/*

 * Test 5.7 regression with task_work not being run while a task is

 * waiting on another event in the kernel.

 */

#include <errno.h>

#include <poll.h>

#include <stdio.h>

#include <stdlib.h>

#include <sys/eventfd.h>

#include <unistd.h>

#include <pthread.h>

#include "liburing.h"

static int use_sqpoll = 0;

void notify_fd(int fd)

{

	char buf[8] = {0, 0, 0, 0, 0, 0, 1};

	int ret;

	ret = write(fd, &buf, 8);

	if (ret < 0)

		perror("write");

}

void *delay_set_fd_from_thread(void *data)

{

	int fd = (intptr_t) data;

	sleep(1);

	notify_fd(fd);

	return NULL;

}

int main(int argc, char *argv[])

{

	struct io_uring_params p = {};

	struct io_uring ring;

	int loop_fd, other_fd;

	struct io_uring_sqe *sqe;

	struct io_uring_cqe *cqe = NULL;

	int ret, use_fd;

	char buf[8] = {0, 0, 0, 0, 0, 0, 1};

	pthread_t tid;

	if (argc > 1)

		return 0;

	/* Create an eventfd to be registered with the loop to be

	 * notified of events being ready

	 */

	loop_fd = eventfd(0, EFD_CLOEXEC);

	if (loop_fd == -1) {

		fprintf(stderr, "eventfd errno=%d\n", errno);

		return 1;

	}

	/* Create an eventfd that can create events */

	use_fd = other_fd = eventfd(0, EFD_CLOEXEC);

	if (other_fd == -1) {

		fprintf(stderr, "eventfd errno=%d\n", errno);

		return 1;

	}

	if (use_sqpoll)

		p.flags = IORING_SETUP_SQPOLL;

	/* Setup the ring with a registered event fd to be notified on events */

	ret = io_uring_queue_init_params(8, &ring, &p);

	if (ret) {

		fprintf(stderr, "queue_init=%d\n", ret);

		return 1;

	}

	ret = io_uring_register_eventfd(&ring, loop_fd);

	if (ret < 0) {

		fprintf(stderr, "register_eventfd=%d\n", ret);

		return 1;

	}

	if (use_sqpoll) {

		ret = io_uring_register_files(&ring, &other_fd, 1);

		if (ret < 0) {

			fprintf(stderr, "register_files=%d\n", ret);

			return 1;

		}

		use_fd = 0;

	}

	/* Submit a poll operation to wait on an event in other_fd */

	sqe = io_uring_get_sqe(&ring);

	io_uring_prep_poll_add(sqe, use_fd, POLLIN);

	sqe->user_data = 1;

	if (use_sqpoll)

		sqe->flags |= IOSQE_FIXED_FILE;

	ret = io_uring_submit(&ring);

	if (ret != 1) {

		fprintf(stderr, "submit=%d\n", ret);

		return 1;

	}

	/*

	 * CASE 3: Hangs forever in Linux 5.7.5; Works in Linux 5.6.0 When this

	 * code is uncommented, we don't se a notification on other_fd until

	 * _after_ we have started the read on loop_fd. In that case, the read() on

	 * loop_fd seems to hang forever.

	*/

    	pthread_create(&tid, NULL, delay_set_fd_from_thread,

			(void*) (intptr_t) other_fd);

	/* Wait on the event fd for an event to be ready */

	ret = read(loop_fd, buf, 8);

	if (ret < 0) {

		perror("read");

		return 1;

	} else if (ret != 8) {

		fprintf(stderr, "Odd-sized eventfd read: %d\n", ret);

		return 1;

	}

	ret = io_uring_wait_cqe(&ring, &cqe);

	if (ret) {

		fprintf(stderr, "wait_cqe=%d\n", ret);

		return ret;

	}

	if (cqe->res < 0) {

		fprintf(stderr, "cqe->res=%d\n", cqe->res);

		return 1;

	}

	io_uring_cqe_seen(&ring, cqe);

	return 0;

}