On Fri, Dec 22, 2023 at 3:31 AM Yafang Shao <laoar.shao@xxxxxxxxx> wrote:
>
> Add three new kfuncs for bpf_iter_cpumask.
> - bpf_iter_cpumask_new
> - bpf_iter_cpumask_next
> - bpf_iter_cpumask_destroy
>
> These new kfuncs facilitate the iteration of percpu data, such as
> runqueues, psi_cgroup_cpu, and more.
>
> Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx>
> ---
> kernel/bpf/cpumask.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 48 insertions(+)
>
> diff --git a/kernel/bpf/cpumask.c b/kernel/bpf/cpumask.c
> index 2e73533..4ae07a4 100644
> --- a/kernel/bpf/cpumask.c
> +++ b/kernel/bpf/cpumask.c
> @@ -422,6 +422,51 @@ __bpf_kfunc u32 bpf_cpumask_weight(const struct cpumask *cpumask)
> return cpumask_weight(cpumask);
> }
>
> +struct bpf_iter_cpumask {
> + __u64 __opaque[2];
> +} __aligned(8);
> +
> +struct bpf_iter_cpumask_kern {
> + struct cpumask *mask;
> + int *cpu;
> +} __aligned(8);
> +
> +__bpf_kfunc u32 bpf_iter_cpumask_new(struct bpf_iter_cpumask *it, struct cpumask *mask)
> +{
> + struct bpf_iter_cpumask_kern *kit = (void *)it;
> +
> + kit->cpu = bpf_mem_alloc(&bpf_global_ma, sizeof(*kit->cpu));
why dynamic memory allocation of 4 bytes?... just have `int cpu;`
field in bpf_iter_cpumask_kern?
> + if (!kit->cpu)
> + return -ENOMEM;
> +
> + kit->mask = mask;
> + *kit->cpu = -1;
> + return 0;
> +}
> +
> +__bpf_kfunc int *bpf_iter_cpumask_next(struct bpf_iter_cpumask *it)
> +{
> + struct bpf_iter_cpumask_kern *kit = (void *)it;
> + struct cpumask *mask = kit->mask;
> + int cpu;
> +
> + cpu = cpumask_next(*kit->cpu, mask);
> + if (cpu >= nr_cpu_ids)
> + return NULL;
> +
> + *kit->cpu = cpu;
> + return kit->cpu;
> +}
> +
> +__bpf_kfunc void bpf_iter_cpumask_destroy(struct bpf_iter_cpumask *it)
> +{
> + struct bpf_iter_cpumask_kern *kit = (void *)it;
> +
> + if (!kit->cpu)
> + return;
> + bpf_mem_free(&bpf_global_ma, kit->cpu);
> +}
> +
> __bpf_kfunc_end_defs();
>
> BTF_SET8_START(cpumask_kfunc_btf_ids)
> @@ -450,6 +495,9 @@ __bpf_kfunc u32 bpf_cpumask_weight(const struct cpumask *cpumask)
> BTF_ID_FLAGS(func, bpf_cpumask_any_distribute, KF_RCU)
> BTF_ID_FLAGS(func, bpf_cpumask_any_and_distribute, KF_RCU)
> BTF_ID_FLAGS(func, bpf_cpumask_weight, KF_RCU)
> +BTF_ID_FLAGS(func, bpf_iter_cpumask_new, KF_ITER_NEW | KF_RCU)
> +BTF_ID_FLAGS(func, bpf_iter_cpumask_next, KF_ITER_NEXT | KF_RET_NULL | KF_RCU)
> +BTF_ID_FLAGS(func, bpf_iter_cpumask_destroy, KF_ITER_DESTROY)
> BTF_SET8_END(cpumask_kfunc_btf_ids)
>
> static const struct btf_kfunc_id_set cpumask_kfunc_set = {
> --
> 1.8.3.1
>
