From: Chuyi Zhou <zhouchuyi@bytedance.com>
To: bpf@vger.kernel.org
Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org,
martin.lau@kernel.org, tj@kernel.org,
linux-kernel@vger.kernel.org,
Chuyi Zhou <zhouchuyi@bytedance.com>
Subject: [PATCH bpf-next v4 4/8] bpf: Introduce css open-coded iterator kfuncs
Date: Sat, 7 Oct 2023 20:45:18 +0800 [thread overview]
Message-ID: <20231007124522.34834-5-zhouchuyi@bytedance.com> (raw)
In-Reply-To: <20231007124522.34834-1-zhouchuyi@bytedance.com>
This Patch adds kfuncs bpf_iter_css_{new,next,destroy} which allow
creation and manipulation of struct bpf_iter_css in open-coded iterator
style. These kfuncs actually wrapps css_next_descendant_{pre, post}.
css_iter can be used to:
1) iterating a sepcific cgroup tree with pre/post/up order
2) iterating cgroup_subsystem in BPF Prog, like
for_each_mem_cgroup_tree/cpuset_for_each_descendant_pre in kernel.
The API design is consistent with cgroup_iter. bpf_iter_css_new accepts
parameters defining iteration order and starting css. Here we also reuse
BPF_CGROUP_ITER_DESCENDANTS_PRE, BPF_CGROUP_ITER_DESCENDANTS_POST,
BPF_CGROUP_ITER_ANCESTORS_UP enums.
Signed-off-by: Chuyi Zhou <zhouchuyi@bytedance.com>
Acked-by: Tejun Heo <tj@kernel.org>
---
kernel/bpf/cgroup_iter.c | 59 +++++++++++++++++++
kernel/bpf/helpers.c | 3 +
.../testing/selftests/bpf/bpf_experimental.h | 6 ++
3 files changed, 68 insertions(+)
diff --git a/kernel/bpf/cgroup_iter.c b/kernel/bpf/cgroup_iter.c
index 810378f04fbc..9c6ad892ae82 100644
--- a/kernel/bpf/cgroup_iter.c
+++ b/kernel/bpf/cgroup_iter.c
@@ -294,3 +294,62 @@ static int __init bpf_cgroup_iter_init(void)
}
late_initcall(bpf_cgroup_iter_init);
+
+struct bpf_iter_css {
+ __u64 __opaque[3];
+} __attribute__((aligned(8)));
+
+struct bpf_iter_css_kern {
+ struct cgroup_subsys_state *start;
+ struct cgroup_subsys_state *pos;
+ unsigned int flags;
+} __attribute__((aligned(8)));
+
+__bpf_kfunc int bpf_iter_css_new(struct bpf_iter_css *it,
+ struct cgroup_subsys_state *start, unsigned int flags)
+{
+ struct bpf_iter_css_kern *kit = (void *)it;
+
+ BUILD_BUG_ON(sizeof(struct bpf_iter_css_kern) != sizeof(struct bpf_iter_css));
+ BUILD_BUG_ON(__alignof__(struct bpf_iter_css_kern) != __alignof__(struct bpf_iter_css));
+
+ kit->start = NULL;
+ switch (flags) {
+ case BPF_CGROUP_ITER_DESCENDANTS_PRE:
+ case BPF_CGROUP_ITER_DESCENDANTS_POST:
+ case BPF_CGROUP_ITER_ANCESTORS_UP:
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ kit->start = start;
+ kit->pos = NULL;
+ kit->flags = flags;
+ return 0;
+}
+
+__bpf_kfunc struct cgroup_subsys_state *bpf_iter_css_next(struct bpf_iter_css *it)
+{
+ struct bpf_iter_css_kern *kit = (void *)it;
+
+ if (!kit->start)
+ return NULL;
+
+ switch (kit->flags) {
+ case BPF_CGROUP_ITER_DESCENDANTS_PRE:
+ kit->pos = css_next_descendant_pre(kit->pos, kit->start);
+ break;
+ case BPF_CGROUP_ITER_DESCENDANTS_POST:
+ kit->pos = css_next_descendant_post(kit->pos, kit->start);
+ break;
+ case BPF_CGROUP_ITER_ANCESTORS_UP:
+ kit->pos = kit->pos ? kit->pos->parent : kit->start;
+ }
+
+ return kit->pos;
+}
+
+__bpf_kfunc void bpf_iter_css_destroy(struct bpf_iter_css *it)
+{
+}
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 8111437a999e..7596e83d6715 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -2555,6 +2555,9 @@ BTF_ID_FLAGS(func, bpf_iter_css_task_destroy, KF_ITER_DESTROY)
BTF_ID_FLAGS(func, bpf_iter_task_new, KF_ITER_NEW | KF_TRUSTED_ARGS)
BTF_ID_FLAGS(func, bpf_iter_task_next, KF_ITER_NEXT | KF_RET_NULL)
BTF_ID_FLAGS(func, bpf_iter_task_destroy, KF_ITER_DESTROY)
+BTF_ID_FLAGS(func, bpf_iter_css_new, KF_ITER_NEW | KF_TRUSTED_ARGS)
+BTF_ID_FLAGS(func, bpf_iter_css_next, KF_ITER_NEXT | KF_RET_NULL)
+BTF_ID_FLAGS(func, bpf_iter_css_destroy, KF_ITER_DESTROY)
BTF_ID_FLAGS(func, bpf_dynptr_adjust)
BTF_ID_FLAGS(func, bpf_dynptr_is_null)
BTF_ID_FLAGS(func, bpf_dynptr_is_rdonly)
diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h
index 1ec82997cce7..9aab609f6edd 100644
--- a/tools/testing/selftests/bpf/bpf_experimental.h
+++ b/tools/testing/selftests/bpf/bpf_experimental.h
@@ -463,4 +463,10 @@ extern int bpf_iter_task_new(struct bpf_iter_task *it,
extern struct task_struct *bpf_iter_task_next(struct bpf_iter_task *it) __weak __ksym;
extern void bpf_iter_task_destroy(struct bpf_iter_task *it) __weak __ksym;
+struct bpf_iter_css;
+extern int bpf_iter_css_new(struct bpf_iter_css *it,
+ struct cgroup_subsys_state *start, unsigned int flags) __weak __ksym;
+extern struct cgroup_subsys_state *bpf_iter_css_next(struct bpf_iter_css *it) __weak __ksym;
+extern void bpf_iter_css_destroy(struct bpf_iter_css *it) __weak __ksym;
+
#endif
--
2.20.1
next prev parent reply other threads:[~2023-10-07 12:46 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-07 12:45 [PATCH bpf-next v4 0/8] Add Open-coded task, css_task and css iters Chuyi Zhou
2023-10-07 12:45 ` [PATCH bpf-next v4 1/8] cgroup: Prepare for using css_task_iter_*() in BPF Chuyi Zhou
2023-10-07 12:45 ` [PATCH bpf-next v4 2/8] bpf: Introduce css_task open-coded iterator kfuncs Chuyi Zhou
2023-10-07 14:40 ` kernel test robot
2023-10-07 12:45 ` [PATCH bpf-next v4 3/8] bpf: Introduce task open coded " Chuyi Zhou
2023-10-07 15:22 ` kernel test robot
2023-10-07 12:45 ` Chuyi Zhou [this message]
2023-10-07 16:05 ` [PATCH bpf-next v4 4/8] bpf: Introduce css open-coded " kernel test robot
2023-10-11 4:44 ` Chuyi Zhou
2023-10-11 5:32 ` Chuyi Zhou
2023-10-07 12:45 ` [PATCH bpf-next v4 5/8] bpf: teach the verifier to enforce css_iter and task_iter in RCU CS Chuyi Zhou
2023-10-07 12:45 ` [PATCH bpf-next v4 6/8] bpf: Let bpf_iter_task_new accept null task ptr Chuyi Zhou
2023-10-07 12:45 ` [PATCH bpf-next v4 7/8] selftests/bpf: rename bpf_iter_task.c to bpf_iter_tasks.c Chuyi Zhou
2023-10-07 12:45 ` [PATCH bpf-next v4 8/8] selftests/bpf: Add tests for open-coded task and css iter Chuyi Zhou
2023-10-10 8:01 ` [PATCH bpf-next v4 0/8] Add Open-coded task, css_task and css iters Daniel Borkmann
2023-10-10 8:14 ` Chuyi Zhou
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