[PATCH v2 liburing 6/7] add poll overflow test

[Dylan Yudaken <dylany@fb.com>]

Add a test that when CQE overflows, multishot poll doesn't give
out of order completions.

Signed-off-by: Dylan Yudaken <dylany@fb.com>
---
 test/Makefile              |   1 +
 test/poll-mshot-overflow.c | 128 +++++++++++++++++++++++++++++++++++++
 2 files changed, 129 insertions(+)
 create mode 100644 test/poll-mshot-overflow.c

diff --git a/test/Makefile b/test/Makefile
index e718583..9590e1e 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -117,6 +117,7 @@ test_srcs := \
 	poll-link.c \
 	poll-many.c \
 	poll-mshot-update.c \
+	poll-mshot-overflow.c \
 	poll-ring.c \
 	poll-v-poll.c \
 	pollfree.c \
diff --git a/test/poll-mshot-overflow.c b/test/poll-mshot-overflow.c
new file mode 100644
index 0000000..078df04
--- /dev/null
+++ b/test/poll-mshot-overflow.c
@@ -0,0 +1,128 @@
+// SPDX-License-Identifier: MIT
+
+#include <errno.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <signal.h>
+#include <poll.h>
+#include <sys/wait.h>
+
+#include "liburing.h"
+
+int check_final_cqe(struct io_uring *ring)
+{
+	struct io_uring_cqe *cqe;
+	int count = 0;
+	bool signalled_no_more = false;
+
+	while (!io_uring_peek_cqe(ring, &cqe)) {
+		if (cqe->user_data == 1) {
+			count++;
+			if (signalled_no_more) {
+				fprintf(stderr, "signalled no more!\n");
+				return 1;
+			}
+			if (!(cqe->flags & IORING_CQE_F_MORE))
+				signalled_no_more = true;
+		} else if (cqe->user_data != 3) {
+			fprintf(stderr, "%d: got unexpected %d\n", count, (int)cqe->user_data);
+			return 1;
+		}
+		io_uring_cqe_seen(ring, cqe);
+	}
+
+	if (!count) {
+		fprintf(stderr, "no cqe\n");
+		return 1;
+	}
+
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	struct io_uring_cqe *cqe;
+	struct io_uring_sqe *sqe;
+	struct io_uring ring;
+	int pipe1[2];
+	int ret, i;
+
+	if (argc > 1)
+		return 0;
+
+	if (pipe(pipe1) != 0) {
+		perror("pipe");
+		return 1;
+	}
+
+	struct io_uring_params params = {
+		.flags = IORING_SETUP_CQSIZE,
+		.cq_entries = 2
+	};
+
+	ret = io_uring_queue_init_params(2, &ring, &params);
+	if (ret) {
+		fprintf(stderr, "ring setup failed: %d\n", ret);
+		return 1;
+	}
+
+	sqe = io_uring_get_sqe(&ring);
+	if (!sqe) {
+		fprintf(stderr, "get sqe failed\n");
+		return 1;
+	}
+	io_uring_prep_poll_multishot(sqe, pipe1[0], POLLIN);
+	io_uring_sqe_set_data64(sqe, 1);
+
+	if (io_uring_cq_ready(&ring)) {
+		fprintf(stderr, "unexpected cqe\n");
+		return 1;
+	}
+
+	for (i = 0; i < 2; i++) {
+		sqe = io_uring_get_sqe(&ring);
+		io_uring_prep_nop(sqe);
+		io_uring_sqe_set_data64(sqe, 2);
+		io_uring_submit(&ring);
+	}
+
+	do {
+		errno = 0;
+		ret = write(pipe1[1], "foo", 3);
+	} while (ret == -1 && errno == EINTR);
+
+	if (ret <= 0) {
+		fprintf(stderr, "write failed: %d\n", errno);
+		return 1;
+	}
+
+	/* should have 2 cqe + 1 overflow now, so take out two cqes */
+	for (i = 0; i < 2; i++) {
+		if (io_uring_peek_cqe(&ring, &cqe)) {
+			fprintf(stderr, "unexpectedly no cqe\n");
+			return 1;
+		}
+		if (cqe->user_data != 2) {
+			fprintf(stderr, "unexpected user_data\n");
+			return 1;
+		}
+		io_uring_cqe_seen(&ring, cqe);
+	}
+
+	/* now remove the poll */
+	sqe = io_uring_get_sqe(&ring);
+	io_uring_prep_poll_remove(sqe, 1);
+	io_uring_sqe_set_data64(sqe, 3);
+	ret = io_uring_submit(&ring);
+
+	if (ret != 1) {
+		fprintf(stderr, "bad poll remove\n");
+		return 1;
+	}
+
+	ret = check_final_cqe(&ring);
+
+	return ret;
+}
-- 
2.30.2