test/insanesync.c

   1 #include <stdlib.h>
   2 #include <stdio.h>
   3 #include <threads.h>
   4 #include <stdatomic.h>
   5
   6 #include "librace.h"
   7 #include "model-assert.h"
   8
   9 atomic_int x;
  10 atomic_int y;
  11 atomic_intptr_t z;
  12 atomic_intptr_t z2;
  13
  14 /**
  15                 This example illustrates a self-satisfying cycle involving
  16                 synchronization.  A failed synchronization creates the store that
  17                 causes the synchronization to fail.
  18
  19                 The C++11 memory model nominally allows t1=0, t2=1, t3=5.
  20
  21                 This example is insane, we don't support that behavior.
  22 */
  23
  24
  25 static void a(void *obj)
  26 {
  27         atomic_store_explicit(&z, (intptr_t) &y, memory_order_relaxed);
  28         int t1=atomic_fetch_add_explicit(&y, 1, memory_order_release);
  29         atomic_store_explicit(&z, (intptr_t) &x, memory_order_relaxed);
  30         int t2=atomic_fetch_add_explicit(&y, 1, memory_order_release);
  31         printf("t1=%d, t2=%d\n", t1, t2);
  32 }
  33
  34
  35 static void b(void *obj)
  36 {
  37         int t3=atomic_fetch_add_explicit(&y, 1, memory_order_acquire);
  38         void *ptr = (void *)atomic_load_explicit(&z, memory_order_relaxed);
  39         atomic_store_explicit(&z2, (intptr_t)ptr, memory_order_relaxed);
  40         printf("t3=%d\n", t3);
  41 }
  42
  43 static void c(void *obj)
  44 {
  45         void * ptr2=(void *) atomic_load_explicit(&z2, memory_order_relaxed);
  46         atomic_store_explicit((atomic_int *)ptr2, 5, memory_order_relaxed);
  47 }
  48
  49 int user_main(int argc, char **argv)
  50 {
  51         thrd_t t1, t2, t3;
  52
  53
  54         atomic_init(&x, 0);
  55         atomic_init(&y, 0);
  56         atomic_init(&z, (intptr_t) &x);
  57         atomic_init(&z2, (intptr_t) &x);
  58
  59         thrd_create(&t1, (thrd_start_t)&a, NULL);
  60         thrd_create(&t2, (thrd_start_t)&b, NULL);
  61         thrd_create(&t3, (thrd_start_t)&c, NULL);
  62
  63         thrd_join(t1);
  64         thrd_join(t2);
  65         thrd_join(t3);
  66
  67
  68         return 0;
  69 }