> On Jan 7, 2020, at 5:40 PM, Andrey Ignatov <rdna@xxxxxx> wrote:
>
> 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@xxxxxx>
Acked-by: Song Liu <songliubraving@xxxxxx>
With some nit below.
> ---
> include/uapi/linux/bpf.h | 7 ++++++-
> tools/include/uapi/linux/bpf.h | 7 ++++++-
> 2 files changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 7df436da542d..dc4b8a2d2a86 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -357,7 +357,12 @@ enum bpf_attach_type {
> /* Enable memory-mapping BPF map */
> #define BPF_F_MMAPABLE (1U << 10)
>
> -/* flags for BPF_PROG_QUERY */
> +/* Flags for BPF_PROG_QUERY. */
> +
> +/* Query effective (directly attached + inherited from ancestor cgroups)
> + * programs that will be executed for events within a cgroup.
> + * attach_flags with this flag are returned only for directly attached programs.
This line is more than 75 byte long, I guess ./scripts/checkpatch.pl would
complain about it?
Thanks,
Song
