fix(bpf) Initialize cilium_percpu_trace_id map via Hive Start hook#41886
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julianwiedmann merged 1 commit intocilium:mainfrom Oct 21, 2025
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fix(bpf) Initialize cilium_percpu_trace_id map via Hive Start hook#41886julianwiedmann merged 1 commit intocilium:mainfrom
julianwiedmann merged 1 commit intocilium:mainfrom
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This commit resolves a rare concurrency flake observed in CI during agent startup when loading BPF collections. The `cilium_percpu_trace_id` map is defined with `LIBBPF_PIN_BY_NAME`, which means it must be initialized and pinned to the BPF filesystem only once. Previously, this map was created as part of the generic BPF collection loading mechanism, which could execute concurrently across multiple components during agent initialization. This led to a race condition. - The first thread successfully creates and **pins** the map (`/sys/fs/bpf/...`). - Subsequent concurrent threads fail when trying to **re-pin** the map, resulting in the `file exists` error and agent failure. This fix: - moves the map initialization to a Hive start hook - adds testing for the new initialization Signed-off-by: Ben Bigdelle <[email protected]>
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Description
This PR resolves a race condition during agent startup that caused CI flakes when loading the cilium_percpu_trace_id BPF map.
As noted by this #41306 (comment), the original error seen in logs was:
error="loading eBPF collection into the kernel: map cilium_percpu_trace_id: pin map to /sys/fs/bpf/tc/globals/cilium_percpu_trace_id: file exists"Cause
The cilium_percpu_trace_id map is defined with the LIBBPF_PIN_BY_NAME flag, making it a globally shared, pinned map, so because multiple datapath components start and load BPF programs concurrently during agent initialization, multiple goroutines were attempting to create/pin this BPF map simultaneously. The first attempt works, but all other attempts fail with the message linked above.
Fix
The map's initializeion is now done via Hive injection: A dedicated iptrace.Cell is registered in daemon/cmd/cells.go. This uses the OnStart hook to call
OpenOrCreate()for the cilium_percpu_trace_id map.Fixes: #42125