On Mon, Aug 3, 2020 at 3:44 PM Yonghong Song <yhs@xxxxxx> wrote: > > Andrii raised a concern that current uapi for bpf iterator map > element is a little restrictive and not suitable for future potential > complex customization. This is a valid suggestion, considering people > may indeed add more complex custimization to the iterator, e.g., > cgroup_id + user_id, etc. for task or task_file. Another example might > be map_id plus additional control so that the bpf iterator may bail > out a bucket earlier if a bucket has too many elements which may hold > lock too long and impact other parts of systems. > > Patch #1 modified uapi with kernel changes. Patch #2 > adjusted libbpf api accordingly. > > Changelogs: > v2 -> v3: > . undo "not reject iter_info.map.map_fd == 0" from v1. > In the future map_fd may become optional, so let us use map_fd == 0 > indicating the map_fd is not set by user space. > . add link_info_len to bpf_iter_attach_opts to ensure always correct > link_info_len from user. Otherwise, libbpf may deduce incorrect > link_info_len if it uses different uapi header than the user app. > v1 -> v2: > . ensure link_create target_fd/flags == 0 since they are not used. (Andrii) > . if either of iter_info ptr == 0 or iter_info_len == 0, but not both, > return error to user space. (Andrii) > . do not reject iter_info.map.map_fd == 0, go ahead to use it trying to > get a map reference since the map_fd is required for map_elem iterator. > . use bpf_iter_link_info in bpf_iter_attach_opts instead of map_fd. > this way, user space is responsible to set up bpf_iter_link_info and > libbpf just passes the data to the kernel, simplifying libbpf design. > (Andrii) > > Yonghong Song (2): > bpf: change uapi for bpf iterator map elements > tools/bpf: support new uapi for map element bpf iterator > > include/linux/bpf.h | 10 ++-- > include/uapi/linux/bpf.h | 15 ++--- > kernel/bpf/bpf_iter.c | 58 +++++++++---------- > kernel/bpf/map_iter.c | 37 +++++++++--- > kernel/bpf/syscall.c | 2 +- > net/core/bpf_sk_storage.c | 37 +++++++++--- > tools/bpf/bpftool/iter.c | 9 ++- > tools/include/uapi/linux/bpf.h | 15 ++--- > tools/lib/bpf/bpf.c | 3 + > tools/lib/bpf/bpf.h | 4 +- > tools/lib/bpf/libbpf.c | 6 +- > tools/lib/bpf/libbpf.h | 5 +- > .../selftests/bpf/prog_tests/bpf_iter.c | 40 ++++++++++--- > 13 files changed, 159 insertions(+), 82 deletions(-) > > -- > 2.24.1 > Looks great, thanks! Acked-by: Andrii Nakryiko <andriin@xxxxxx>
