xref: /external/ltp/testcases/open_posix_testsuite/functional/threads/condvar/pthread_cond_wait_2.c

/*
 * Copyright (c) 2004, QUALCOMM Inc. All rights reserved.
 * Created by:  abisain REMOVE-THIS AT qualcomm DOT com
 * This file is licensed under the GPL license.  For the full content
 * of this license, see the COPYING file at the top level of this
 * source tree.
 *
 * Test that pthread_cond_broadcast()
 *   shall wakeup a high priority thread even when a low priority thread
 *   is running
 *
 * Steps:
 * 1. Create a condition variable
 * 2. Create a high priority thread and make it wait on the cond
 * 3. Create a low priority thread and let it busy-loop
 * 4. Both low and high prio threads run on same CPU
 * 5. Signal the cond from main and check that high priority thread
 *    got woken up and preempted low priority thread
 */

#include "affinity.h"
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <time.h>
#include "posixtest.h"
#include "safe_helpers.h"

#define TEST "5-1"
#define AREA "scheduler"
#define ERROR_PREFIX "unexpected error: " AREA " " TEST ": "

#define HIGH_PRIORITY 10
#define LOW_PRIORITY  5
#define RUNTIME       5
#define POLICY        SCHED_RR

pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t cond = PTHREAD_COND_INITIALIZER;

/* Flags that the threads use to indicate events */
static volatile int woken_up;
static volatile int low_done;

float timediff(struct timespec t2, struct timespec t1)
{
	float diff = t2.tv_sec - t1.tv_sec;
	diff += (t2.tv_nsec - t1.tv_nsec) / 1000000000.0;
	return diff;
}

void *hi_prio_thread(void *tmp)
{
	struct sched_param param;
	int policy;

	(void) tmp;
	set_affinity_single();

	SAFE_PFUNC(pthread_getschedparam(pthread_self(), &policy, &param));
	if ((policy != POLICY) || (param.sched_priority != HIGH_PRIORITY)) {
		printf("Error: the policy or priority not correct\n");
		exit(PTS_UNRESOLVED);
	}

	SAFE_PFUNC(pthread_mutex_lock(&mutex));

	/* Block, to be woken up by the signal handler */
	SAFE_PFUNC(pthread_cond_wait(&cond, &mutex));

	/* This variable is unprotected because the scheduling removes
	 * the contention
	 */
	if (!low_done)
		woken_up = 1;

	SAFE_PFUNC(pthread_mutex_unlock(&mutex));
	return NULL;
}

void *low_prio_thread(void *tmp)
{
	struct timespec start_time, current_time;
	struct sched_param param;
	int policy;

	(void) tmp;
	set_affinity_single();

	SAFE_PFUNC(pthread_getschedparam(pthread_self(), &policy, &param));
	if ((policy != POLICY) || (param.sched_priority != LOW_PRIORITY)) {
		printf("Error: the policy or priority not correct\n");
		exit(PTS_UNRESOLVED);
	}

	clock_gettime(CLOCK_REALTIME, &start_time);
	while (!woken_up) {
		clock_gettime(CLOCK_REALTIME, &current_time);
		if (timediff(current_time, start_time) > RUNTIME)
			break;
	}
	low_done = 1;
	return NULL;
}

int main()
{
	pthread_t high_id, low_id;
	pthread_attr_t high_attr;
	struct sched_param param;

	/* Create the higher priority thread */
	SAFE_PFUNC(pthread_attr_init(&high_attr));
	SAFE_PFUNC(pthread_attr_setinheritsched(&high_attr, PTHREAD_EXPLICIT_SCHED));
	SAFE_PFUNC(pthread_attr_setschedpolicy(&high_attr, POLICY));
	param.sched_priority = HIGH_PRIORITY;
	SAFE_PFUNC(pthread_attr_setschedparam(&high_attr, &param));
	SAFE_PFUNC(pthread_create(&high_id, &high_attr, hi_prio_thread, NULL));

	/* run main with same priority as low prio thread */
	param.sched_priority = LOW_PRIORITY;
	SAFE_PFUNC(pthread_setschedparam(pthread_self(), POLICY, &param));

	/* Create the low priority thread (inherits sched policy from main) */
	SAFE_PFUNC(pthread_create(&low_id, NULL, low_prio_thread, NULL));

	sleep(1);
	SAFE_PFUNC(pthread_cond_broadcast(&cond));

	/* Wait for the threads to exit */
	SAFE_PFUNC(pthread_join(low_id, NULL));
	if (!woken_up) {
		printf("Test FAILED: high priority was not woken up\n");
		exit(PTS_FAIL);
	}
	SAFE_PFUNC(pthread_join(high_id, NULL));

	printf("Test PASSED\n");
	exit(PTS_PASS);
}