helgrind/tests/bar_trivial.c

   1
   2 /* This is the most trivial test I could think of that involves
   3    barriers.  If H fails to notice the pthread_barrier_wait call then
   4    it will report a race.  Correct behaviour is not to report a race
   5    (there isn't one.) */
   6 #define _GNU_SOURCE
   7 #include <pthread.h>
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10 #include <assert.h>
  11 #include <unistd.h>
  12
  13 int x = 0;
  14
  15 pthread_barrier_t bar;
  16
  17 void* child_fn ( void* arg )
  18 {
  19    long r, n = (long)arg;
  20
  21    if (n == 1) x++;
  22
  23    r = pthread_barrier_wait(&bar);
  24    assert(r == 0 || r == PTHREAD_BARRIER_SERIAL_THREAD);
  25
  26    if (n == 0) x++;
  27
  28    sleep(1); /* ensure both threads get to this point before
  29                 either exits. */
  30    return NULL;
  31 }
  32
  33 #define NTHR 2
  34
  35 int main ( void )
  36 {
  37    long i, r;
  38    pthread_t thr[NTHR];
  39
  40    r = pthread_barrier_init(&bar, NULL, NTHR);
  41    assert(!r);
  42
  43    for (i = 0; i < NTHR; i++) {
  44       r = pthread_create(&thr[i], NULL, child_fn, (void*)i);
  45       assert(!r);
  46    }
  47
  48    for (i = 0; i < NTHR; i++) {
  49       r = pthread_join(thr[i], NULL);
  50       assert(!r);
  51    }
  52
  53    r = pthread_barrier_destroy(&bar); assert(!r);
  54
  55    printf("x = %d\n", x);
  56    return 0;
  57 }