On Tue, Nov 24, 2020 at 1:03 AM Daniel T. Lee <danieltimlee@xxxxxxxxx> wrote:
>
> This commit refactors the existing cgroup programs with libbpf
> bpf loader. Since bpf_program__attach doesn't support cgroup program
> attachment, this explicitly attaches cgroup bpf program with
> bpf_program__attach_cgroup(bpf_prog, cg1).
>
> Also, to change attach_type of bpf program, this uses libbpf's
> bpf_program__set_expected_attach_type helper to switch EGRESS to
> INGRESS. To keep bpf program attached to the cgroup hierarchy even
> after the exit, this commit uses the BPF_LINK_PINNING to pin the link
> attachment even after it is closed.
>
> Besides, this program was broken due to the typo of BPF MAP definition.
> But this commit solves the problem by fixing this from 'queue_stats' map
> struct hvm_queue_stats -> hbm_queue_stats.
>
> Fixes: 36b5d471135c ("selftests/bpf: samples/bpf: Split off legacy stuff from bpf_helpers.h")
> Signed-off-by: Daniel T. Lee <danieltimlee@xxxxxxxxx>
> ---
> Changes in v2:
> - restore read_trace_pipe2
> - remove unnecessary return code and cgroup fd compare
> - add static at global variable and remove unused variable
> - change cgroup path with unified controller (/unified/)
> - add link pinning to prevent cleaning up on process exit
>
> Changes in v3:
> - cleanup bpf_link, bpf_object and cgroup fd both on success and error
> - remove link NULL cleanup since __destroy() can handle
> - fix cgroup test on cgroup fd cleanup
>
> samples/bpf/.gitignore | 3 +
> samples/bpf/Makefile | 2 +-
> samples/bpf/do_hbm_test.sh | 32 +++++------
> samples/bpf/hbm.c | 111 ++++++++++++++++++++-----------------
> samples/bpf/hbm_kern.h | 2 +-
> 5 files changed, 78 insertions(+), 72 deletions(-)
>
Thanks for the nice clean up! I've applied the series to bpf-next. If
Martin finds any other problems, those can be fixed in a follow up
patch(es). But see also below about find_program_by_title().
> - if (ret) {
> - printf("ERROR: bpf_prog_load_xattr failed for: %s\n", prog);
> - printf(" Output from verifier:\n%s\n------\n", bpf_log_buf);
> - ret = -1;
> - } else {
> - ret = map_fd;
> + bpf_prog = bpf_object__find_program_by_title(obj, "cgroup_skb/egress");
It would be good to avoid using find_program_by_title(), as it's going
to get deprecated and eventually removed. Looking up by section name
("title") is ambiguous now that libbpf supports many BPF programs per
same section. There is find_program_by_name() which looks program by
its C function name. I suggest using it.
> + if (!bpf_prog) {
> + printf("ERROR: finding a prog in obj file failed\n");
> + goto err;
> + }
> +
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