On Tue, Feb 6, 2024 at 12:14 AM Yafang Shao <laoar.shao@xxxxxxxxx> wrote:
>
> Three new kfuncs, namely bpf_iter_cpumask_{new,next,destroy}, have been
> added for the new bpf_iter_cpumask functionality. These kfuncs enable the
> iteration of percpu data, such as runqueues, system_group_pcpu, and more.
>
> In our specific use case, we leverage the cgroup iterator to traverse
> percpu data, subsequently exposing it to userspace through a seq file.
> Refer to example in patch #2 for the usage.
>
> Changes:
> - v5 -> v6:
> - Various improvements on the comments (Andrii)
> - Use a static function instead as Kumar's patch[0] has been merged.
> (Anrii, Yonghong)
>
> [0]. https://lore.kernel.org/bpf/170719262630.31872.2248639771567354367.git-patchwork-notify@xxxxxxxxxx
>
> - v4 -> v5:
> - Use cpumask_size() instead of sizeof(struct cpumask) (David)
> - Refactor the selftests as suggsted by David
> - Improve the doc as suggested by David
> - v3 -> v4:
> - Use a copy of cpumask to avoid potential use-after-free (Yonghong)
> - Various code improvement in selftests (Yonghong)
> - v2 -> v3:
> - Define KF_RCU_PROTECTED for bpf_iter_cpumask_new (Alexei)
> - Code improvement in selftests
> - Fix build error in selftest due to CONFIG_PSI=n
> reported by kernel test robot <lkp@xxxxxxxxx>
> - v1 -> v2:
> - Avoid changing cgroup subsystem (Tejun)
> - Remove bpf_cpumask_set_from_pid(), and use bpf_cpumask_copy()
> instead (Tejun)
> - Use `int cpu;` field in bpf_iter_cpumask_kern (Andrii)
>
> Yafang Shao (5):
> bpf: Add bpf_iter_cpumask kfuncs
> bpf, docs: Add document for cpumask iter
> selftests/bpf: Fix error checking for cpumask_success__load()
> selftests/bpf: Mark cpumask kfunc declarations as __weak
I've applied patches 3 and 4, as they are general clean ups and
improvements independent from the actual iterator implementation.
Thanks!
> selftests/bpf: Add selftests for cpumask iter
>
> Documentation/bpf/cpumasks.rst | 60 +++++++
> kernel/bpf/cpumask.c | 79 +++++++++
> tools/testing/selftests/bpf/config | 1 +
> .../selftests/bpf/prog_tests/cpumask.c | 158 +++++++++++++++++-
> .../selftests/bpf/progs/cpumask_common.h | 60 +++----
> .../bpf/progs/cpumask_iter_failure.c | 99 +++++++++++
> .../bpf/progs/cpumask_iter_success.c | 126 ++++++++++++++
> 7 files changed, 552 insertions(+), 31 deletions(-)
> create mode 100644 tools/testing/selftests/bpf/progs/cpumask_iter_failure.c
> create mode 100644 tools/testing/selftests/bpf/progs/cpumask_iter_success.c
>
> --
> 2.39.1
>
