helgrind/tests/tc15_laog_lockdel.c

   1
   2 #include <pthread.h>
   3 #include <stdio.h>
   4 #include <stdlib.h>
   5 #include <assert.h>
   6
   7 /* Test that locks, having entered the lock acquisition tracking
   8    machinery, are forgotten by it when the client does
   9    pthread_{mutex,rwlock}_destroy.  2008-Nov-10: see comments below. */
  10
  11 int main ( void )
  12 {
  13    int r;
  14    pthread_mutex_t *mx1, *mx2;
  15    assert (sizeof(pthread_mutex_t) <= 120);
  16    mx1 = malloc(120 + sizeof(pthread_mutex_t) - sizeof(pthread_mutex_t));
  17    mx2 = malloc(120 + sizeof(pthread_mutex_t) - sizeof(pthread_mutex_t));
  18
  19    assert(mx1);
  20    assert(mx2);
  21
  22    r = pthread_mutex_init( mx1, NULL ); assert(r==0);
  23    r = pthread_mutex_init( mx2, NULL ); assert(r==0);
  24
  25    /* Establish order 1 -> 2 */
  26    fprintf(stderr, "Establish order 1 -> 2\n");
  27    r = pthread_mutex_lock( mx1 ); assert(r==0);
  28    r = pthread_mutex_lock( mx2 ); assert(r==0);
  29
  30    r = pthread_mutex_unlock( mx1 ); assert(r==0);
  31    r = pthread_mutex_unlock( mx2 ); assert(r==0);
  32
  33    /* Try order 2 -> 1.  This gives an error. */
  34    fprintf(stderr, "Try order 2 -> 1.  This gives an error.\n");
  35    r = pthread_mutex_lock( mx2 ); assert(r==0); /* error */
  36    r = pthread_mutex_lock( mx1 ); assert(r==0);
  37
  38    r = pthread_mutex_unlock( mx1 ); assert(r==0);
  39    r = pthread_mutex_unlock( mx2 ); assert(r==0);
  40
  41    /* De-initialise 2 and re-initialise it.  This gives it a new
  42       identity, so a second locking sequence 2 -> 1 should now be OK. */
  43    fprintf(stderr,
  44            "Free 2 and re-allocate it.  This gives it a new identity,\n");
  45    fprintf(stderr, "so a second locking sequence 2 -> 1 should now be OK.\n");
  46    pthread_mutex_destroy( mx2 );
  47
  48
  49
  50    r = pthread_mutex_init( mx2, NULL ); assert(r==0);
  51
  52    r = pthread_mutex_lock( mx2 ); assert(r==0);
  53    r = pthread_mutex_lock( mx1 ); assert(r==0); /* no error */
  54
  55    r = pthread_mutex_unlock( mx1 ); assert(r==0);
  56    r = pthread_mutex_unlock( mx2 ); assert(r==0);
  57
  58    /* done */
  59
  60    fprintf(stderr, "done\n");
  61    r = pthread_mutex_destroy( mx1 );
  62    r = pthread_mutex_destroy( mx2 );
  63
  64    free( mx1 );
  65    free( mx2 );
  66
  67    return 0;
  68 }
  69
  70 /* 2008-Nov-10: I believe this test is flawed and requires further
  71    investigation.  I don't think it really tests what it claims to
  72    test.  In particular, it still gives the right results if
  73    "pthread_mutex_destroy( mx2 );" at line 46 is commented out.  In
  74    other words, laog somehow forgets about mx2 so that 2->1 lock
  75    sequence at lines 52/3 does not produce a complaint, EVEN WHEN the
  76    preceding "pthread_mutex_destroy( mx2 );" is not observed.  I don't
  77    know why this is, but it seems highly suspicious to me. */