1 files changed, 46 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/progs/test_ringbuf_write.c b/tools/testing/selftests/bpf/progs/test_ringbuf_write.c
new file mode 100644
index 000000000000..350513c0e4c9
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_ringbuf_write.c
@@ -0,0 +1,46 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+
+char _license[] SEC("license") = "GPL";
+
+struct {
+	__uint(type, BPF_MAP_TYPE_RINGBUF);
+} ringbuf SEC(".maps");
+
+/* inputs */
+int pid = 0;
+
+/* outputs */
+long passed = 0;
+long discarded = 0;
+
+SEC("fentry/" SYS_PREFIX "sys_getpgid")
+int test_ringbuf_write(void *ctx)
+{
+	int *foo, cur_pid = bpf_get_current_pid_tgid() >> 32;
+	void *sample1, *sample2;
+
+	if (cur_pid != pid)
+		return 0;
+
+	sample1 = bpf_ringbuf_reserve(&ringbuf, 0x3000, 0);
+	if (!sample1)
+		return 0;
+	/* first one can pass */
+	sample2 = bpf_ringbuf_reserve(&ringbuf, 0x3000, 0);
+	if (!sample2) {
+		bpf_ringbuf_discard(sample1, 0);
+		__sync_fetch_and_add(&discarded, 1);
+		return 0;
+	}
+	/* second one must not */
+	__sync_fetch_and_add(&passed, 1);
+	foo = sample2 + 4084;
+	*foo = 256;
+	bpf_ringbuf_discard(sample1, 0);
+	bpf_ringbuf_discard(sample2, 0);
+	return 0;
+}