fix(ebpf): synchronize perfUsageCollector.Collect with Manager.Start - #54952
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perfUsageCollector.Collect reads PerfMap/RingBuffer telemetry fields (e.g. BufferSize) during Prometheus Gather ticks, while ebpf.Manager.Start writes those same fields during eBPF program startup. The collector's mutex protected its own data structures but not the shared PerfMap/ RingBuffer objects. Change the collector mutex from sync.Mutex to sync.RWMutex so Collect takes RLock (reader), and export LockForWrite/UnlockForWrite so Manager.Start can take the write lock around m.Manager.Start(). This prevents Collect from reading telemetry fields while Start is writing them. Found via a race-detector-enabled build in staging (see #54333).
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What does this PR do?
Fixes a data race on
PerfMap/RingBuffertelemetry fields:perfUsageCollector.CollectreadsBufferSize()(which readsbufferSizewithout a lock) during Prometheus Gather ticks, whileebpf.Manager.Startwrites those same fields during eBPF program startup. Changes the collector mutex fromsync.Mutextosync.RWMutexsoCollecttakesRLock(reader), and exportsLockForWrite/UnlockForWritesoManager.Startcan take the write lock aroundm.Manager.Start().Motivation
Fix a race, found via a race-detector-enabled build in staging (see #54333 for context).
Describe how you validated your changes
Added
TestLockForWriteBlocksCollectandTestCollectConcurrentReaderswhich validate the lock mechanism:LockForWriteblocksCollectuntilUnlockForWriteis called, and multipleCollectcalls can run concurrently underRLock. Tests pass under-race(dda inv test --targets=./pkg/ebpf/telemetry/... --race). The actual race requires eBPF support to trigger (Manager.Start writes to PerfMap/RingBuffer internal fields), so the test validates the synchronization mechanism rather than the full race.