Fix eBPF FD PID map iteration - #22436
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Pull request overview
Fixes the eBPF FD collector’s per-PID map iteration so that the loop uses the PID returned by bpf_map_get_next_key() before attempting a bpf_map_lookup_elem(). This removes the per-cycle “Failed to lookup PID 0 in FD map” error and ensures the iteration processes the actual map entries (including the last key).
Changes:
- Update ebpf_read_fd_apps_table() to assign key = next_key immediately after bpf_map_get_next_key().
- Remove the stale end-of-loop key = next_key assignment that previously caused lookups against the wrong PID (notably 0 on the first iteration).
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thiagoftsm
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No issues found during runtime. LGTM!
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fix ebpf fd pid map iteration (cherry picked from commit de9a825)
Summary
Fix the eBPF FD collector's per-PID map iteration so it consumes the key returned by bpf_map_get_next_key() before looking up the map entry.
The previous loop seeded key with 0, received the first real PID in next_key, but still attempted to look up PID 0. When PID 0 was not present in the FD map, ebpf.plugin
logged:
once per collection cycle.
Root Cause
ebpf_read_fd_apps_table() used the stale input key after a successful bpf_map_get_next_key() call instead of the returned next_key.
Changes
Summary by cubic
Fix per-PID map iteration in the eBPF FD collector by assigning key = next_key before bpf_map_lookup_elem() lookups. This eliminates incorrect PID 0 lookups and the repeated "Failed to lookup PID 0 in FD map" log.
Written for commit ee2ad7d. Summary will update on new commits.