tools/testing/selftests/pidfd/pidfd_poll_test.c

   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
  21 static void handle_alarm(int sig)
  22 {
  23         timeout = true;
  24 }
  25
  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 }