Add test for overflow of timeout request's sequence

Before 5da0fb1ab34c ("io_uring: consider the overflow of sequence for
timeout req"). We can meet some situation like below:

1. setup
2. prepare 4 timeout req which expected count is 1,1,2,UINT_MAX, and the
sequence of this 4 requests will be 1,2,4,2, this 4 requests will not
lead the change of cached_cq_tail and sq_dropped until the timeout
really happened. So the tail_index in io_timeout will still be 0.
3. based on the above and before this patch, the order of timeout_list
will be req1->req2->req4->req3, which the right order should be
req1->req2->req3->req4.
4. setup two nop requests. And the timeout requests will return
correctly with the patch.

Add this testcase to cover it.

Signed-off-by: yangerkun <yangerkun@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

2 files changed, 186 insertions, 2 deletions

diff --git a/test/Makefile b/test/Makefile
index 7736671..93249d4 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -8,7 +8,7 @@ all_targets += poll poll-cancel ring-leak fsync io_uring_setup io_uring_register
 		send_recvmsg a4c0b3decb33-test 500f9fbadef8-test timeout \
 		sq-space_left stdout cq-ready cq-peek-batch file-register \
 		cq-size 8a9973408177-test a0908ae19763-test 232c93d07b74-test \
-		socket-rw accept
+		socket-rw accept timeout-overflow
 
 include ../Makefile.quiet
 
@@ -23,7 +23,8 @@ test_srcs := poll.c poll-cancel.c ring-leak.c fsync.c io_uring_setup.c \
 	eeed8b54e0df-test.c link.c send_recvmsg.c a4c0b3decb33-test.c \
 	500f9fbadef8-test.c timeout.c sq-space_left.c stdout.c cq-ready.c\
 	cq-peek-batch.c file-register.c cq-size.c 8a9973408177-test.c \
-	a0908ae19763-test.c 232c93d07b74-test.c socket-rw.c accept.c
+	a0908ae19763-test.c 232c93d07b74-test.c socket-rw.c accept.c \
+	timeout-overflow.c
 
 test_objs := $(patsubst %.c,%.ol,$(test_srcs))
 
diff --git a/test/timeout-overflow.c b/test/timeout-overflow.c
new file mode 100644
index 0000000..3d34d36
--- /dev/null
+++ b/test/timeout-overflow.c
@@ -0,0 +1,183 @@
+/*
+ * Description: run timeout overflow test
+ *
+ */
+#include <errno.h>
+#include <stdio.h>
+#include <limits.h>
+#include <sys/time.h>
+
+#include "liburing.h"
+
+#define TIMEOUT_MSEC	1000
+static int not_supported;
+
+static int check_timeout_support()
+{
+	struct io_uring_sqe *sqe;
+	struct io_uring_cqe *cqe;
+	struct __kernel_timespec ts;
+	struct io_uring ring;
+	int ret;
+
+	ret = io_uring_queue_init(8, &ring, 0);
+	if (ret) {
+		printf("ring setup failed\n");
+		return 1;
+	}
+	sqe = io_uring_get_sqe(&ring);
+	ts.tv_sec = TIMEOUT_MSEC / 1000;
+	ts.tv_nsec = 0;
+	io_uring_prep_timeout(sqe, &ts, 1, 0);
+
+	ret = io_uring_submit(&ring);
+	if (ret < 0) {
+		printf("sqe submit failed: %d\n", ret);
+		goto err;
+	}
+
+	ret = io_uring_wait_cqe(&ring, &cqe);
+	if (ret < 0) {
+		printf("wait completion %d\n", ret);
+		goto err;
+	}
+
+	if (cqe->res == -EINVAL) {
+		not_supported = 1;
+		printf("Timeout not supported, ignored\n");
+		return 0;
+	}
+
+	io_uring_cqe_seen(&ring, cqe);
+	return 0;
+err:
+	return 1;
+}
+
+/*
+ * We first setup 4 timeout requests, which require a count value of 1, 1, 2,
+ * UINT_MAX, so the sequence is 1, 2, 4, 2. Before really timeout, this 4
+ * requests will not lead the change of cq_cached_tail, so as sq_dropped.
+ *
+ * And before this patch. The order of this four requests will be req1->req2->
+ * req4->req3. Actually, it should be req1->req2->req3->req4.
+ *
+ * Then, if there is 2 nop req. All timeout requests expect req4 will completed
+ * successful after the patch. And req1/req2 will completed successful with
+ * req3/req4 return -ETIME without this patch!
+ */
+static int test_timeout_overflow()
+{
+	struct io_uring_sqe *sqe;
+	struct io_uring_cqe *cqe;
+	struct __kernel_timespec ts;
+	struct io_uring ring;
+	int i, ret;
+
+	ret = io_uring_queue_init(16, &ring, 0);
+	if (ret) {
+		printf("ring setup failed\n");
+		return 1;
+	}
+
+	ts.tv_sec = TIMEOUT_MSEC / 1000;
+	ts.tv_nsec = 0;
+	for (i = 0; i < 4; i++) {
+		unsigned num;
+		sqe = io_uring_get_sqe(&ring);
+		switch (i) {
+		case 0:
+		case 1:
+			num = 1;
+			break;
+		case 2:
+			num = 2;
+			break;
+		case 3:
+			num = UINT_MAX;
+			break;
+		}
+		io_uring_prep_timeout(sqe, &ts, num, 0);
+	}
+
+	for (i = 0; i < 2; i++) {
+		sqe = io_uring_get_sqe(&ring);
+		io_uring_prep_nop(sqe);
+		io_uring_sqe_set_data(sqe, (void *) 1);
+	}
+	ret = io_uring_submit(&ring);
+	if (ret < 0) {
+		printf("sqe submit failed: %d\n", ret);
+		goto err;
+	}
+
+	i = 0;
+	while (i < 6) {
+		ret = io_uring_wait_cqe(&ring, &cqe);
+		if (ret < 0) {
+			printf("wait completion %d\n", ret);
+			goto err;
+		}
+
+		/*
+		 * cqe1: first nop req
+		 * cqe2: first timeout req, because of cqe1
+		 * cqe3: second timeout req because of cqe1 + cqe2
+		 * cqe4: second nop req
+		 * cqe5~cqe6: the left three timeout req
+		 */
+		switch (i) {
+		case 0:
+		case 3:
+			if (io_uring_cqe_get_data(cqe) != (void *) 1) {
+				printf("nop not seen as 1 or 2\n");
+				goto err;
+			}
+			break;
+		case 1:
+		case 2:
+		case 4:
+			if (cqe->res == -ETIME) {
+				printf("expected not return -ETIME for the "
+				       "%d'th timeout req\n", i - 1);
+				goto err;
+			}
+			break;
+		case 5:
+			if (cqe->res != -ETIME) {
+				printf("expected return -ETIME for the "
+				       "%d'th timeout req\n", i - 1);
+				goto err;
+			}
+			break;
+		}
+		io_uring_cqe_seen(&ring, cqe);
+		i++;
+	}
+
+	return 0;
+err:
+	return 1;
+}
+
+int main(int argc, char *argv[])
+{
+	int ret;
+
+	ret = check_timeout_support();
+	if (ret) {
+		printf("ring setup failed\n");
+		return 1;
+	}
+
+	if (not_supported)
+		return 0;
+
+	ret = test_timeout_overflow();
+	if (ret) {
+		printf("test_timeout_overflow failed\n");
+		return 1;
+	}
+
+	return 0;
+}