Re: [PATCH net-next v8 2/3] selftests: tc-testing: add fq_pie per-flow class stats test

Thank you for the review. Our response to the low-severity comment is inline below.

[Severity: Low]
This is a robustness point, not a bug. fq_pie_walk() in
net/sched/sch_fq_pie.c only dumps flows that have a non-empty flowchain:

    if (list_empty(&q->flows[i].flowchain)) {
        arg->count++;
        continue;
    }

That makes this ping the only thing that gets class 2:1 into the output.

In the standard tdc setup this works. nsPlugin runs the command inside
the namespace, dummy is NOARP, and the 98-byte frame fits under tbf's
max_size of 100.

If ping is missing, or doesn't accept -i 0.001 / -W 0.01, the "|| true"
and the redirect hide the error. The test then fails as a regex mismatch
in the verify stage, not as a setup error.

Should this step be allowed to fail visibly? The same pattern is already
used elsewhere in tc-testing (infra/qdiscs.json), so it may be fine as is.

Keeping it as is. tc-tests/infra/qdiscs.json (test ca5e, "Check class
delete notification for ffff:") already uses the identical pattern:

    "ping -c1 -W0.01 -I $DUMMY 10.10.10.1 || true",

as a setup step whose only job is to push a packet through the qdisc,
with the same silent-failure trade-off described above. 83c0 follows
existing practice here rather than introducing a new one.


Regards,
Hemendra