Re: [PATCH bpf-next v9 0/5] Parameterize task iterators.

Jiri Olsa
2022-08-31T11:32:36Z

On Tue, Aug 30, 2022 at 07:37:39PM -0700, Kui-Feng Lee wrote:
> Allow creating an iterator that loops through resources of one task/thread.
>
> People could only create iterators to loop through all resources of
> files, vma, and tasks in the system, even though they were interested in only the
> resources of a specific task or process. Passing the additional
> parameters, people can now create an iterator to go through all
> resources or only the resources of a task.
>
> Major Changes:
>
> - Add new parameters in bpf_iter_link_info to indicate to go through
> all tasks or to go through a specific task.
>
> - Change the implementations of BPF iterators of vma, files, and
> tasks to allow going through only the resources of a specific task.
>
> - Provide the arguments of parameterized task iterators in
> bpf_link_info.

hi,
I'm getting bpf_iter/vma_offset fail:

test_task_vma_offset_common:PASS:bpf_iter_vma_offset__open_and_load 0 nsec
test_task_vma_offset_common:PASS:attach_iter 0 nsec
test_task_vma_offset_common:PASS:create_iter 0 nsec
test_task_vma_offset_common:PASS:strcmp 0 nsec
test_task_vma_offset_common:FAIL:offset unexpected offset: actual 257222 != expected 203974
test_task_vma_offset_common:PASS:unique_tgid_count 0 nsec
test_task_vma_offset_common:PASS:bpf_iter_vma_offset__open_and_load 0 nsec
test_task_vma_offset_common:PASS:attach_iter 0 nsec
test_task_vma_offset_common:PASS:create_iter 0 nsec
test_task_vma_offset_common:PASS:strcmp 0 nsec
test_task_vma_offset_common:FAIL:offset unexpected offset: actual 257222 != expected 203974
test_task_vma_offset_common:PASS:unique_tgid_count 0 nsec
test_task_vma_offset_common:PASS:bpf_iter_vma_offset__open_and_load 0 nsec
test_task_vma_offset_common:PASS:attach_iter 0 nsec
test_task_vma_offset_common:PASS:create_iter 0 nsec
test_task_vma_offset_common:PASS:strcmp 0 nsec
test_task_vma_offset_common:FAIL:offset unexpected offset: actual 257222 != expected 203974
test_task_vma_offset_common:PASS:unique_tgid_count 0 nsec
#11/38 bpf_iter/vma_offset:FAIL

jirka

>
> Differences from v8:
>
> - Fix uninitialized variable.
>
> - Avoid redundant work of getting task from pid.
>
> - Change format string to use %u instead of %d.
>
> - Use the value of page_shift to compute correct offset in
> bpf_iter_vm_offset.c.
>
> Differences from v7:
>
> - Travel the tasks of a process through task_group linked list
> instead of traveling through the whole namespace.
>
> Differences from v6:
>
> - Add part 5 to make bpftool show the value of parameters.
>
> - Change of wording of show_fdinfo() to show pid or tid instead of
> always pid.
>
> - Simplify error handling and naming of test cases.
>
> Differences from v5:
>
> - Use user-space tid/pid terminologies in bpf_iter_link_info and
> bpf_link_info.
>
> - Fix reference count
>
> - Merge all variants to one 'u32 pid' in internal structs.
> (bpf_iter_aux_info and bpf_iter_seq_task_common)
>
> - Compare the result of get_uprobe_offset() with the implementation
> with the vma iterators.
>
> - Implement show_fdinfo.
>
> Differences from v4:
>
> - Remove 'type' from bpf_iter_link_info and bpf_link_info.
>
> v8: https://lore.kernel.org/bpf/20220829192317.486946-1-kuifeng@fb.com/
> v7: https://lore.kernel.org/bpf/20220826003712.2810158-1-kuifeng@fb.com/
> v6: https://lore.kernel.org/bpf/20220819220927.3409575-1-kuifeng@fb.com/
> v5: https://lore.kernel.org/bpf/20220811001654.1316689-1-kuifeng@fb.com/
> v4: https://lore.kernel.org/bpf/20220809195429.1043220-1-kuifeng@fb.com/
> v3: https://lore.kernel.org/bpf/20220809063501.667610-1-kuifeng@fb.com/
> v2: https://lore.kernel.org/bpf/20220801232649.2306614-1-kuifeng@fb.com/
> v1: https://lore.kernel.org/bpf/20220726051713.840431-1-kuifeng@fb.com/
>
> Kui-Feng Lee (5):
> bpf: Parameterize task iterators.
> bpf: Handle bpf_link_info for the parameterized task BPF iterators.
> bpf: Handle show_fdinfo for the parameterized task BPF iterators
> selftests/bpf: Test parameterized task BPF iterators.
> bpftool: Show parameters of BPF task iterators.
>
> include/linux/bpf.h | 25 ++
> include/uapi/linux/bpf.h | 10 +
> kernel/bpf/task_iter.c | 227 ++++++++++++--
> tools/bpf/bpftool/link.c | 19 ++
> tools/include/uapi/linux/bpf.h | 10 +
> .../selftests/bpf/prog_tests/bpf_iter.c | 282 ++++++++++++++++--
> .../selftests/bpf/prog_tests/btf_dump.c | 2 +-
> .../selftests/bpf/progs/bpf_iter_task.c | 9 +
> .../selftests/bpf/progs/bpf_iter_task_file.c | 9 +-
> .../selftests/bpf/progs/bpf_iter_task_vma.c | 7 +-
> .../selftests/bpf/progs/bpf_iter_vma_offset.c | 37 +++
> 11 files changed, 591 insertions(+), 46 deletions(-)
> create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_vma_offset.c
>
> --
> 2.30.2
>