From 01e0120220e489f147fd4e91d1bde5393f14b4ff Mon Sep 17 00:00:00 2001
From: Dylan Yudaken <dylany@fb.com>
Date: Mon, 13 Jun 2022 06:12:53 -0700
Subject: buf-ring: add tests that cycle through the provided buffer ring

Add tests that make sure that the buffer ring logic works properly
without actually using the data in each buffer.

This exposes some bugs in 5.19-rc1

Signed-off-by: Dylan Yudaken <dylany@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 test/buf-ring.c | 133 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 133 insertions(+)

diff --git a/test/buf-ring.c b/test/buf-ring.c
index 5fd1e53..2fcc360 100644
--- a/test/buf-ring.c
+++ b/test/buf-ring.c
@@ -206,9 +206,134 @@ static int test_reg_unreg(int bgid)
 	return 0;
 }
 
+static int test_one_nop(int bgid, struct io_uring *ring)
+{
+	int ret;
+	struct io_uring_cqe *cqe;
+	struct io_uring_sqe *sqe;
+
+	sqe = io_uring_get_sqe(ring);
+	if (!sqe) {
+		fprintf(stderr, "get sqe failed\n");
+		return -1;
+	}
+
+	io_uring_prep_nop(sqe);
+	sqe->flags |= IOSQE_BUFFER_SELECT;
+	sqe->buf_group = bgid;
+	ret = io_uring_submit(ring);
+	if (ret <= 0) {
+		fprintf(stderr, "sqe submit failed: %d\n", ret);
+		ret = -1;
+		goto out;
+	}
+
+	ret = io_uring_wait_cqe(ring, &cqe);
+	if (ret < 0) {
+		fprintf(stderr, "wait completion %d\n", ret);
+		ret = -1;
+		goto out;
+	}
+
+	if (cqe->res == -ENOBUFS) {
+		ret = cqe->res;
+		goto out;
+	}
+
+	if (cqe->res != 0) {
+		fprintf(stderr, "nop result %d\n", ret);
+		ret = -1;
+		goto out;
+	}
+
+	ret = cqe->flags >> 16;
+
+out:
+	io_uring_cqe_seen(ring, cqe);
+	return ret;
+}
+
+static int test_running(int bgid, int entries, int loops)
+{
+	struct io_uring_buf_reg reg = { };
+	struct io_uring ring;
+	void *ptr;
+	int ret;
+	int ring_size = (entries * sizeof(struct io_uring_buf) + 4095) & (~4095);
+	int ring_mask = io_uring_buf_ring_mask(entries);
+
+	int loop, idx;
+	bool *buffers;
+	struct io_uring_buf_ring *br;
+
+	ret = t_create_ring(1, &ring, 0);
+	if (ret == T_SETUP_SKIP)
+		return 0;
+	else if (ret != T_SETUP_OK)
+		return 1;
+
+	if (posix_memalign(&ptr, 4096, ring_size))
+		return 1;
+
+	br = (struct io_uring_buf_ring *)ptr;
+	io_uring_buf_ring_init(br);
+
+	buffers = malloc(sizeof(bool) * entries);
+	if (!buffers)
+		return 1;
+
+	reg.ring_addr = (unsigned long) ptr;
+	reg.ring_entries = entries;
+	reg.bgid = bgid;
+
+	ret = io_uring_register_buf_ring(&ring, &reg, 0);
+	if (ret) {
+		/* by now should have checked if this is supported or not */
+		fprintf(stderr, "Buffer ring register failed %d\n", ret);
+		return 1;
+	}
+
+	for (loop = 0; loop < loops; loop++) {
+		memset(buffers, 0, sizeof(bool) * entries);
+		for (idx = 0; idx < entries; idx++)
+			io_uring_buf_ring_add(br, ptr, 1, idx, ring_mask, idx);
+		io_uring_buf_ring_advance(br, entries);
+
+		for (idx = 0; idx < entries; idx++) {
+			ret = test_one_nop(bgid, &ring);
+			if (ret < 0) {
+				fprintf(stderr, "bad run %d/%d = %d\n", loop, idx, ret);
+				return ret;
+			}
+			if (buffers[ret]) {
+				fprintf(stderr, "reused buffer %d/%d = %d!\n", loop, idx, ret);
+				return 1;
+			}
+			buffers[ret] = true;
+		}
+		ret = test_one_nop(bgid, &ring);
+		if (ret != -ENOBUFS) {
+			fprintf(stderr, "expected enobufs run %d = %d\n", loop, ret);
+			return 1;
+		}
+
+	}
+
+	ret = io_uring_unregister_buf_ring(&ring, bgid);
+	if (ret) {
+		fprintf(stderr, "Buffer ring register failed %d\n", ret);
+		return 1;
+	}
+
+	io_uring_queue_exit(&ring);
+	free(buffers);
+	return 0;
+}
+
 int main(int argc, char *argv[])
 {
 	int bgids[] = { 1, 127, -1 };
+	int entries[] = {1, 32768, 4096, -1 };
 	int ret, i;
 
 	if (argc > 1)
@@ -242,5 +367,13 @@ int main(int argc, char *argv[])
 		}
 	}
 
+	for (i = 0; !no_buf_ring && entries[i] != -1; i++) {
+		ret = test_running(2, entries[i], 3);
+		if (ret) {
+			fprintf(stderr, "test_running(%d) failed\n", entries[i]);
+			return 1;
+		}
+	}
+
 	return 0;
 }
-- 
cgit v1.2.3