path: root/tools/tracing/rtla/src/osnoise.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2021 Red Hat Inc, Daniel Bristot de Oliveira <bristot@kernel.org>
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <pthread.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>

#include "osnoise.h"
#include "utils.h"

/*
 * osnoise_get_cpus - return the original "osnoise/cpus" content
 *
 * It also saves the value to be restored.
 */
char *osnoise_get_cpus(struct osnoise_context *context)
{
	if (context->curr_cpus)
		return context->curr_cpus;

	if (context->orig_cpus)
		return context->orig_cpus;

	context->orig_cpus = tracefs_instance_file_read(NULL, "osnoise/cpus", NULL);

	/*
	 * The error value (NULL) is the same for tracefs_instance_file_read()
	 * and this functions, so:
	 */
	return context->orig_cpus;
}

/*
 * osnoise_set_cpus - configure osnoise to run on *cpus
 *
 * "osnoise/cpus" file is used to set the cpus in which osnoise/timerlat
 * will run. This function opens this file, saves the current value,
 * and set the cpus passed as argument.
 */
int osnoise_set_cpus(struct osnoise_context *context, char *cpus)
{
	char *orig_cpus = osnoise_get_cpus(context);
	char buffer[1024];
	int retval;

	if (!orig_cpus)
		return -1;

	context->curr_cpus = strdup(cpus);
	if (!context->curr_cpus)
		return -1;

	snprintf(buffer, 1024, "%s\n", cpus);

	debug_msg("setting cpus to %s from %s", cpus, context->orig_cpus);

	retval = tracefs_instance_file_write(NULL, "osnoise/cpus", buffer);
	if (retval < 0) {
		free(context->curr_cpus);
		context->curr_cpus = NULL;
		return -1;
	}

	return 0;
}

/*
 * osnoise_restore_cpus - restore the original "osnoise/cpus"
 *
 * osnoise_set_cpus() saves the original data for the "osnoise/cpus"
 * file. This function restore the original config it was previously
 * modified.
 */
void osnoise_restore_cpus(struct osnoise_context *context)
{
	int retval;

	if (!context->orig_cpus)
		return;

	if (!context->curr_cpus)
		return;

	/* nothing to do? */
	if (!strcmp(context->orig_cpus, context->curr_cpus))
		goto out_done;

	debug_msg("restoring cpus to %s", context->orig_cpus);

	retval = tracefs_instance_file_write(NULL, "osnoise/cpus", context->orig_cpus);
	if (retval < 0)
		err_msg("could not restore original osnoise cpus\n");

out_done:
	free(context->curr_cpus);
	context->curr_cpus = NULL;
}

/*
 * osnoise_put_cpus - restore cpus config and cleanup data
 */
void osnoise_put_cpus(struct osnoise_context *context)
{
	osnoise_restore_cpus(context);

	if (!context->orig_cpus)
		return;

	free(context->orig_cpus);
	context->orig_cpus = NULL;
}

/*
 * osnoise_read_ll_config - read a long long value from a config
 *
 * returns -1 on error.
 */
static long long osnoise_read_ll_config(char *rel_path)
{
	long long retval;
	char *buffer;

	buffer = tracefs_instance_file_read(NULL, rel_path, NULL);
	if (!buffer)
		return -1;

	/* get_llong_from_str returns -1 on error */
	retval = get_llong_from_str(buffer);

	debug_msg("reading %s returned %lld\n", rel_path, retval);

	free(buffer);

	return retval;
}

/*
 * osnoise_write_ll_config - write a long long value to a config in rel_path
 *
 * returns -1 on error.
 */
static long long osnoise_write_ll_config(char *rel_path, long long value)
{
	char buffer[BUFF_U64_STR_SIZE];
	long long retval;

	snprintf(buffer, sizeof(buffer), "%lld\n", value);

	debug_msg("setting %s to %lld\n", rel_path, value);

	retval = tracefs_instance_file_write(NULL, rel_path, buffer);
	return retval;
}

/*
 * osnoise_get_runtime - return the original "osnoise/runtime_us" value
 *
 * It also saves the value to be restored.
 */
unsigned long long osnoise_get_runtime(struct osnoise_context *context)
{
	long long runtime_us;

	if (context->runtime_us != OSNOISE_TIME_INIT_VAL)
		return context->runtime_us;

	if (context->orig_runtime_us != OSNOISE_TIME_INIT_VAL)
		return context->orig_runtime_us;

	runtime_us = osnoise_read_ll_config("osnoise/runtime_us");
	if (runtime_us < 0)
		goto out_err;

	context->orig_runtime_us