gdb/testsuite/gdb.threads/attach-slow-waitpid.c

   1 /* This testcase is part of GDB, the GNU debugger.
   2
   3    Copyright 2018-2021 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 #include <pthread.h>
  19 #include <stdio.h>
  20 #include <stdlib.h>
  21 #include <assert.h>
  22 #define NUM_THREADS 4
  23
  24 /* Crude spin lock.  Threads all spin until this is set to 0.  */
  25 int go = 1;
  26
  27 /* Thread function, just spin until GO is set to 0.  */
  28 void *
  29 perform_work (void *argument)
  30 {
  31   /* Cast to volatile to ensure that ARGUMENT is loaded each time around
  32      the loop.  */
  33   while (*((volatile int*) argument))
  34     {
  35       /* Nothing.  */
  36     }
  37   return NULL;
  38 }
  39
  40 /* The spin loop for the main thread.  */
  41 void
  42 function (void)
  43 {
  44   (void) perform_work (&go);
  45   printf ("Finished from function\n");
  46 }
  47
  48 /* Main program, create some threads which all spin waiting for GO to be
  49    set to 0.  */
  50 int
  51 main (void)
  52 {
  53   pthread_t threads[NUM_THREADS];
  54   int result_code;
  55   unsigned index;
  56
  57   /* Create some threads.  */
  58   for (index = 0; index < NUM_THREADS; ++index)
  59     {
  60       printf ("In main: creating thread %d\n", index);
  61       result_code = pthread_create (&threads[index], NULL, perform_work, &go);
  62       assert (!result_code);
  63     }
  64
  65   function ();
  66
  67   /* Wait for each thread to complete.  */
  68   for (index = 0; index < NUM_THREADS; ++index)
  69     {
  70       /* Block until thread INDEX completes.  */
  71       result_code = pthread_join (threads[index], NULL);
  72       assert (!result_code);
  73       printf ("In main: thread %d has completed\n", index);
  74     }
  75   printf ("In main: All threads completed successfully\n");
  76   return 0;
  77 }