Quelle  dscr_default_test.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0-only
/*
 * POWER Data Stream Control Register (DSCR) default test
 *
 * This test modifies the system wide default DSCR through
 * it's sysfs interface and then verifies that all threads
 * see the correct changed DSCR value immediately.
 *
 * Copyright 2012, Anton Blanchard, IBM Corporation.
 * Copyright 2015, Anshuman Khandual, IBM Corporation.
 */

#define _GNU_SOURCE

#include "dscr.h"

#include <pthread.h>
#include <semaphore.h>
#include <unistd.h>

static void *dscr_default_lockstep_writer(void *arg)
{
 sem_t *reader_sem = (sem_t *)arg;
 sem_t *writer_sem = (sem_t *)arg + 1;
 unsigned long expected_dscr = 0;

 for (int i = 0; i < COUNT; i++) {
  FAIL_IF_EXIT(sem_wait(writer_sem));

  set_default_dscr(expected_dscr);
  expected_dscr = (expected_dscr + 1) % DSCR_MAX;

  FAIL_IF_EXIT(sem_post(reader_sem));
 }

 return NULL;
}

int dscr_default_lockstep_test(void)
{
 pthread_t writer;
 sem_t rw_semaphores[2];
 sem_t *reader_sem = &rw_semaphores[0];
 sem_t *writer_sem = &rw_semaphores[1];
 unsigned long expected_dscr = 0;

 SKIP_IF(!have_hwcap2(PPC_FEATURE2_DSCR));

 FAIL_IF(sem_init(reader_sem, 0, 0));
 FAIL_IF(sem_init(writer_sem, 0, 1));  /* writer starts first */
 FAIL_IF(bind_to_cpu(BIND_CPU_ANY) < 0);
 FAIL_IF(pthread_create(&writer, NULL, dscr_default_lockstep_writer, (void *)rw_semaphores));

 for (int i = 0; i < COUNT ; i++) {
  FAIL_IF(sem_wait(reader_sem));

  FAIL_IF(get_dscr() != expected_dscr);
  FAIL_IF(get_dscr_usr() != expected_dscr);

  expected_dscr = (expected_dscr + 1) % DSCR_MAX;

  FAIL_IF(sem_post(writer_sem));
 }

 FAIL_IF(pthread_join(writer, NULL));
 FAIL_IF(sem_destroy(reader_sem));
 FAIL_IF(sem_destroy(writer_sem));

 return 0;
}

struct random_thread_args {
 pthread_t thread_id;
 unsigned long *expected_system_dscr;
 pthread_rwlock_t *rw_lock;
 pthread_barrier_t *barrier;
};

static void *dscr_default_random_thread(void *in)
{
 struct random_thread_args *args = (struct random_thread_args *)in;
 unsigned long *expected_dscr_p = args->expected_system_dscr;
 pthread_rwlock_t *rw_lock = args->rw_lock;
 int err;

 srand(gettid());

 err = pthread_barrier_wait(args->barrier);
 FAIL_IF_EXIT(err != 0 && err != PTHREAD_BARRIER_SERIAL_THREAD);

 for (int i = 0; i < COUNT; i++) {
  unsigned long expected_dscr;
  unsigned long current_dscr;
  unsigned long current_dscr_usr;

  FAIL_IF_EXIT(pthread_rwlock_rdlock(rw_lock));
  expected_dscr = *expected_dscr_p;
  current_dscr = get_dscr();
  current_dscr_usr = get_dscr_usr();
  FAIL_IF_EXIT(pthread_rwlock_unlock(rw_lock));

  FAIL_IF_EXIT(current_dscr != expected_dscr);
  FAIL_IF_EXIT(current_dscr_usr != expected_dscr);

  if (rand() % 10 == 0) {
   unsigned long next_dscr;

   FAIL_IF_EXIT(pthread_rwlock_wrlock(rw_lock));
   next_dscr = (*expected_dscr_p + 1) % DSCR_MAX;
   set_default_dscr(next_dscr);
   *expected_dscr_p = next_dscr;
   FAIL_IF_EXIT(pthread_rwlock_unlock(rw_lock));
  }
 }

 pthread_exit((void *)0);
}

int dscr_default_random_test(void)
{
 struct random_thread_args threads[THREADS];
 unsigned long expected_system_dscr = 0;
 pthread_rwlockattr_t rwlock_attr;
 pthread_rwlock_t rw_lock;
 pthread_barrier_t barrier;

 SKIP_IF(!have_hwcap2(PPC_FEATURE2_DSCR));

 FAIL_IF(pthread_rwlockattr_setkind_np(&rwlock_attr,
           PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP));
 FAIL_IF(pthread_rwlock_init(&rw_lock, &rwlock_attr));
 FAIL_IF(pthread_barrier_init(&barrier, NULL, THREADS));

 set_default_dscr(expected_system_dscr);

 for (int i = 0; i < THREADS; i++) {
  threads[i].expected_system_dscr = &expected_system_dscr;
  threads[i].rw_lock = &rw_lock;
  threads[i].barrier = &barrier;

  FAIL_IF(pthread_create(&threads[i].thread_id, NULL,
           dscr_default_random_thread, (void *)&threads[i]));
 }

 for (int i = 0; i < THREADS; i++)
  FAIL_IF(pthread_join(threads[i].thread_id, NULL));

 FAIL_IF(pthread_barrier_destroy(&barrier));
 FAIL_IF(pthread_rwlock_destroy(&rw_lock));

 return 0;
}

int main(int argc, char *argv[])
{
 unsigned long orig_dscr_default = 0;
 int err = 0;

 if (have_hwcap2(PPC_FEATURE2_DSCR))
  orig_dscr_default = get_default_dscr();

 err |= test_harness(dscr_default_lockstep_test, "dscr_default_lockstep_test");
 err |= test_harness(dscr_default_random_test, "dscr_default_random_test");

 if (have_hwcap2(PPC_FEATURE2_DSCR))
  set_default_dscr(orig_dscr_default);

 return err;
}