memcheck/tests/reach_thread_register.c

   1 #define _GNU_SOURCE
   2
   3 #include <pthread.h>
   4 #include <sched.h>
   5 #include <stdio.h>
   6 #include <stdlib.h>
   7 #include <unistd.h>
   8 #include <config.h>
   9
  10 /* test based on code from Jeffrey Yasskin, slightly modified. */
  11 /* Reproduces a false positive leak when a pointer is (only) in a live
  12    thread register, and another thread calls exit */
  13
  14 pthread_mutex_t mu = PTHREAD_MUTEX_INITIALIZER;
  15 int cont = 1;
  16
  17 void* helper(void* v_bar) {
  18   pthread_barrier_t* bar = (pthread_barrier_t*)v_bar;
  19   register int* i = malloc(sizeof(*i));
  20   // Try hard to have i allocated in a register.
  21   *i = 3;
  22   pthread_barrier_wait(bar);
  23   pthread_mutex_lock(&mu);
  24   while (cont) {
  25 #if defined(VGA_x86) || defined(VGA_amd64)
  26      // Below helps to have i really in a register.
  27      asm volatile("test %0, %0" : : "S"(i));
  28 #else
  29      // Not clear that for other archs, i is in a register.
  30      if (*i) // should do better for other archs.
  31         // "then" part after the #endif
  32 #endif
  33      pthread_mutex_unlock(&mu);
  34      sched_yield();
  35      pthread_mutex_lock(&mu);
  36   }
  37   pthread_mutex_unlock(&mu);
  38   free((void *)i);
  39   fprintf(stderr, "Quitting the helper.\n");
  40   return NULL;
  41 }
  42
  43 int main() {
  44   pthread_barrier_t bar;
  45   pthread_barrier_init(&bar, NULL, 2);
  46   pthread_t thr;
  47   pthread_create(&thr, NULL, &helper, &bar);
  48   pthread_barrier_wait(&bar);
  49   pthread_barrier_destroy(&bar);
  50   fprintf(stderr, "Abandoning the helper.\n");
  51   pthread_detach(thr);
  52   return 0;
  53 }