1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (C) 2023 SUSE LLC Andrea Cervesato <andrea.cervesato@suse.com>
4 */
5
6 /*\
7 * [Description]
8 *
9 * Verify that edge triggering is correctly handled by epoll, for both EPOLLIN
10 * and EPOLLOUT.
11 *
12 * [Algorithm]
13 *
14 * - The file descriptors for non-blocking pipe are registered on an epoll
15 * instance.
16 * - A pipe writer writes data on the write side of the pipe.
17 * - A call to epoll_wait() is done that will return a EPOLLIN event.
18 * - The pipe reader reads half of data from rfd.
19 * - A call to epoll_wait() should hang because there's data left to read.
20 * - The pipe reader reads remaining data from rfd.
21 * - A call to epoll_wait() should return a EPOLLOUT event.
22 */
23
24 #define _GNU_SOURCE
25
26 #include <fcntl.h>
27 #include "tst_test.h"
28 #include "tst_epoll.h"
29
30 static size_t write_size;
31 static size_t read_size;
32 static int fds[2];
33 static int epfd;
34
setup(void)35 static void setup(void)
36 {
37 write_size = getpagesize();
38 read_size = write_size / 2;
39
40 SAFE_PIPE2(fds, O_NONBLOCK);
41
42 /* EPOLLOUT will be raised when buffer became empty after becoming full */
43 SAFE_FCNTL(fds[1], F_SETPIPE_SZ, write_size);
44 }
45
cleanup(void)46 static void cleanup(void)
47 {
48 if (epfd > 0)
49 SAFE_CLOSE(epfd);
50
51 if (fds[0] > 0)
52 SAFE_CLOSE(fds[0]);
53
54 if (fds[1] > 0)
55 SAFE_CLOSE(fds[1]);
56 }
57
run(void)58 static void run(void)
59 {
60 char buff[write_size];
61 struct epoll_event evt_receive;
62
63 tst_res(TINFO, "Polling on channel with EPOLLET");
64
65 epfd = SAFE_EPOLL_CREATE1(0);
66
67 SAFE_EPOLL_CTL(epfd, EPOLL_CTL_ADD, fds[0], &((struct epoll_event) {
68 .events = EPOLLIN | EPOLLET,
69 .data.fd = fds[0],
70 }));
71 SAFE_EPOLL_CTL(epfd, EPOLL_CTL_ADD, fds[1], &((struct epoll_event) {
72 .events = EPOLLOUT | EPOLLET,
73 .data.fd = fds[1],
74 }));
75
76 tst_res(TINFO, "Write bytes on channel: %zu bytes", write_size);
77
78 memset(buff, 'a', write_size);
79 SAFE_WRITE(SAFE_WRITE_ANY, fds[1], buff, write_size);
80 TST_EXP_FAIL(write(fds[1], buff, write_size), EAGAIN, "write() failed");
81
82 TST_EXP_EQ_LI(SAFE_EPOLL_WAIT(epfd, &evt_receive, 1, 0), 1);
83 TST_EXP_EQ_LI(evt_receive.data.fd, fds[0]);
84 TST_EXP_EQ_LI(evt_receive.events & EPOLLIN, EPOLLIN);
85
86 tst_res(TINFO, "Read half bytes from channel: %zu bytes", read_size);
87
88 memset(buff, 0, write_size);
89 SAFE_READ(1, fds[0], buff, read_size);
90
91 TST_EXP_EQ_LI(SAFE_EPOLL_WAIT(epfd, &evt_receive, 1, 0), 0);
92
93 tst_res(TINFO, "Read remaining bytes from channel: %zu bytes", read_size);
94
95 SAFE_READ(1, fds[0], buff + read_size, read_size);
96 TST_EXP_FAIL(read(fds[0], buff, read_size), EAGAIN, "read() failed");
97
98 TST_EXP_EQ_LI(SAFE_EPOLL_WAIT(epfd, &evt_receive, 1, 0), 1);
99 TST_EXP_EQ_LI(evt_receive.data.fd, fds[1]);
100 TST_EXP_EQ_LI(evt_receive.events & EPOLLOUT, EPOLLOUT);
101 }
102
103 static struct tst_test test = {
104 .setup = setup,
105 .cleanup = cleanup,
106 .test_all = run,
107 };
108