1 // SPDX-License-Identifier: GPL-2.0
2 
3 #define _GNU_SOURCE
4 #include <errno.h>
5 #include <linux/types.h>
6 #include <poll.h>
7 #include <signal.h>
8 #include <stdbool.h>
9 #include <stdio.h>
10 #include <stdlib.h>
11 #include <string.h>
12 #include <syscall.h>
13 #include <sys/wait.h>
14 #include <unistd.h>
15 
16 #include "pidfd.h"
17 #include "../kselftest.h"
18 
19 static bool timeout;
20 
handle_alarm(int sig)21 static void handle_alarm(int sig)
22 {
23 	timeout = true;
24 }
25 
main(int argc,char ** argv)26 int main(int argc, char **argv)
27 {
28 	struct pollfd fds;
29 	int iter, nevents;
30 	int nr_iterations = 10000;
31 
32 	fds.events = POLLIN;
33 
34 	if (argc > 2)
35 		ksft_exit_fail_msg("Unexpected command line argument\n");
36 
37 	if (argc == 2) {
38 		nr_iterations = atoi(argv[1]);
39 		if (nr_iterations <= 0)
40 			ksft_exit_fail_msg("invalid input parameter %s\n",
41 					argv[1]);
42 	}
43 
44 	ksft_print_msg("running pidfd poll test for %d iterations\n",
45 		nr_iterations);
46 
47 	for (iter = 0; iter < nr_iterations; iter++) {
48 		int pidfd;
49 		int child_pid = fork();
50 
51 		if (child_pid < 0) {
52 			if (errno == EAGAIN) {
53 				iter--;
54 				continue;
55 			}
56 			ksft_exit_fail_msg(
57 				"%s - failed to fork a child process\n",
58 				strerror(errno));
59 		}
60 
61 		if (child_pid == 0) {
62 			/* Child process just sleeps for a min and exits */
63 			sleep(60);
64 			exit(EXIT_SUCCESS);
65 		}
66 
67 		/* Parent kills the child and waits for its death */
68 		pidfd = sys_pidfd_open(child_pid, 0);
69 		if (pidfd < 0)
70 			ksft_exit_fail_msg("%s - pidfd_open failed\n",
71 					strerror(errno));
72 
73 		/* Setup 3 sec alarm - plenty of time */
74 		if (signal(SIGALRM, handle_alarm) == SIG_ERR)
75 			ksft_exit_fail_msg("%s - signal failed\n",
76 					strerror(errno));
77 		alarm(3);
78 
79 		/* Send SIGKILL to the child */
80 		if (sys_pidfd_send_signal(pidfd, SIGKILL, NULL, 0))
81 			ksft_exit_fail_msg("%s - pidfd_send_signal failed\n",
82 					strerror(errno));
83 
84 		/* Wait for the death notification */
85 		fds.fd = pidfd;
86 		nevents = poll(&fds, 1, -1);
87 
88 		/* Check for error conditions */
89 		if (nevents < 0)
90 			ksft_exit_fail_msg("%s - poll failed\n",
91 					strerror(errno));
92 
93 		if (nevents != 1)
94 			ksft_exit_fail_msg("unexpected poll result: %d\n",
95 					nevents);
96 
97 		if (!(fds.revents & POLLIN))
98 			ksft_exit_fail_msg(
99 				"unexpected event type received: 0x%x\n",
100 				fds.revents);
101 
102 		if (timeout)
103 			ksft_exit_fail_msg(
104 				"death notification wait timeout\n");
105 
106 		close(pidfd);
107 		/* Wait for child to prevent zombies */
108 		if (waitpid(child_pid, NULL, 0) < 0)
109 			ksft_exit_fail_msg("%s - waitpid failed\n",
110 					strerror(errno));
111 
112 	}
113 
114 	ksft_test_result_pass("pidfd poll test: pass\n");
115 	return ksft_exit_pass();
116 }
117