path: root/tools/lib/bpf/libbpf.c
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authorAndrey Ignatov <rdna@fb.com>2020-01-07 17:40:06 -0800
committerAlexei Starovoitov <ast@kernel.org>2020-01-09 09:40:06 -0800
commitf5bfcd953d811dbb8913de36b96b38da6bb62135 (patch)
treead65489a49e1c9a2b54411bff64256c5d6a30159 /tools/lib/bpf/libbpf.c
parentMerge branch 'tcp-bpf-cc' (diff)
bpf: Document BPF_F_QUERY_EFFECTIVE flag
Document BPF_F_QUERY_EFFECTIVE flag, mostly to clarify how it affects attach_flags what may not be obvious and what may lead to confision. Specifically attach_flags is returned only for target_fd but if programs are inherited from an ancestor cgroup then returned attach_flags for current cgroup may be confusing. For example, two effective programs of same attach_type can be returned but w/o BPF_F_ALLOW_MULTI in attach_flags. Simple repro: # bpftool c s /sys/fs/cgroup/path/to/task ID AttachType AttachFlags Name # bpftool c s /sys/fs/cgroup/path/to/task effective ID AttachType AttachFlags Name 95043 ingress tw_ipt_ingress 95048 ingress tw_ingress Signed-off-by: Andrey Ignatov <rdna@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20200108014006.938363-1-rdna@fb.com
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