linux/tools/include
Andrey Ignatov f5bfcd953d 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
2020-01-09 09:40:06 -08:00
..
asm tools: Add missing stdio.h include to asm/bug.h header 2019-09-25 09:51:44 -03:00
asm-generic treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 36 2019-05-24 17:27:11 +02:00
linux augmented rbtree: rework the RB_DECLARE_CALLBACKS macro definition 2019-09-25 17:51:39 -07:00
nolibc tool headers nolibc: add RISCV support 2019-05-08 15:48:43 +02:00
tools tools: bpf: fix license for a compat header file 2018-09-19 23:49:58 +02:00
trace/events tools/lib/lockdep: Remove private kernel headers 2017-06-05 09:28:14 +02:00
uapi bpf: Document BPF_F_QUERY_EFFECTIVE flag 2020-01-09 09:40:06 -08:00