kernel/tools/testing/selftests/powerpc/dscr/dscr_default_test.c

   1 /*
   2  * POWER Data Stream Control Register (DSCR) default test
   3  *
   4  * This test modifies the system wide default DSCR through
   5  * it's sysfs interface and then verifies that all threads
   6  * see the correct changed DSCR value immediately.
   7  *
   8  * Copyright 2012, Anton Blanchard, IBM Corporation.
   9  * Copyright 2015, Anshuman Khandual, IBM Corporation.
  10  *
  11  * This program is free software; you can redistribute it and/or modify it
  12  * under the terms of the GNU General Public License version 2 as published
  13  * by the Free Software Foundation.
  14  */
  15 #include "dscr.h"
  16
  17 static unsigned long dscr;              /* System DSCR default */
  18 static unsigned long sequence;
  19 static unsigned long result[THREADS];
  20
  21 static void *do_test(void *in)
  22 {
  23         unsigned long thread = (unsigned long)in;
  24         unsigned long i;
  25
  26         for (i = 0; i < COUNT; i++) {
  27                 unsigned long d, cur_dscr, cur_dscr_usr;
  28                 unsigned long s1, s2;
  29
  30                 s1 = ACCESS_ONCE(sequence);
  31                 if (s1 & 1)
  32                         continue;
  33                 rmb();
  34
  35                 d = dscr;
  36                 cur_dscr = get_dscr();
  37                 cur_dscr_usr = get_dscr_usr();
  38
  39                 rmb();
  40                 s2 = sequence;
  41
  42                 if (s1 != s2)
  43                         continue;
  44
  45                 if (cur_dscr != d) {
  46                         fprintf(stderr, "thread %ld kernel DSCR should be %ld "
  47                                 "but is %ld\n", thread, d, cur_dscr);
  48                         result[thread] = 1;
  49                         pthread_exit(&result[thread]);
  50                 }
  51
  52                 if (cur_dscr_usr != d) {
  53                         fprintf(stderr, "thread %ld user DSCR should be %ld "
  54                                 "but is %ld\n", thread, d, cur_dscr_usr);
  55                         result[thread] = 1;
  56                         pthread_exit(&result[thread]);
  57                 }
  58         }
  59         result[thread] = 0;
  60         pthread_exit(&result[thread]);
  61 }
  62
  63 int dscr_default(void)
  64 {
  65         pthread_t threads[THREADS];
  66         unsigned long i, *status[THREADS];
  67         unsigned long orig_dscr_default;
  68
  69         orig_dscr_default = get_default_dscr();
  70
  71         /* Initial DSCR default */
  72         dscr = 1;
  73         set_default_dscr(dscr);
  74
  75         /* Spawn all testing threads */
  76         for (i = 0; i < THREADS; i++) {
  77                 if (pthread_create(&threads[i], NULL, do_test, (void *)i)) {
  78                         perror("pthread_create() failed");
  79                         goto fail;
  80                 }
  81         }
  82
  83         srand(getpid());
  84
  85         /* Keep changing the DSCR default */
  86         for (i = 0; i < COUNT; i++) {
  87                 double ret = uniform_deviate(rand());
  88
  89                 if (ret < 0.0001) {
  90                         sequence++;
  91                         wmb();
  92
  93                         dscr++;
  94                         if (dscr > DSCR_MAX)
  95                                 dscr = 0;
  96
  97                         set_default_dscr(dscr);
  98
  99                         wmb();
 100                         sequence++;
 101                 }
 102         }
 103
 104         /* Individual testing thread exit status */
 105         for (i = 0; i < THREADS; i++) {
 106                 if (pthread_join(threads[i], (void **)&(status[i]))) {
 107                         perror("pthread_join() failed");
 108                         goto fail;
 109                 }
 110
 111                 if (*status[i]) {
 112                         printf("%ldth thread failed to join with %ld status\n",
 113                                                                 i, *status[i]);
 114                         goto fail;
 115                 }
 116         }
 117         set_default_dscr(orig_dscr_default);
 118         return 0;
 119 fail:
 120         set_default_dscr(orig_dscr_default);
 121         return 1;
 122 }
 123
 124 int main(int argc, char *argv[])
 125 {
 126         return test_harness(dscr_default, "dscr_default_test");
 127 }