offloads(True)
start_test("Test destroying device gets rid of XDP...")
sim.set_xdp(obj, "offload")
sim.remove()
bpftool_prog_list_wait(expected=0)
sim = NetdevSim()
sim.set_ethtool_tc_offloads(True)
start_test("Test XDP prog reporting...")
sim.set_xdp(obj, "drv")
ipl = sim.ip_link_show(xdp=True)
progs = bpftool_prog_list(expected=1)
fail(ipl["xdp"]["prog"]["id"] != progs[0]["id"],
"Loaded program has wrong ID")
start_test("Test XDP prog replace without force...")
ret, _ = sim.set_xdp(obj, "drv", fail=False)
fail(ret == 0, "Replaced XDP program without -force")
sim.wait_for_flush(total=1)
start_test("Test XDP prog replace with force...")
ret, _ = sim.set_xdp(obj, "drv", force=True, fail=False)
fail(ret != 0, "Could not replace XDP program with -force")
bpftool_prog_list_wait(expected=1)
ipl = sim.ip_link_show(xdp=True)
progs = bpftool_prog_list(expected=1)
fail(ipl["xdp"]["prog"]["id"] != progs[0]["id"],
"Loaded program has wrong ID")
start_test("Test XDP prog replace with bad flags...")
ret, _ = sim.set_xdp(obj, "offload", force=True, fail=False)
fail(ret == 0, "Replaced XDP program with a program in different mode")
ret, _ = sim.set_xdp(obj, "", force=True, fail=False)
fail(ret == 0, "Replaced XDP program with a program in different mode")
start_test("Test XDP prog remove with bad flags...")
ret, _ = sim.unset_xdp("offload", force=True, fail=False)
fail(ret == 0, "Removed program with a bad mode mode")
ret, _ = sim.unset_xdp("", force=True, fail=False)
fail(ret == 0, "Removed program with a bad mode mode")
start_test("Test MTU restrictions...")
ret, _ = sim.set_mtu(9000, fail=False)
fail(ret == 0,
"Driver should refuse to increase MTU to 9000 with XDP loaded...")
sim.unset_xdp("drv")
bpftool_prog_list_wait(expected=0)
sim.set_mtu(9000)
ret, _ = sim.set_xdp(obj, "drv", fail=False)
fail(ret == 0, "Driver should refuse to load program with MTU of 9000...")
sim.set_mtu(1500)
sim.wait_for_flush()
start_test("Test XDP offload...")
sim.set_xdp(obj, "offload")
ipl = sim.ip_link_show(xdp=True)
link_xdp = ipl["xdp"]["prog"]
progs = bpftool_prog_list(expected=1)
prog = progs[0]
fail(link_xdp["id"] != prog["id"], "Loaded program has wrong ID")
start_test("Test XDP offload is device bound...")
dfs = sim.dfs_get_bound_progs(expected=1)
dprog = dfs[0]
fail(prog["id"] != link_xdp["id"], "Program IDs don't match")
fail(prog["tag"] != link_xdp["tag"], "Program tags don't match")
fail(str(link_xdp["id"]) != dprog["id"], "Program IDs don't match")
fail(dprog["state"] != "xlated", "Offloaded program state not translated")
fail(dprog["loaded"] != "Y", "Offloaded program is not loaded")
start_test("Test removing XDP program many times...")
sim.unset_xdp("offload")
sim.unset_xdp("offload")
sim.unset_xdp("drv")
sim.unset_xdp("drv")
sim.unset_xdp("")
sim.unset_xdp("")
bpftool_prog_list_wait(expected=0)
start_test("Test attempt to use a program for a wrong device...")
sim2 = NetdevSim()
sim2.set_xdp(obj, "offload")
pin_file, pinned = pin_prog("/sys/fs/bpf/tmp")
ret, _ = sim.set_xdp(pinned, "offload", fail=False)
fail(ret == 0, "Pinned program loaded for a different device accepted")
sim2.remove()
ret, _ = sim.set_xdp(pinned, "offload", fail=False)
fail(ret == 0, "Pinned program loaded for a removed device accepted")
rm(pin_file)
bpftool_prog_list_wait(expected=0)
start_test("Test mixing of TC and XDP...")
sim.tc_add_ingress()
sim.set_xdp(obj, "offload")
ret, _ = sim.cls_bpf_add_filter(obj, skip_sw=True, fail=False)
fail(ret == 0, "Loading TC when XDP active should fail")
sim.unset_xdp("offload")
sim.wait_for_flush()
sim.cls_bpf_add_filter(obj, skip_sw=True)
ret, _ = sim.set_xdp(obj, "offload", fail=False)
fail(ret == 0, "Loading XDP when TC active should fail")
start_test("Test binding TC from pinned...")
pin_file, pinned = pin_prog("/sys/fs/bpf/tmp")
sim.tc_flush_filters(bound=1, total=1)
sim.cls_bpf_add_filter(pinned, da=True, skip_sw=True)
sim.tc_flush_filters(bound=1, total=1)
start_test("Test binding XDP from pinned...")
sim.set_xdp(obj, "offload")
pin_file, pinned = pin_prog("/sys/fs/bpf/tmp2", idx=1)
sim.set_xdp(pinned, "offload", force=True)
sim.unset_xdp("offload")
sim.set_xdp(pinned, "offload", force=True)
sim.unset_xdp("offload")
start_test("Test offload of wrong type fails...")
ret, _ = sim.cls_bpf_add_filter(pinned, da=True, skip_sw=True, fail=False)
fail(ret == 0, "Managed to attach XDP program to TC")
start_test("Test asking for TC offload of two filters...")
sim.cls_bpf_add_filter(obj, da=True, skip_sw=True)
sim.cls_bpf_add_filter(obj, da=True, skip_sw=True)
# The above will trigger a splat until TC cls_bpf drivers are fixed
sim.tc_flush_filters(bound=2, total=2)
start_test("Test if netdev removal waits for translation...")
delay_msec = 500
sim.dfs["bpf_bind_verifier_delay"] = delay_msec
start = time.time()
cmd_line = "tc filter add dev %s ingress bpf %s da skip_sw" % \
(sim['ifname'], obj)
tc_proc = cmd(cmd_line, background=True, fail=False)
# Wait for the verifier to start
while sim.dfs_num_bound_progs() <= 2:
pass
sim.remove()
end = time.time()
ret, _ = cmd_result(tc_proc, fail=False)
time_diff = end - start
log("Time", "start:\t%s\nend:\t%s\ndiff:\t%s" % (start, end, time_diff))
fail(ret == 0, "Managed to load TC filter on a unregistering device")
delay_sec = delay_msec * 0.001
fail(time_diff < delay_sec, "Removal process took %s, expected %s" %
(time_diff, delay_sec))
print("%s: OK" % (os.path.basename(__file__)))
finally:
log("Clean up...", "", level=1)
log_level_inc()
clean_up()