1 /* SPDX-License-Identifier: MIT */
2 /*
3 * Test 5.7 regression with task_work not being run while a task is
4 * waiting on another event in the kernel.
5 */
6 #include <errno.h>
7 #include <poll.h>
8 #include <stdio.h>
9 #include <stdlib.h>
10 #include <sys/eventfd.h>
11 #include <unistd.h>
12 #include <pthread.h>
13 #include "liburing.h"
14 #include "helpers.h"
15
16 static int use_sqpoll = 0;
17
notify_fd(int fd)18 void notify_fd(int fd)
19 {
20 char buf[8] = {0, 0, 0, 0, 0, 0, 1};
21 int ret;
22
23 ret = write(fd, &buf, 8);
24 if (ret < 0)
25 perror("write");
26 }
27
delay_set_fd_from_thread(void * data)28 void *delay_set_fd_from_thread(void *data)
29 {
30 int fd = (intptr_t) data;
31
32 sleep(1);
33 notify_fd(fd);
34 return NULL;
35 }
36
main(int argc,char * argv[])37 int main(int argc, char *argv[])
38 {
39 struct io_uring_params p = {};
40 struct io_uring ring;
41 int loop_fd, other_fd;
42 struct io_uring_sqe *sqe;
43 struct io_uring_cqe *cqe = NULL;
44 int ret, use_fd;
45 char buf[8] = {0, 0, 0, 0, 0, 0, 1};
46 pthread_t tid;
47
48 if (argc > 1)
49 return 0;
50
51 /* Create an eventfd to be registered with the loop to be
52 * notified of events being ready
53 */
54 loop_fd = eventfd(0, EFD_CLOEXEC);
55 if (loop_fd == -1) {
56 fprintf(stderr, "eventfd errno=%d\n", errno);
57 return 1;
58 }
59
60 /* Create an eventfd that can create events */
61 use_fd = other_fd = eventfd(0, EFD_CLOEXEC);
62 if (other_fd == -1) {
63 fprintf(stderr, "eventfd errno=%d\n", errno);
64 return 1;
65 }
66
67 if (use_sqpoll)
68 p.flags = IORING_SETUP_SQPOLL;
69
70 /* Setup the ring with a registered event fd to be notified on events */
71 ret = t_create_ring_params(8, &ring, &p);
72 if (ret == T_SETUP_SKIP)
73 return 0;
74 else if (ret < 0)
75 return ret;
76
77 ret = io_uring_register_eventfd(&ring, loop_fd);
78 if (ret < 0) {
79 fprintf(stderr, "register_eventfd=%d\n", ret);
80 return 1;
81 }
82
83 if (use_sqpoll) {
84 ret = io_uring_register_files(&ring, &other_fd, 1);
85 if (ret < 0) {
86 fprintf(stderr, "register_files=%d\n", ret);
87 return 1;
88 }
89 use_fd = 0;
90 }
91
92 /* Submit a poll operation to wait on an event in other_fd */
93 sqe = io_uring_get_sqe(&ring);
94 io_uring_prep_poll_add(sqe, use_fd, POLLIN);
95 sqe->user_data = 1;
96 if (use_sqpoll)
97 sqe->flags |= IOSQE_FIXED_FILE;
98 ret = io_uring_submit(&ring);
99 if (ret != 1) {
100 fprintf(stderr, "submit=%d\n", ret);
101 return 1;
102 }
103
104 /*
105 * CASE 3: Hangs forever in Linux 5.7.5; Works in Linux 5.6.0 When this
106 * code is uncommented, we don't se a notification on other_fd until
107 * _after_ we have started the read on loop_fd. In that case, the read() on
108 * loop_fd seems to hang forever.
109 */
110 pthread_create(&tid, NULL, delay_set_fd_from_thread,
111 (void*) (intptr_t) other_fd);
112
113 /* Wait on the event fd for an event to be ready */
114 ret = read(loop_fd, buf, 8);
115 if (ret < 0) {
116 perror("read");
117 return 1;
118 } else if (ret != 8) {
119 fprintf(stderr, "Odd-sized eventfd read: %d\n", ret);
120 return 1;
121 }
122
123
124 ret = io_uring_wait_cqe(&ring, &cqe);
125 if (ret) {
126 fprintf(stderr, "wait_cqe=%d\n", ret);
127 return ret;
128 }
129 if (cqe->res < 0) {
130 fprintf(stderr, "cqe->res=%d\n", cqe->res);
131 return 1;
132 }
133
134 io_uring_cqe_seen(&ring, cqe);
135 return 0;
136 }
137