Commit 4b82b181a26c ("bpf: Allow pre-ordering for bpf cgroup progs")
introduced BPF_F_PREORDER to request pre-order execution across the
cgroup hierarchy. While the kernel records BPF_F_PREORDER in pl->flags,
__cgroup_bpf_query() currently fails to report it to user space in
prog_attach_flags[] during direct cgroup program queries.This series fixes the kernel query path, extends BPF selftests to verify the fix, and updates bpftool to recognize and format the BPF_F_PREORDER flag. Patch 1 fixes __cgroup_bpf_query() to merge (pl->flags & BPF_F_PREORDER) with cgroup flags when copying per-program attach flags to user space. Patch 2 extends selftests/bpf (cgroup_mprog_opts) to verify that direct and link queries report BPF_F_PREORDER (0x42), matching programs by prog_id with guarded failure paths. Patch 3 adds bpftool support: a bitmask flags formatter for cgroup show, support for "preorder" in cgroup attach, documentation updates, and bash completion. Testing: - Verified on unpatched kernel: selftest reproduces failure (actual 2 != expected 66). - Verified on patched kernel (bpf/master): both cgroup_mprog_opts and cgroup_preorder pass 100% in QEMU guest environment. - Verified bpftool build, format unit tests, and checkpatch (0 errors, 0 warnings). Hui Su (3): bpf: Report BPF_F_PREORDER in cgroup program queries selftests/bpf: Test querying BPF_F_PREORDER cgroup attachments bpftool: Add support for BPF_F_PREORDER cgroup attach flag kernel/bpf/cgroup.c | 16 ++-- .../bpftool/Documentation/bpftool-cgroup.rst | 9 +- tools/bpf/bpftool/bash-completion/bpftool | 2 +- tools/bpf/bpftool/cgroup.c | 55 +++++++---- .../bpf/prog_tests/cgroup_mprog_opts.c | 94 ++++++++++++++++++- 5 files changed, 144 insertions(+), 32 deletions(-) -- 2.55.0
