[PATCH bpf-next 4/4] selftests/bpf: Add tests for attaching XDP programs

["Toke Høiland-Jørgensen" <toke@redhat.com>]

From: Toke Høiland-Jørgensen <toke@redhat.com>

This adds tests for the various replacement operations using
IFLA_XDP_EXPECTED_FD.

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
---
 .../testing/selftests/bpf/prog_tests/xdp_attach.c  |   55 ++++++++++++++++++++
 1 file changed, 55 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/xdp_attach.c

diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_attach.c b/tools/testing/selftests/bpf/prog_tests/xdp_attach.c
new file mode 100644
index 000000000000..ad974b677e74
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/xdp_attach.c
@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <test_progs.h>
+
+#define IFINDEX_LO 1
+
+void test_xdp_attach(void)
+{
+	struct bpf_object *obj1, *obj2, *obj3;
+	const char *file = "./test_xdp.o";
+	int err, fd1, fd2, fd3;
+        __u32 duration = 0;
+
+	err = bpf_prog_load(file, BPF_PROG_TYPE_XDP, &obj1, &fd1);
+	if (CHECK_FAIL(err))
+		return;
+	err = bpf_prog_load(file, BPF_PROG_TYPE_XDP, &obj2, &fd2);
+	if (CHECK_FAIL(err))
+		goto out_1;
+	err = bpf_prog_load(file, BPF_PROG_TYPE_XDP, &obj3, &fd3);
+	if (CHECK_FAIL(err))
+		goto out_2;
+
+        err = bpf_set_link_xdp_fd_replace(IFINDEX_LO, fd1, -1, 0);
+        if (CHECK(err, "load_ok", "initial load failed"))
+                goto out_close;
+
+        err = bpf_set_link_xdp_fd_replace(IFINDEX_LO, fd2, -1, 0);
+        if (CHECK(!err, "load_fail", "load with expected fd didn't fail"))
+                goto out;
+
+        err = bpf_set_link_xdp_fd_replace(IFINDEX_LO, fd2, fd1, 0);
+        if (CHECK(err, "replace_ok", "replace valid old_fd failed"))
+                goto out;
+
+        err = bpf_set_link_xdp_fd_replace(IFINDEX_LO, fd3, fd1, 0);
+        if (CHECK(!err, "replace_fail", "replace invalid old_fd didn't fail"))
+                goto out;
+
+        err = bpf_set_link_xdp_fd_replace(IFINDEX_LO, -1, fd1, 0);
+        if (CHECK(!err, "remove_fail", "remove invalid old_fd didn't fail"))
+                goto out;
+
+        err = bpf_set_link_xdp_fd_replace(IFINDEX_LO, -1, fd2, 0);
+        if (CHECK(err, "remove_ok", "remove valid old_fd failed"))
+                goto out;
+
+out:
+        bpf_set_link_xdp_fd(IFINDEX_LO, -1, 0);
+out_close:
+	bpf_object__close(obj3);
+out_2:
+	bpf_object__close(obj2);
+out_1:
+	bpf_object__close(obj1);
+}