[PATCH net-next 32/33] selftests/bpf: adjust BPF selftest for xdp_adjust_tail

[Jesper Dangaard Brouer <brouer@redhat.com>]

Current selftest for BPF-helper xdp_adjust_tail only shrink tail.
Make it more clear that this is a shrink test case.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
---
 .../selftests/bpf/prog_tests/xdp_adjust_tail.c     |    9 +++++-
 .../testing/selftests/bpf/progs/test_adjust_tail.c |   30 --------------------
 .../bpf/progs/test_xdp_adjust_tail_shrink.c        |   30 ++++++++++++++++++++
 3 files changed, 37 insertions(+), 32 deletions(-)
 delete mode 100644 tools/testing/selftests/bpf/progs/test_adjust_tail.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_xdp_adjust_tail_shrink.c

diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_adjust_tail.c b/tools/testing/selftests/bpf/prog_tests/xdp_adjust_tail.c
index 3744196d7cba..d258f979d5ef 100644
--- a/tools/testing/selftests/bpf/prog_tests/xdp_adjust_tail.c
+++ b/tools/testing/selftests/bpf/prog_tests/xdp_adjust_tail.c
@@ -1,9 +1,9 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <test_progs.h>
 
-void test_xdp_adjust_tail(void)
+void test_xdp_adjust_tail_shrink(void)
 {
-	const char *file = "./test_adjust_tail.o";
+	const char *file = "./test_xdp_adjust_tail_shrink.o";
 	struct bpf_object *obj;
 	char buf[128];
 	__u32 duration, retval, size;
@@ -27,3 +27,8 @@ void test_xdp_adjust_tail(void)
 	      err, errno, retval, size);
 	bpf_object__close(obj);
 }
+
+void test_xdp_adjust_tail(void)
+{
+	test_xdp_adjust_tail_shrink();
+}
diff --git a/tools/testing/selftests/bpf/progs/test_adjust_tail.c b/tools/testing/selftests/bpf/progs/test_adjust_tail.c
deleted file mode 100644
index b7fc85769bdc..000000000000
--- a/tools/testing/selftests/bpf/progs/test_adjust_tail.c
+++ /dev/null
@@ -1,30 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0
- * Copyright (c) 2018 Facebook
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of version 2 of the GNU General Public
- * License as published by the Free Software Foundation.
- */
-#include <linux/bpf.h>
-#include <linux/if_ether.h>
-#include <bpf/bpf_helpers.h>
-
-int _version SEC("version") = 1;
-
-SEC("xdp_adjust_tail")
-int _xdp_adjust_tail(struct xdp_md *xdp)
-{
-	void *data_end = (void *)(long)xdp->data_end;
-	void *data = (void *)(long)xdp->data;
-	int offset = 0;
-
-	if (data_end - data == 54)
-		offset = 256;
-	else
-		offset = 20;
-	if (bpf_xdp_adjust_tail(xdp, 0 - offset))
-		return XDP_DROP;
-	return XDP_TX;
-}
-
-char _license[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/progs/test_xdp_adjust_tail_shrink.c b/tools/testing/selftests/bpf/progs/test_xdp_adjust_tail_shrink.c
new file mode 100644
index 000000000000..c8a7c17b54f4
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_xdp_adjust_tail_shrink.c
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0
+ * Copyright (c) 2018 Facebook
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ */
+#include <linux/bpf.h>
+#include <linux/if_ether.h>
+#include <bpf/bpf_helpers.h>
+
+int _version SEC("version") = 1;
+
+SEC("xdp_adjust_tail_shrink")
+int _xdp_adjust_tail_shrink(struct xdp_md *xdp)
+{
+	void *data_end = (void *)(long)xdp->data_end;
+	void *data = (void *)(long)xdp->data;
+	int offset = 0;
+
+	if (data_end - data == 54) /* sizeof(pkt_v4) */
+		offset = 256; /* shrink too much */
+	else
+		offset = 20;
+	if (bpf_xdp_adjust_tail(xdp, 0 - offset))
+		return XDP_DROP;
+	return XDP_TX;
+}
+
+char _license[] SEC("license") = "GPL";