malloc/tst-malloc-fork-deadlock.c

   1 /* Test concurrent fork, getline, and fflush (NULL).
   2    Copyright (C) 2016-2024 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public License as
   7    published by the Free Software Foundation; either version 2.1 of the
   8    License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If
  17    not, see <https://www.gnu.org/licenses/>.  */
  18
  19 #include <sys/wait.h>
  20 #include <unistd.h>
  21 #include <errno.h>
  22 #include <stdio.h>
  23 #include <pthread.h>
  24 #include <stdbool.h>
  25 #include <stdlib.h>
  26 #include <malloc.h>
  27 #include <time.h>
  28 #include <string.h>
  29 #include <signal.h>
  30
  31 #include <support/xthread.h>
  32 #include <support/temp_file.h>
  33 #include <support/test-driver.h>
  34
  35 enum {
  36   /* Number of threads which call fork.  */
  37   fork_thread_count = 4,
  38   /* Number of threads which call getline (and, indirectly,
  39      malloc).  */
  40   read_thread_count = 8,
  41 };
  42
  43 static bool termination_requested;
  44
  45 static void *
  46 fork_thread_function (void *closure)
  47 {
  48   while (!__atomic_load_n (&termination_requested, __ATOMIC_RELAXED))
  49     {
  50       pid_t pid = fork ();
  51       if (pid < 0)
  52         {
  53           printf ("error: fork: %m\n");
  54           abort ();
  55         }
  56       else if (pid == 0)
  57         _exit (17);
  58
  59       int status;
  60       if (waitpid (pid, &status, 0) < 0)
  61         {
  62           printf ("error: waitpid: %m\n");
  63           abort ();
  64         }
  65       if (!WIFEXITED (status) || WEXITSTATUS (status) != 17)
  66         {
  67           printf ("error: waitpid returned invalid status: %d\n", status);
  68           abort ();
  69         }
  70     }
  71   return NULL;
  72 }
  73
  74 static char *file_to_read;
  75
  76 static void *
  77 read_thread_function (void *closure)
  78 {
  79   FILE *f = fopen (file_to_read, "r");
  80   if (f == NULL)
  81     {
  82       printf ("error: fopen (%s): %m\n", file_to_read);
  83       abort ();
  84     }
  85
  86   while (!__atomic_load_n (&termination_requested, __ATOMIC_RELAXED))
  87     {
  88       rewind (f);
  89       char *line = NULL;
  90       size_t line_allocated = 0;
  91       ssize_t ret = getline (&line, &line_allocated, f);
  92       if (ret < 0)
  93         {
  94           printf ("error: getline: %m\n");
  95           abort ();
  96         }
  97       free (line);
  98     }
  99   fclose (f);
 100
 101   return NULL;
 102 }
 103
 104 static void *
 105 flushall_thread_function (void *closure)
 106 {
 107   while (!__atomic_load_n (&termination_requested, __ATOMIC_RELAXED))
 108     if (fflush (NULL) != 0)
 109       {
 110         printf ("error: fflush (NULL): %m\n");
 111         abort ();
 112       }
 113   return NULL;
 114 }
 115
 116 static void
 117 create_threads (pthread_t *threads, size_t count, void *(*func) (void *))
 118 {
 119   for (size_t i = 0; i < count; ++i)
 120     threads[i] = xpthread_create (NULL, func, NULL);
 121 }
 122
 123 static void
 124 join_threads (pthread_t *threads, size_t count)
 125 {
 126   for (size_t i = 0; i < count; ++i)
 127     xpthread_join (threads[i]);
 128 }
 129
 130 /* Create a file which consists of a single long line, and assigns
 131    file_to_read.  The hope is that this triggers an allocation in
 132    getline which needs a lock.  */
 133 static void
 134 create_file_with_large_line (void)
 135 {
 136   int fd = create_temp_file ("bug19431-large-line", &file_to_read);
 137   if (fd < 0)
 138     {
 139       printf ("error: create_temp_file: %m\n");
 140       abort ();
 141     }
 142   FILE *f = fdopen (fd, "w+");
 143   if (f == NULL)
 144     {
 145       printf ("error: fdopen: %m\n");
 146       abort ();
 147     }
 148   for (int i = 0; i < 50000; ++i)
 149     fputc ('x', f);
 150   fputc ('\n', f);
 151   if (ferror (f))
 152     {
 153       printf ("error: fputc: %m\n");
 154       abort ();
 155     }
 156   if (fclose (f) != 0)
 157     {
 158       printf ("error: fclose: %m\n");
 159       abort ();
 160     }
 161 }
 162
 163 static int
 164 do_test (void)
 165 {
 166   /* Make sure that we do not exceed the arena limit with the number
 167      of threads we configured.  */
 168   if (mallopt (M_ARENA_MAX, 400) == 0)
 169     {
 170       printf ("error: mallopt (M_ARENA_MAX) failed\n");
 171       return 1;
 172     }
 173
 174   /* Leave some room for shutting down all threads gracefully.  */
 175   int timeout = 3;
 176   if (timeout > DEFAULT_TIMEOUT)
 177     timeout = DEFAULT_TIMEOUT - 1;
 178
 179   create_file_with_large_line ();
 180
 181   pthread_t fork_threads[fork_thread_count];
 182   create_threads (fork_threads, fork_thread_count, fork_thread_function);
 183   pthread_t read_threads[read_thread_count];
 184   create_threads (read_threads, read_thread_count, read_thread_function);
 185   pthread_t flushall_threads[1];
 186   create_threads (flushall_threads, 1, flushall_thread_function);
 187
 188   struct timespec ts = {timeout, 0};
 189   if (nanosleep (&ts, NULL))
 190     {
 191       printf ("error: error: nanosleep: %m\n");
 192       abort ();
 193     }
 194
 195   __atomic_store_n (&termination_requested, true, __ATOMIC_RELAXED);
 196
 197   join_threads (flushall_threads, 1);
 198   join_threads (read_threads, read_thread_count);
 199   join_threads (fork_threads, fork_thread_count);
 200
 201   free (file_to_read);
 202
 203   return 0;
 204 }
 205
 206 #include <support/test-driver.c>