[CWS] ebpfless: do not fallback on negative fds

[paulcacheux]

What does this PR do?

In some cases we end up trying to resolve the path from a negative fd (which is an error). This PR makes sure we shortcut early and directly return an error if this is the case.

Motivation

Additional Notes

Possible Drawbacks / Trade-offs

Describe how to test/QA your changes

[agent-platform-auto-pr]

[Fast Unit Tests Report]

On pipeline 40662677 (CI Visibility). The following jobs did not run any unit tests:

Jobs:

• tests_deb-arm64-py3
• tests_deb-x64-py3
• tests_flavor_dogstatsd_deb-x64
• tests_flavor_heroku_deb-x64
• tests_flavor_iot_deb-x64
• tests_rpm-arm64-py3
• tests_rpm-x64-py3
• tests_windows-x64

If you modified Go files and expected unit tests to run in these jobs, please double check the job logs. If you think tests should have been executed reach out to #agent-devx-help

[pr-commenter]

Test changes on VM

Use this command from test-infra-definitions to manually test this PR changes on a VM:

inv create-vm --pipeline-id=40662677 --os-family=ubuntu

Note: This applies to commit 0915ff2

[pr-commenter]

Regression Detector

Regression Detector Results

Run ID: dc23cf47-c2ec-4933-bd22-9e9ead059c2d Metrics dashboard Target profiles

Baseline: a6fe1f2
Comparison: 0915ff2

Performance changes are noted in the perf column of each table:

• ✅ = significantly better comparison variant performance
• ❌ = significantly worse comparison variant performance
• ➖ = no significant change in performance

No significant changes in experiment optimization goals

Confidence level: 90.00%
Effect size tolerance: |Δ mean %| ≥ 5.00%

There were no significant changes in experiment optimization goals at this confidence level and effect size tolerance.

Fine details of change detection per experiment

perf	experiment	goal	Δ mean %	Δ mean % CI	links
➖	tcp_syslog_to_blackhole	ingress throughput	+3.74	[-9.24, +16.73]	Logs
➖	uds_dogstatsd_to_api_cpu	% cpu utilization	+1.09	[+0.19, +1.98]	Logs
➖	basic_py_check	% cpu utilization	+0.91	[-1.71, +3.52]	Logs
➖	idle	memory utilization	+0.57	[+0.53, +0.61]	Logs
➖	file_tree	memory utilization	+0.03	[-0.04, +0.09]	Logs
➖	uds_dogstatsd_to_api	ingress throughput	+0.00	[-0.00, +0.00]	Logs
➖	tcp_dd_logs_filter_exclude	ingress throughput	-0.00	[-0.01, +0.01]	Logs
➖	otel_to_otel_logs	ingress throughput	-0.43	[-1.23, +0.38]	Logs
➖	pycheck_1000_100byte_tags	% cpu utilization	-2.74	[-7.10, +1.62]	Logs

Explanation

A regression test is an A/B test of target performance in a repeatable rig, where "performance" is measured as "comparison variant minus baseline variant" for an optimization goal (e.g., ingress throughput). Due to intrinsic variability in measuring that goal, we can only estimate its mean value for each experiment; we report uncertainty in that value as a 90.00% confidence interval denoted "Δ mean % CI".

For each experiment, we decide whether a change in performance is a "regression" -- a change worth investigating further -- if all of the following criteria are true:

1. Its estimated |Δ mean %| ≥ 5.00%, indicating the change is big enough to merit a closer look.

2. Its 90.00% confidence interval "Δ mean % CI" does not contain zero, indicating that if our statistical model is accurate, there is at least a 90.00% chance there is a difference in performance between baseline and comparison variants.

3. Its configuration does not mark it "erratic".

[paulcacheux]

/merge

[dd-devflow]

🚂 MergeQueue: pull request added to the queue

The median merge time in main is 23m.

Use /merge -c to cancel this operation!