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
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
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2.39.1
