[RFC PATCH bpf-next 2/2] selftests/bpf: Add bpf link iter test

[Dmitrii Dolgov <9erthalion6@gmail.com>]

Add a simple test for bpf link iterator

Signed-off-by: Dmitrii Dolgov <9erthalion6@gmail.com>
---
 .../selftests/bpf/prog_tests/bpf_iter.c        | 15 +++++++++++++++
 .../selftests/bpf/progs/bpf_iter_bpf_link.c    | 18 ++++++++++++++++++
 2 files changed, 33 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_bpf_link.c

diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
index 2c403ddc8076..e14a7a6d925c 100644
--- a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
+++ b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
@@ -26,6 +26,7 @@
 #include "bpf_iter_bpf_sk_storage_map.skel.h"
 #include "bpf_iter_test_kern5.skel.h"
 #include "bpf_iter_test_kern6.skel.h"
+#include "bpf_iter_bpf_link.skel.h"
 
 static int duration;
 
@@ -1172,6 +1173,20 @@ static void test_buf_neg_offset(void)
 		bpf_iter_test_kern6__destroy(skel);
 }
 
+static void test_link_iter(void)
+{
+	struct bpf_iter_bpf_link *skel;
+
+	skel = bpf_iter_bpf_link__open_and_load();
+	if (CHECK(skel, "bpf_iter_bpf_link__open_and_load",
+		  "skeleton open_and_load unexpected success\n"))
+		return;
+
+	do_dummy_read(skel->progs.dump_bpf_link);
+
+	bpf_iter_bpf_link__destroy(skel);
+}
+
 #define CMP_BUFFER_SIZE 1024
 static char task_vma_output[CMP_BUFFER_SIZE];
 static char proc_maps_output[CMP_BUFFER_SIZE];
diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_bpf_link.c b/tools/testing/selftests/bpf/progs/bpf_iter_bpf_link.c
new file mode 100644
index 000000000000..a5041fa1cda9
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/bpf_iter_bpf_link.c
@@ -0,0 +1,18 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Facebook */
+#include "bpf_iter.h"
+#include <bpf/bpf_helpers.h>
+
+char _license[] SEC("license") = "GPL";
+
+SEC("iter/bpf_link")
+int dump_bpf_link(struct bpf_iter__bpf_link *ctx)
+{
+	struct seq_file *seq = ctx->meta->seq;
+	struct bpf_link *link = ctx->link;
+	int link_id;
+
+	link_id = link->id;
+	bpf_seq_write(seq, &link_id, sizeof(link_id));
+	return 0;
+}
-- 
2.32.0