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Bump contrib/libdeflate: fix data race in the CPU-feature global

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The previous bump (cb6b5c9) made the per-codec dispatch function pointers
(`crc32_impl`, `adler32_impl`, ...) atomic, but each dispatcher still calls
`get_x86_cpu_features` / `get_arm_cpu_features`, which lazily initialize the
global `libdeflate_x86_cpu_features` / `libdeflate_arm_cpu_features` bitmask on
the first call. That global was only `volatile`, so a plain load racing with
the store in `libdeflate_init_*_cpu_features` is still undefined behavior and
was flagged by ThreadSanitizer:

    WARNING: ThreadSanitizer: data race
      Write ... libdeflate_init_x86_cpu_features cpu_features.c:210
      Read  ... get_x86_cpu_features cpu_features.h:62
      Location is global 'libdeflate_x86_cpu_features'

It reproduced as a "Server died" failure under TSan when two HTTP connections
first compressed a gzip error response concurrently (e.g.
`test_profile_max_sessions_for_user` on the amd_tsan integration shard).

The global is now accessed with relaxed `__atomic_load_n` / `__atomic_store_n`,
matching the dispatch-pointer fix. Fork commit:
https://github.com/ClickHouse/libdeflate/commit/ec0718b
Related: https://github.com/ClickHouse/libdeflate/pull/5

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>
This commit is contained in:
Alexey Milovidov
2026-06-30 15:02:07 +00:00
co-authored by Claude Opus 4.8
parent 7626119d5f
commit d1038006e9
1 changed files with 1 additions and 1 deletions
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