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

[Yafang Shao <laoar.shao@xxxxxxxxx>]

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));
+	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