Re: [PATCH bpf-next v6 3/4] bpf: Handle show_fdinfo for the parameterized task BPF iterators

Yonghong Song
2022-08-24T19:49:39Z

On 8/19/22 3:09 PM, Kui-Feng Lee wrote:
> Show information of iterators in the respective files under
> /proc/<pid>/fdinfo/.

Please show more information about what are dumped in
the commit message.

>
> Signed-off-by: Kui-Feng Lee <kuifeng@fb.com>
> ---
> kernel/bpf/task_iter.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c
> index 927b3a1cf354..5303eddb264b 100644
> --- a/kernel/bpf/task_iter.c
> +++ b/kernel/bpf/task_iter.c
> @@ -611,6 +611,11 @@ static int bpf_iter_fill_link_info(const struct bpf_iter_aux_info *aux, struct b
> return 0;
> }
>
> +static void bpf_iter_task_show_fdinfo(const struct bpf_iter_aux_info *aux, struct seq_file *seq)
> +{
> + seq_printf(seq, "task_type:\t%d\npid:\t%d\n", aux->task.type, aux->task.pid);

It would be good if we can print either 'tid: <number>' or 'pid:
<number>' instead of just 'pid: <number>' in all cases.
Also you don't need to print pid if it is 0 (to traverse all tasks).

We should use a string instead of an int for aux->task.type so user
doesn't need to look at kernel source which they may not have.

> +}
> +
> static struct bpf_iter_reg task_reg_info = {
> .target = "task",
> .attach_target = bpf_iter_attach_task,
> @@ -622,6 +627,7 @@ static struct bpf_iter_reg task_reg_info = {
> },
> .seq_info = &task_seq_info,
> .fill_link_info = bpf_iter_fill_link_info,
> + .show_fdinfo = bpf_iter_task_show_fdinfo,
> };
>
> static const struct bpf_iter_seq_info task_file_seq_info = {
> @@ -644,6 +650,7 @@ static struct bpf_iter_reg task_file_reg_info = {
> },
> .seq_info = &task_file_seq_info,
> .fill_link_info = bpf_iter_fill_link_info,
> + .show_fdinfo = bpf_iter_task_show_fdinfo,
> };
>
> static const struct bpf_iter_seq_info task_vma_seq_info = {
> @@ -666,6 +673,7 @@ static struct bpf_iter_reg task_vma_reg_info = {
> },
> .seq_info = &task_vma_seq_info,
> .fill_link_info = bpf_iter_fill_link_info,
> + .show_fdinfo = bpf_iter_task_show_fdinfo,
> };
>
> BPF_CALL_5(bpf_find_vma, struct task_struct *, task, u64, start,