hwmon: disambiguate colliding chip labels#3646
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Multiple hwmon nodes can be registered under a single parent device (for example asus-nb-wmi exposes one hwmon for fan control and another for WMI sensors). Both currently resolve to the same chip label (`platform_asus_nb_wmi`) and trigger "metric collected before with the same name and label values" errors at scrape time. Detect this collision in a first pass and append the chip's `name` file content (or the hwmonX basename if names also collide) to the chip label in a second pass. The include/exclude filter is moved into the same pass so user regexes match the label that is actually emitted. Fixes: prometheus#3637 Signed-off-by: Matthew Wimpelberg <matt.wimpelberg@grafana.com>
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@SuperQ would you have a moment to take a look? Happy to address any feedback. |
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This should add to the test fixtures so that it's tested in the end-to-end test. |
SuperQ
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May 15, 2026
Co-authored-by: Ben Kochie <superq@gmail.com> Signed-off-by: Matthew Wimpelberg <120263653+mwimpelberg28@users.noreply.github.com>
Two new hwmon nodes share a single platform device (asus-nb-wmi) with distinct `name` file contents, exercising the disambiguation path in the end-to-end test. Without the fix in the previous commit, the duplicate base chip name `platform_asus_nb_wmi` would have triggered a registry error before any metrics were scraped. Also expand the e2e chip-include regex to admit the new chips so their disambiguated labels appear in the expected output. Signed-off-by: Matthew Wimpelberg <matt.wimpelberg@grafana.com>
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This should be fixed. |
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Summary
Fixes #3637.
Multiple hwmon nodes can be registered under a single parent device — for example,
asus-nb-wmion recent ASUS laptops registers one hwmon for fan control and another for WMI sensors. Bothdevicesymlinks resolve to the same/sys/devices/platform/asus-nb-wmi, sohwmonNameproduces the sameplatform_asus_nb_wmichip label for both, and any sensor file that exists in both nodes (e.g.pwm1_enable) trips:Approach
Updatenow does two passes:/sys/class/hwmon/*, compute the device-derived base chip name for each, and count collisions.namefile content if it disambiguates, otherwise with the hwmonX basename (always unique within a boot). The include/exclude filter is also moved here so user regexes match the label that is actually emitted in the metric.Entries that already produce a unique chip label are unaffected — no surprise suffixes for users not hitting the collision.
This is closer in spirit to the discussion in #333 (the same class of bug for dual-socket
coretempboxes), but contained: the fix only kicks in when an actual collision is detected.Test plan
New
collector/hwmon_linux_test.go:TestHwmonDuplicateChipNamesAreDisambiguated— reproduces the Metric node_hwmon_pwm_enable was collected before with the same name and label values #3637 ASUS WMI scenario (two hwmon dirs sharing one platform device, both exposingpwm1_enable) and asserts bothGathersucceeds and the chip labels are distinct.TestHwmonUniqueChipNamesAreUnchanged— guards against unintended label drift for users not hitting the collision.TestHwmonDuplicateChipNamesWithSameNameFile— exercises the hwmonX-basename fallback when thenamefile content also collides.go test ./collector/), including the existing fixture-driven e2e checks.go vet ./...clean.