+ Stan
On Wed, Jun 25, 2025 at 04:39:45AM -0700, Breno Leitao wrote:
I am submitting a new selftest for the netpoll subsystem specifically targeting the case where the RX is polling in the TX path, which is a case that we don't have any test in the tree today. This is done when netpoll_poll_dev() called, and this test creates a scenario when that is probably.
The test does the following:
- Configuring a single RX/TX queue to increase contention on the interface.
- Generating background traffic to saturate the network, mimicking real-world congestion.
- Sending netconsole messages to trigger netpoll polling and monitor its behavior.
- Using dynamic netconsole targets via configfs, with the ability to delete and recreate targets during the test.
- Running bpftrace in parallel to verify that netpoll_poll_dev() is called when expected. If it is called, then the test passes, otherwise the test is marked as skipped.
In order to achieve it, I stole Jakub's bpftrace helper from [1], and did some small changes that I found useful to use the helper.
So, this patchset basically contains:
- The code stolen from Jakub
- Improvements on bpftrace() helper
- The selftest itself
Link: https://lore.kernel.org/all/20250421222827.283737-22-kuba@kernel.org/ [1]
Jakub, Stan, all,
It looks like bpftrace needs to be installed on the CI workers. Currently they report something a lot like this:
# timeout set to 180 # selftests: drivers/net: netpoll_basic.py # Exception in thread Thread-1: # Traceback (most recent call last): # File "/usr/lib64/python3.9/threading.py", line 980, in _bootstrap_inner # self.run() # File "/usr/lib64/python3.9/threading.py", line 917, in run # self._target(*self._args, **self._kwargs) # File "/home/virtme/testing-17/tools/testing/selftests/drivers/net/./netpoll_basic.py", line 198, in bpftrace_call # MAPS = bpftrace(expr, timeout=BPFTRACE_TIMEOUT, json=True) # File "/home/virtme/testing-17/tools/testing/selftests/net/lib/py/utils.py", line 205, in bpftrace # cmd_obj = cmd(cmd_arr, ns=ns, host=host, shell=False) # File "/home/virtme/testing-17/tools/testing/selftests/net/lib/py/utils.py", line 60, in __init__ # self.proc = subprocess.Popen(comm, shell=shell, stdout=subprocess.PIPE, # File "/usr/lib64/python3.9/subprocess.py", line 951, in __init__ # self._execute_child(args, executable, preexec_fn, close_fds, # File "/usr/lib64/python3.9/subprocess.py", line 1837, in _execute_child # raise child_exception_type(errno_num, err_msg, err_filename) # FileNotFoundError: [Errno 2] No such file or directory: 'bpftrace' # TAP version 13 # 1..1 # # Exception| Traceback (most recent call last): # # Exception| File "/home/virtme/testing-17/tools/testing/selftests/net/lib/py/ksft.py", line 243, in ksft_run # # Exception| case(*args) # # Exception| File "/home/virtme/testing-17/tools/testing/selftests/drivers/net/./netpoll_basic.py", line 308, in test_netpoll # # Exception| do_netpoll_flush_monitored(cfg, netdevnl, ifname, target_name) # # Exception| File "/home/virtme/testing-17/tools/testing/selftests/drivers/net/./netpoll_basic.py", line 243, in do_netpoll_flush_monitored # # Exception| do_netpoll_flush(cfg, netdevnl, ifname, target_name) # # Exception| File "/home/virtme/testing-17/tools/testing/selftests/drivers/net/./netpoll_basic.py", line 278, in do_netpoll_flush # # Exception| if bpftrace_any_hit(join=False): # # Exception| File "/home/virtme/testing-17/tools/testing/selftests/drivers/net/./netpoll_basic.py", line 230, in bpftrace_any_hit # # Exception| raise KsftFailEx(f"bpftrace failed to run!?: {MAPS}") # # Exception| net.lib.py.ksft.KsftFailEx: bpftrace failed to run!?: {} # not ok 1 netpoll_basic.test_netpoll # # Totals: pass:0 fail:1 xfail:0 xpass:0 skip:0 error:0