drd/tests/swapcontext.c

   1 /* See also https://bugs.kde.org/show_bug.cgi?id=432381. */
   2
   3 #define _GNU_SOURCE
   4
   5 #include <assert.h>
   6 #include <limits.h>
   7 #include <pthread.h>
   8 #include <signal.h>
   9 #include <stdlib.h>
  10 #include <string.h>
  11 #include <sys/time.h>
  12 #include <sys/timerfd.h>
  13 #include <ucontext.h>
  14 #include <unistd.h>
  15 #include "valgrind.h"
  16
  17 #define STACKSIZE (PTHREAD_STACK_MIN + 4096)
  18
  19 typedef struct thread_local {
  20   ucontext_t uc[3];
  21   size_t nrsw;
  22 } thread_local_t;
  23
  24 static void f(void *data, int n)
  25 {
  26   enum { NR_SWITCHES = 200000 };
  27   thread_local_t *tlocal = data;
  28
  29   while (1) {
  30     struct timespec delay = { .tv_nsec = 1000 };
  31     nanosleep(&delay, NULL);
  32     if (++tlocal->nrsw == NR_SWITCHES)
  33       return;
  34     swapcontext(&tlocal->uc[n], &tlocal->uc[3 - n]);
  35   }
  36 }
  37
  38 void *worker(void *data)
  39 {
  40   thread_local_t *tlocal = data;
  41
  42   if (getcontext(&(tlocal->uc[1])) < 0)
  43     abort();
  44   if (getcontext(&(tlocal->uc[2])) < 0)
  45     abort();
  46
  47   tlocal->uc[1].uc_link = &tlocal->uc[0];
  48   tlocal->uc[1].uc_stack.ss_sp = malloc(STACKSIZE);
  49   tlocal->uc[1].uc_stack.ss_size = STACKSIZE;
  50   makecontext(&tlocal->uc[1], (void (*)(void))f, 2, tlocal, 1);
  51   (void)VALGRIND_STACK_REGISTER(tlocal->uc[1].uc_stack.ss_sp,
  52                                 tlocal->uc[1].uc_stack.ss_sp +
  53                                 tlocal->uc[1].uc_stack.ss_size);
  54
  55   tlocal->uc[2].uc_link = &tlocal->uc[0];
  56   tlocal->uc[2].uc_stack.ss_sp = malloc(STACKSIZE);
  57   tlocal->uc[2].uc_stack.ss_size = STACKSIZE;
  58   makecontext(&tlocal->uc[2], (void (*)(void))f, 2, tlocal, 2);
  59   (void)VALGRIND_STACK_REGISTER(tlocal->uc[2].uc_stack.ss_sp,
  60                                 tlocal->uc[2].uc_stack.ss_sp +
  61                                 tlocal->uc[2].uc_stack.ss_size);
  62
  63   swapcontext(&tlocal->uc[0], &tlocal->uc[1]);
  64   return NULL;
  65 }
  66
  67 int main(int argc, char *argv[])
  68 {
  69   enum { NR = 32 };
  70   thread_local_t tlocal[NR];
  71   pthread_t thread[NR];
  72   pthread_attr_t attr;
  73   int i, res;
  74
  75   memset(tlocal, 0, sizeof(tlocal));
  76
  77   pthread_attr_init(&attr);
  78   res = pthread_attr_setstacksize(&attr, STACKSIZE);
  79   assert(res == 0);
  80
  81   for (i = 0; i < NR; i++)
  82     pthread_create(&thread[i], &attr, worker, &tlocal[i]);
  83
  84   pthread_attr_destroy(&attr);
  85
  86   // Wait until the threads have been created.
  87   sleep(1);
  88   for (i = 0; i < NR; i++)
  89     pthread_kill(thread[i], SIGALRM);
  90
  91   for (i = 0; i < NR; i++)
  92     pthread_join(thread[i], NULL);
  93
  94   return 0;
  95 }