selftests/bpf: Test cgroup_iter.
Add a selftest for cgroup_iter. The selftest creates a mini cgroup tree
of the following structure:
ROOT (working cgroup)
|
PARENT
/ \
CHILD1 CHILD2
and tests the following scenarios:
- invalid cgroup fd.
- pre-order walk over descendants from PARENT.
- post-order walk over descendants from PARENT.
- walk of ancestors from PARENT.
- process only a single object (i.e. PARENT).
- early termination.
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Hao Luo <haoluo@google.com>
Link: https://lore.kernel.org/r/20220824233117.1312810-3-haoluo@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
diff --git a/tools/testing/selftests/bpf/progs/cgroup_iter.c b/tools/testing/selftests/bpf/progs/cgroup_iter.c
new file mode 100644
index 0000000..de03997
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/cgroup_iter.c
@@ -0,0 +1,39 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022 Google */
+
+#include "bpf_iter.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+int terminate_early = 0;
+u64 terminal_cgroup = 0;
+
+static inline u64 cgroup_id(struct cgroup *cgrp)
+{
+ return cgrp->kn->id;
+}
+
+SEC("iter/cgroup")
+int cgroup_id_printer(struct bpf_iter__cgroup *ctx)
+{
+ struct seq_file *seq = ctx->meta->seq;
+ struct cgroup *cgrp = ctx->cgroup;
+
+ /* epilogue */
+ if (cgrp == NULL) {
+ BPF_SEQ_PRINTF(seq, "epilogue\n");
+ return 0;
+ }
+
+ /* prologue */
+ if (ctx->meta->seq_num == 0)
+ BPF_SEQ_PRINTF(seq, "prologue\n");
+
+ BPF_SEQ_PRINTF(seq, "%8llu\n", cgroup_id(cgrp));
+
+ if (terminal_cgroup == cgroup_id(cgrp))
+ return 1;
+
+ return terminate_early ? 1 : 0;
+}
