From e31eec77e4ab90dcec7d2da93415f839098dc287 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Mon, 27 Sep 2021 20:29:40 +0530 Subject: [PATCH] bpf: selftests: Fix fd cleanup in get_branch_snapshot Cleanup code uses while (cpu++ < cpu_cnt) for closing fds, which means it starts iterating from 1 for closing fds. If the first fd is -1, it skips over it and closes garbage fds (typically zero) in the remaining array. This leads to test failures for future tests when they end up storing fd 0 (as the slot becomes free due to close(0)) in ldimm64's BTF fd, ending up trying to match module BTF id with vmlinux. This was observed as spurious CI failure for the ksym_module_libbpf and module_attach tests. The test ends up closing fd 0 and breaking libbpf's assumption that module BTF fd will always be > 0, which leads to the kernel thinking that we are pointing to a BTF ID in vmlinux BTF. Fixes: 025bd7c753aa (selftests/bpf: Add test for bpf_get_branch_snapshot) Signed-off-by: Kumar Kartikeya Dwivedi Signed-off-by: Alexei Starovoitov Acked-by: Song Liu Link: https://lore.kernel.org/bpf/20210927145941.1383001-12-memxor@gmail.com --- tools/testing/selftests/bpf/prog_tests/get_branch_snapshot.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/tools/testing/selftests/bpf/prog_tests/get_branch_snapshot.c b/tools/testing/selftests/bpf/prog_tests/get_branch_snapshot.c index f81db91..67e86f8 100644 --- a/tools/testing/selftests/bpf/prog_tests/get_branch_snapshot.c +++ b/tools/testing/selftests/bpf/prog_tests/get_branch_snapshot.c @@ -38,10 +38,9 @@ static int create_perf_events(void) static void close_perf_events(void) { - int cpu = 0; - int fd; + int cpu, fd; - while (cpu++ < cpu_cnt) { + for (cpu = 0; cpu < cpu_cnt; cpu++) { fd = pfd_array[cpu]; if (fd < 0) break; -- 2.7.4