selftests/bpf: Add torn write detection test for htab BPF_F_LOCK

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Add a consistency subtest to htab_reuse that detects torn writes
caused by the BPF_F_LOCK lockless update racing with element
reallocation in alloc_htab_elem().

The test uses three thread roles started simultaneously via a pipe:
 - locked updaters: BPF_F_LOCK|BPF_EXIST in-place updates
 - delete+update workers: delete then BPF_ANY|BPF_F_LOCK insert
 - locked readers: BPF_F_LOCK lookup checking value consistency

Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Link: https://lore.kernel.org/r/20260401-bpf_map_torn_writes-v1-2-782d071c55e7@meta.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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Mykyta Yatsenko 2026-04-01 06:50:37 -07:00 • committed by Alexei Starovoitov

parent 07738bc566

commit f64eb44ce9

2 changed files with 184 additions and 1 deletions

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169

tools/testing/selftests/bpf/prog_tests/htab_reuse.c

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16

tools/testing/selftests/bpf/progs/htab_reuse.c

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