1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (c) 2020 FUJITSU LIMITED. All rights reserved.
4 * Author: Yang Xu <[email protected]>
5 *
6 * Test Description:
7 * This case is designed to test whether pipe can wakeup all readers
8 * when last writer closes.
9 *
10 * This is also a regression test for commit 6551d5c56eb0
11 * ("pipe: make sure to wake up everybody when the last reader/writer closes").
12 * This bug was introduced by commit 0ddad21d3e99 ("pipe: use exclusive
13 * waits when reading or writing").
14 */
15 #include <unistd.h>
16 #include <sys/types.h>
17 #include <sys/wait.h>
18 #include <stdlib.h>
19 #include "tst_test.h"
20
21 static unsigned int tcases[] = {
22 2,
23 10,
24 27,
25 100
26 };
27
28 static int fds[2];
29
do_child(unsigned int i)30 static void do_child(unsigned int i)
31 {
32 char buf;
33
34 SAFE_CLOSE(fds[1]);
35 TST_CHECKPOINT_WAKE(i);
36 int ret = SAFE_READ(0, fds[0], &buf, 1);
37 if (ret != 0)
38 tst_res(TFAIL, "Wrong return from read %i", ret);
39 exit(0);
40 }
41
verify_pipe(unsigned int n)42 static void verify_pipe(unsigned int n)
43 {
44 int ret;
45 unsigned int i, cnt = 0, sleep_us = 1, fail = 0;
46 unsigned int child_num = tcases[n];
47 int pid[child_num];
48
49 SAFE_PIPE(fds);
50 tst_res(TINFO, "Creating %d child processes", child_num);
51
52 for (i = 0; i < child_num; i++) {
53 pid[i] = SAFE_FORK();
54 if (pid[i] == 0)
55 do_child(i);
56 TST_CHECKPOINT_WAIT(i);
57 TST_PROCESS_STATE_WAIT(pid[i], 'S', 0);
58 }
59
60 SAFE_CLOSE(fds[0]);
61 SAFE_CLOSE(fds[1]);
62
63 while (cnt < child_num && sleep_us < 1000000) {
64 ret = waitpid(-1, NULL, WNOHANG);
65 if (ret < 0)
66 tst_brk(TBROK | TERRNO, "waitpid()");
67 if (ret > 0) {
68 cnt++;
69 for (i = 0; i < child_num; i++) {
70 if (pid[i] == ret)
71 pid[i] = 0;
72 }
73 continue;
74 }
75 usleep(sleep_us);
76 sleep_us *= 2;
77 }
78
79 for (i = 0; i < child_num; i++) {
80 if (pid[i]) {
81 tst_res(TINFO, "pid %i still sleeps", pid[i]);
82 fail = 1;
83 SAFE_KILL(pid[i], SIGKILL);
84 SAFE_WAIT(NULL);
85 }
86 }
87
88 if (fail)
89 tst_res(TFAIL, "Closed pipe didn't wake up everyone");
90 else
91 tst_res(TPASS, "Closed pipe waked up everyone");
92 }
93
94 static struct tst_test test = {
95 .test = verify_pipe,
96 .tcnt = ARRAY_SIZE(tcases),
97 .forks_child = 1,
98 .needs_checkpoints = 1,
99 .tags = (const struct tst_tag[]) {
100 {"linux-git", "6551d5c56eb"},
101 {}
102 }
103 };
104