drd/tests/pth_cond_race.c

   1 /* Unit test for drd that triggers a race on the use of a POSIX condition
   2    variable. By Bart Van Assche.
   3 */
   4
   5 #include <assert.h>
   6 #include <stdio.h>      // printf()
   7 #include <pthread.h>
   8 #include <unistd.h>    // usleep()
   9
  10
  11 // Local functions declarations.
  12
  13 static void* thread_func(void* thread_arg);
  14
  15
  16 // Local variables.
  17
  18 static pthread_mutex_t s_mutex;
  19 static pthread_cond_t  s_cond;
  20 static int             s_use_mutex = 0;
  21
  22
  23 // Function definitions.
  24
  25 int main(int argc, char** argv)
  26 {
  27   int optchar;
  28   pthread_t threadid;
  29
  30   while ((optchar = getopt(argc, argv, "m")) != EOF)
  31   {
  32     switch (optchar)
  33     {
  34     case 'm':
  35       s_use_mutex = 1;
  36       break;
  37     default:
  38       assert(0);
  39     }
  40   }
  41
  42   pthread_cond_init(&s_cond, 0);
  43   pthread_mutex_init(&s_mutex, 0);
  44   pthread_mutex_lock(&s_mutex);
  45
  46   pthread_create(&threadid, 0, thread_func, 0);
  47
  48   pthread_cond_wait(&s_cond, &s_mutex);
  49   pthread_mutex_unlock(&s_mutex);
  50
  51   pthread_join(threadid, 0);
  52
  53   pthread_mutex_destroy(&s_mutex);
  54   pthread_cond_destroy(&s_cond);
  55
  56   return 0;
  57 }
  58
  59 static void* thread_func(void* thread_arg)
  60 {
  61   // Wait until the main thread has entered pthread_cond_wait().
  62   pthread_mutex_lock(&s_mutex);
  63   pthread_mutex_unlock(&s_mutex);
  64
  65   // Signal the condition variable.
  66   if (s_use_mutex) pthread_mutex_lock(&s_mutex);
  67   pthread_cond_signal(&s_cond);
  68   if (s_use_mutex) pthread_mutex_unlock(&s_mutex);
  69
  70   return 0;
  71 }