gdb/testsuite/gdb.threads/access-mem-running-thread-exit.c

   1 /* This testcase is part of GDB, the GNU debugger.
   2
   3    Copyright 2021-2022 Free Software Foundation, Inc.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program 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
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  17
  18 #define _GNU_SOURCE
  19 #include <assert.h>
  20 #include <pthread.h>
  21 #include <stdlib.h>
  22 #include <stdio.h>
  23 #include <unistd.h>
  24 #include <string.h>
  25
  26 #define THREADS 20
  27
  28 static volatile unsigned int global_var = 123;
  29
  30 /* Wrapper around pthread_create.   */
  31
  32 static void
  33 create_thread (pthread_t *child,
  34                void *(*start_routine) (void *), void *arg)
  35 {
  36   int rc;
  37
  38   while ((rc = pthread_create (child, NULL, start_routine, arg)) != 0)
  39     {
  40       fprintf (stderr, "unexpected error from pthread_create: %s (%d)\n",
  41                strerror (rc), rc);
  42       sleep (1);
  43     }
  44 }
  45
  46 /* Data passed to threads on creation.  This is allocated on the heap
  47    and ownership transferred from parent to child.  */
  48
  49 struct thread_arg
  50 {
  51   /* The thread's parent.  */
  52   pthread_t parent;
  53
  54   /* Whether to call pthread_join on the parent.  */
  55   int join_parent;
  56 };
  57
  58 /* Entry point for threads.  */
  59
  60 static void *
  61 thread_fn (void *arg)
  62 {
  63   struct thread_arg *p = arg;
  64
  65   /* Passing no argument makes the thread exit immediately.  */
  66   if (p == NULL)
  67     return NULL;
  68
  69   if (p->join_parent)
  70     assert (pthread_join (p->parent, NULL) == 0);
  71
  72   /* Spawn a number of threads that exit immediately, and then join
  73      them.  The idea is to maximize the time window when we mostly
  74      have threads exiting.  */
  75   {
  76     pthread_t child[THREADS];
  77     int i;
  78
  79     /* Passing no argument makes the thread exit immediately.  */
  80     for (i = 0; i < THREADS; i++)
  81       create_thread (&child[i], thread_fn, NULL);
  82
  83     for (i = 0; i < THREADS; i++)
  84       pthread_join (child[i], NULL);
  85   }
  86
  87   /* Spawn a new thread that joins us, and exit.  The idea here is to
  88      not have any thread that stays around forever.  */
  89   {
  90     pthread_t child;
  91
  92     p->parent = pthread_self ();
  93     p->join_parent = 1;
  94     create_thread (&child, thread_fn, p);
  95   }
  96
  97   return NULL;
  98 }
  99
 100 int
 101 main (void)
 102 {
 103   int i;
 104
 105   for (i = 0; i < 4; i++)
 106     {
 107       struct thread_arg *p;
 108       pthread_t child;
 109
 110       p = malloc (sizeof *p);
 111       p->parent = pthread_self ();
 112       /* Only join the parent once.  */
 113       if (i == 0)
 114         p->join_parent = 1;
 115       else
 116         p->join_parent = 0;
 117       create_thread (&child, thread_fn, p);
 118     }
 119
 120   /* Exit the leader to make sure that we can access memory with the
 121      leader gone.  */
 122   pthread_exit (NULL);
 123 }