Add test case for circular reference SQPOLL hang

Signed-off-by: Jens Axboe <[email protected]>

.gitignore

@@ -103,6 +103,7 @@
 /test/sq-poll-dup
 /test/sq-poll-kthread
 /test/sq-poll-share
+/test/sqpoll-exit-hang
 /test/sqpoll-sleep
 /test/sq-space_left
 /test/statx

test/Makefile

@@ -99,6 +99,7 @@ test_targets += \
 	sq-poll-dup \
 	sq-poll-kthread \
 	sq-poll-share \
+	sqpoll-exit-hang \
 	sqpoll-sleep \
 	sq-space_left \
 	stdout \
@@ -224,6 +225,7 @@ test_srcs := \
 	sq-poll-dup.c \
 	sq-poll-kthread.c \
 	sq-poll-share.c \
+	sqpoll-exit-hang.c \
 	sqpoll-sleep.c \
 	sq-space_left.c \
 	statx.c \

test/sqpoll-exit-hang.c

@@ -0,0 +1,77 @@
+/*
+ * Test that we exit properly with SQPOLL and having a request that
+ * adds a circular reference to the ring itself.
+ */
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/time.h>
+#include <sys/poll.h>
+#include "liburing.h"
+
+static unsigned long long mtime_since(const struct timeval *s,
+				      const struct timeval *e)
+{
+	long long sec, usec;
+
+	sec = e->tv_sec - s->tv_sec;
+	usec = (e->tv_usec - s->tv_usec);
+	if (sec > 0 && usec < 0) {
+		sec--;
+		usec += 1000000;
+	}
+
+	sec *= 1000;
+	usec /= 1000;
+	return sec + usec;
+}
+
+static unsigned long long mtime_since_now(struct timeval *tv)
+{
+	struct timeval end;
+
+	gettimeofday(&end, NULL);
+	return mtime_since(tv, &end);
+}
+
+int main(int argc, char *argv[])
+{
+	struct io_uring_params p = {};
+	struct timeval tv;
+	struct io_uring ring;
+	struct io_uring_sqe *sqe;
+	int ret;
+
+	if (argc > 1)
+		return 0;
+
+	p.flags = IORING_SETUP_SQPOLL;
+	p.sq_thread_idle = 100;
+
+	ret = io_uring_queue_init_params(1, &ring, &p);
+	if (ret) {
+		if (geteuid()) {
+			printf("%s: skipped, not root\n", argv[0]);
+			return 0;
+		}
+		fprintf(stderr, "queue_init=%d\n", ret);
+		return 1;
+	}
+
+	if (!(p.features & IORING_FEAT_SQPOLL_NONFIXED)) {
+		fprintf(stdout, "Skipping\n");
+		return 0;
+	}
+
+	sqe = io_uring_get_sqe(&ring);
+	io_uring_prep_poll_add(sqe, ring.ring_fd, POLLIN);
+	io_uring_submit(&ring);
+
+	gettimeofday(&tv, NULL);
+	do {
+		usleep(1000);
+	} while (mtime_since_now(&tv) < 1000);
+
+	return 0;
+}