From: Pu Lehui <pulehui@xxxxxxxxxx> When root-cgroup attach multi progs and sub-cgroup attach a override prog, bpftool will display incorrectly for the attach flags of the sub-cgroup’s effective progs: $ bpftool cgroup tree /sys/fs/cgroup effective CgroupPath ID AttachType AttachFlags Name /sys/fs/cgroup 6 cgroup_sysctl multi sysctl_tcp_mem 13 cgroup_sysctl multi sysctl_tcp_mem /sys/fs/cgroup/cg1 20 cgroup_sysctl override sysctl_tcp_mem 6 cgroup_sysctl override sysctl_tcp_mem <- wrong 13 cgroup_sysctl override sysctl_tcp_mem <- wrong /sys/fs/cgroup/cg1/cg2 20 cgroup_sysctl sysctl_tcp_mem 6 cgroup_sysctl sysctl_tcp_mem 13 cgroup_sysctl sysctl_tcp_mem For cg1, obviously, the attach flags of prog6 and prog13 can not be OVERRIDE. And for query with EFFECTIVE flags, exporting attach flags does not make sense, we can remove this logic. After these patches, the above situation will show as bellow: # bpftool cgroup tree /sys/fs/cgroup effective CgroupPath ID AttachType Name /sys/fs/cgroup 6 cgroup_sysctl sysctl_tcp_mem 13 cgroup_sysctl sysctl_tcp_mem /sys/fs/cgroup/cg1 20 cgroup_sysctl sysctl_tcp_mem 6 cgroup_sysctl sysctl_tcp_mem 13 cgroup_sysctl sysctl_tcp_mem /sys/fs/cgroup/cg1/cg2 20 cgroup_sysctl sysctl_tcp_mem 6 cgroup_sysctl sysctl_tcp_mem 13 cgroup_sysctl sysctl_tcp_mem v3: - Don't show attach flags when effective query. (John, sdf, martin) v2: https://lore.kernel.org/bpf/20220908145304.3436139-1-pulehui@xxxxxxxxxxxxxxx - Limit prog_cnt to avoid overflow. (John) - Add more detail message. v1: https://lore.kernel.org/bpf/20220820120234.2121044-1-pulehui@xxxxxxxxxx Pu Lehui (2): bpf, cgroup: Don't populate prog_attach_flags array when effective query bpftool: Fix wrong cgroup attach flags being assigned to effective progs kernel/bpf/cgroup.c | 23 +++++++++------- tools/bpf/bpftool/cgroup.c | 54 +++++++++++++++++++++++--------------- 2 files changed, 46 insertions(+), 31 deletions(-) -- 2.25.1
