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[bpf-next,2/4] bpf: Add bpf_iter_cpumask kfuncs

Message ID 20231222113102.4148-3-laoar.shao@gmail.com (mailing list archive)
State Changes Requested
Delegated to: BPF
Headers show
Series bpf: Add bpf_iter_cpumask | expand

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Commit Message

Yafang Shao Dec. 22, 2023, 11:31 a.m. UTC 
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@gmail.com>
---
 kernel/bpf/cpumask.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

Comments

Andrii Nakryiko Jan. 2, 2024, 10:13 p.m. UTC | #1 
On Fri, Dec 22, 2023 at 3:31 AM Yafang Shao <laoar.shao@gmail.com> 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@gmail.com>
> ---
>  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
>
Yafang Shao Jan. 4, 2024, 2:30 a.m. UTC | #2 
On Wed, Jan 3, 2024 at 6:13 AM Andrii Nakryiko
<andrii.nakryiko@gmail.com> wrote:
>
> On Fri, Dec 22, 2023 at 3:31 AM Yafang Shao <laoar.shao@gmail.com> 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@gmail.com>
> > ---
> >  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?

Will do it. Thanks for your suggestion.
diff mbox series

Patch

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));
+	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 = {