From: Song Liu <songliubraving@fb.com>
To: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Cc: bpf <bpf@vger.kernel.org>, "Alexei Starovoitov" <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Andrii Nakryiko" <andrii@kernel.org>,
"Martin Lau" <kafai@fb.com>, "Yonghong Song" <yhs@fb.com>,
"Jesper Dangaard Brouer" <brouer@redhat.com>,
"Toke Høiland-Jørgensen" <toke@redhat.com>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>
Subject: Re: [PATCH bpf-next v5 11/12] bpf: selftests: Fix fd cleanup in get_branch_snapshot
Date: Tue, 28 Sep 2021 23:58:10 +0000 [thread overview]
Message-ID: <ECE882BB-B86B-41CB-AF2A-336DA95A5A4D@fb.com> (raw)
In-Reply-To: <20210927145941.1383001-12-memxor@gmail.com>
> On Sep 27, 2021, at 7:59 AM, Kumar Kartikeya Dwivedi <memxor@gmail.com> wrote:
>
> 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.
>
> Cc: Song Liu <songliubraving@fb.com>
> Fixes: 025bd7c753aa (selftests/bpf: Add test for bpf_get_branch_snapshot)
> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Thanks for the fix!
Acked-by: Song Liu <songliubraving@fb.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 f81db9135ae4..67e86f8d8677 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;
> --
> 2.33.0
>
next prev parent reply other threads:[~2021-09-28 23:58 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-27 14:59 [PATCH bpf-next v5 00/12] Support kernel module function calls from eBPF Kumar Kartikeya Dwivedi
2021-09-27 14:59 ` [PATCH bpf-next v5 01/12] bpf: Introduce BPF support for kernel module function calls Kumar Kartikeya Dwivedi
2021-09-27 14:59 ` [PATCH bpf-next v5 02/12] bpf: Be conservative while processing invalid kfunc calls Kumar Kartikeya Dwivedi
2021-09-27 14:59 ` [PATCH bpf-next v5 03/12] bpf: btf: Introduce helpers for dynamic BTF set registration Kumar Kartikeya Dwivedi
2021-09-27 14:59 ` [PATCH bpf-next v5 04/12] tools: Allow specifying base BTF file in resolve_btfids Kumar Kartikeya Dwivedi
2021-09-27 14:59 ` [PATCH bpf-next v5 05/12] bpf: Enable TCP congestion control kfunc from modules Kumar Kartikeya Dwivedi
2021-09-27 14:59 ` [PATCH bpf-next v5 06/12] libbpf: Support kernel module function calls Kumar Kartikeya Dwivedi
2021-09-27 14:59 ` [PATCH bpf-next v5 07/12] libbpf: Resolve invalid weak kfunc calls with imm = 0, off = 0 Kumar Kartikeya Dwivedi
2021-09-27 14:59 ` [PATCH bpf-next v5 08/12] libbpf: Make gen_loader data aligned Kumar Kartikeya Dwivedi
2021-09-29 20:50 ` Alexei Starovoitov
2021-09-27 14:59 ` [PATCH bpf-next v5 09/12] libbpf: Update gen_loader to emit BTF_KIND_FUNC relocations Kumar Kartikeya Dwivedi
2021-09-29 0:01 ` Alexei Starovoitov
2021-09-29 0:10 ` Kumar Kartikeya Dwivedi
2021-09-27 14:59 ` [PATCH bpf-next v5 10/12] libbpf: Fix skel_internal.h to set errno on loader retval < 0 Kumar Kartikeya Dwivedi
2021-09-30 3:45 ` Alexei Starovoitov
2021-09-27 14:59 ` [PATCH bpf-next v5 11/12] bpf: selftests: Fix fd cleanup in get_branch_snapshot Kumar Kartikeya Dwivedi
2021-09-28 23:58 ` Song Liu [this message]
2021-09-29 20:26 ` Alexei Starovoitov
2021-09-27 14:59 ` [PATCH bpf-next v5 12/12] bpf: selftests: Add selftests for module kfunc support Kumar Kartikeya Dwivedi
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