drd/tests/fp_race.c

   1 /* Test data race detection between floating point variables. */
   2
   3
   4 #include <assert.h>
   5 #include <stdio.h>     /* printf() */
   6 #include <pthread.h>
   7 #include <unistd.h>    /* sleep() */
   8
   9
  10 /* Local functions declarations. */
  11
  12 static void* thread_func(void*);
  13
  14
  15 /* Local variables. */
  16
  17 /* s_mutex protects s_d3. */
  18 static pthread_mutex_t s_mutex;
  19
  20 static double s_d1; /* accessed before thread creation and in the created */
  21                     /* thread (not a race). */
  22 static double s_d2; /* accessed in the created thread and after the join */
  23                     /* (not a race). */
  24 static double s_d3; /* accessed simultaneously from both threads (race). */
  25 static int    s_debug     = 0;
  26 static int    s_do_printf = 0;
  27 static int    s_use_mutex = 0;
  28
  29
  30 /* Function definitions. */
  31
  32 int main(int argc, char** argv)
  33 {
  34   int optchar;
  35   pthread_t threadid;
  36
  37   while ((optchar = getopt(argc, argv, "dmp")) != EOF)
  38   {
  39     switch (optchar)
  40     {
  41     case 'd':
  42       s_debug = 1;
  43       break;
  44     case 'm':
  45       s_use_mutex = 1;
  46       break;
  47     case 'p':
  48       s_do_printf = 1;
  49       break;
  50     default:
  51       assert(0);
  52     }
  53   }
  54
  55   pthread_mutex_init(&s_mutex, 0);
  56
  57   /*
  58    * Switch to line-buffered mode, such that timing information can be
  59    * obtained for each printf() call with strace.
  60    */
  61   setlinebuf(stdout);
  62
  63   if (s_debug)
  64   {
  65     printf("&s_d1 = %p; &s_d2 = %p; &s_d3 = %p\n", &s_d1, &s_d2, &s_d3);
  66   }
  67
  68   s_d1 = 1;
  69   s_d3 = 3;
  70
  71   pthread_create(&threadid, 0, thread_func, 0);
  72
  73   sleep(1); /* Wait until thread_func() finished. */
  74
  75   {
  76     if (s_use_mutex) pthread_mutex_lock(&s_mutex);
  77     s_d3++;
  78     if (s_use_mutex) pthread_mutex_unlock(&s_mutex);
  79   }
  80
  81   /* Wait until the thread finished. */
  82   pthread_join(threadid, 0);
  83   if (s_do_printf) printf("s_d2 = %g (should be 2)\n", s_d2);
  84   if (s_do_printf) printf("s_d3 = %g (should be 5)\n", s_d3);
  85
  86   pthread_mutex_destroy(&s_mutex);
  87
  88   return 0;
  89 }
  90
  91 static void* thread_func(void* thread_arg)
  92 {
  93   if (s_do_printf)
  94   {
  95     printf("s_d1 = %g (should be 1)\n", s_d1);
  96   }
  97   s_d2 = 2;
  98   {
  99     if (s_use_mutex) pthread_mutex_lock(&s_mutex);
 100     s_d3++;
 101     if (s_use_mutex) pthread_mutex_unlock(&s_mutex);
 102   }
 103   return 0;
 104 }