helgrind/tests/tc05_simple_race.c

   1
   2 #include <pthread.h>
   3 #include <stdio.h>
   4 #include <stdlib.h>
   5
   6 /* Simple test program, has a race.  Parent and child both modify y
   7    with no locking.  This is the program shown in Fig 2 of the
   8    original Eraser paper by Savage et al. */
   9
  10 int y = 0, v = 0;
  11 pthread_mutex_t mu = PTHREAD_MUTEX_INITIALIZER;
  12
  13 void* child_fn ( void* arg )
  14 {
  15    /* "Thread 2" in the paper */
  16    pthread_mutex_lock( &mu );
  17    v = v + 1;
  18    pthread_mutex_unlock( &mu );
  19    y = y + 1;
  20    return NULL;
  21 }
  22
  23 int main ( void )
  24 {
  25    const struct timespec delay = { 0, 100 * 1000 * 1000 };
  26    pthread_t child;
  27    if (pthread_create(&child, NULL, child_fn, NULL)) {
  28       perror("pthread_create");
  29       exit(1);
  30    }
  31    nanosleep(&delay, 0);
  32    /* "Thread 1" in the paper */
  33    y = y + 1;
  34    pthread_mutex_lock( &mu );
  35    v = v + 1;
  36    pthread_mutex_unlock( &mu );
  37
  38    if (pthread_join(child, NULL)) {
  39       perror("pthread join");
  40       exit(1);
  41    }
  42
  43    return 0;
  44 }