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:
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 | 34 ++++++++---
kernel/bpf/syscall.c | 2 +-
net/core/bpf_sk_storage.c | 34 ++++++++---
tools/bpf/bpftool/iter.c | 8 ++-
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 | 4 +-
.../selftests/bpf/prog_tests/bpf_iter.c | 34 ++++++++---
13 files changed, 146 insertions(+), 81 deletions(-)
--
2.24.1
