Re: [PATCH bpf-next v2] selftests/bpf: Track test_xdp_features DUT processes

[Alexis Lothoré]

Hi Daniel, thanks for the notification

On Mon Aug 24, 2026 at 1:31 PM CEST, Daniel Borkmann wrote:
> [ Trimming the excessive Cc list, and adding Alexis ]
>
> On 8/12/26 10:28 AM, Bochao Cao via B4 Relay wrote:
>> From: Bochao Cao <bochaolucky@xxxxxxxxx>
>> 
>> test_xdp_features.sh waits for any xdp_features listener to appear and
>> uses pidof during cleanup. A concurrent test can therefore make another
>> test proceed before its own DUT is ready, and cleanup kills every
>> xdp_features process on the host. The readiness loop also has no timeout,
>> so a DUT that exits before listening leaves the test hung indefinitely.
>> 
>> Track one active DUT at a time, wait for ss to report that exact PID with
>> a bounded retry loop, and reap it after each test. Consult the shell job
>> table before signaling the DUT so a stale PID cannot target an unrelated
>> process. On failure, terminate the shell job with SIGKILL and reap it so
>> blocked I/O cannot hang cleanup. Install an EXIT trap and signal handlers
>> so failure paths also remove network setup.
>> 
>> Fixes: 4dba3e7852b7 ("selftests/bpf: introduce XDP compliance test tool")
>> Closes: https://bugs.debian.org/1136522
>> Signed-off-by: Bochao Cao <bochaolucky@xxxxxxxxx>
>> ---
>> Tests:
>> - bash -n tools/testing/selftests/bpf/test_xdp_features.sh
>> - make -C tools/testing/selftests/bpf xdp_features
>> - sudo tools/testing/selftests/bpf/test_xdp_features.sh
>> - verified cleanup terminates a blocked DUT without affecting an unrelated process
>> ---
>> Changes in v2:
>> - Clarify that avoiding name-wide process matching, rather than dropping a dependency, is the motivation.
>> - Track and reap one active DUT at a time instead of retaining historical PIDs.
>> - Address PID reuse by signaling only the current Bash job during cleanup.
>> - Use SIGKILL on failure cleanup so blocked DUT I/O cannot hang wait indefinitely.
>> - Link to v1: https://patch.msgid.link/20260805-xdp-dut-process-lifecycle-gmail-v1-1-45984df8d295@xxxxxxxxx
>> ---
>>   tools/testing/selftests/bpf/test_xdp_features.sh | 82 ++++++++++++++++++------
>>   1 file changed, 62 insertions(+), 20 deletions(-)
>
> Sorry for the late reply. With regards to https://bugs.debian.org/1136522, src:linux deb
> does not have to depend on this at all, so the src:linux can just get rid of procps in
> any case if this is indeed the last dependency. I'm not seeing the test being run in our
> BPF CI. I've Cc'ed Alexis as he's in the process of migrating and/or removing tests from
> tools/testing/selftests/bpf/ depending on how they fit into test_progs framework. I'll
> let him comment if there is already work in progress. It feels like this script could be
> reworked into tools/testing/selftests/drivers/net/hw/ tests and removed altogether from
> the tools/testing/selftests/bpf/ dir.

There has been an attempt to fully convert and get rid of
test_xdp_features.sh, but discussions around the corresponding series
highlighted the need for the script to remain available for testing on
real hardware.  Features covered by the test_xdp_features.sh that were
not covered yet by test_progs have been added to test_progs (in
xdp_cpumap_attach), see [1]. So there's currently no active effort on
this one on my side.

Alexis

[1] https://lore.kernel.org/bpf/20241009-convert_xdp_tests-v3-0-51cea913710c@xxxxxxxxxxx/

-- 
Alexis Lothoré, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com