Re: [PATCH V6 09/20] rtla: Add osnoise tool

+/*
+ * 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 *osnoise_cpus = tracefs_get_tracing_file("osnoise/cpus");
+	char curr_cpus[1024];
+	int retval;
+
+	context->cpus_fd = open(osnoise_cpus, O_RDWR);
+	if (!context->cpus_fd)
+		goto out_err;

+	retval = read(context->cpus_fd, &curr_cpus, sizeof(curr_cpus));
+	if (!retval)
+		goto out_close;
+	context->orig_cpus = strdup(curr_cpus);
+	if (!context->orig_cpus)
+		goto out_err;

+	retval = write(context->cpus_fd, cpus, strlen(cpus) + 1);
+	if (!retval)
+		goto out_err;

+	tracefs_put_tracing_file(osnoise_cpus);
+
+	return 0;
+
+out_close:
+	close(context->cpus_fd);
+	context->cpus_fd = -1;
+out_err:
+	tracefs_put_tracing_file(osnoise_cpus);
+	return 1;
+}
+
+/*
+ * 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;
+
+	retval = write(context->cpus_fd, context->orig_cpus, strlen(context->orig_cpus));

+	if (!retval)
+		err_msg("could not restore original osnoise cpus\n");
+
+	free(context->orig_cpus);
+}
+
+/*
+ * 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)
+{
+	char buffer[BUFF_U64_STR_SIZE];
+	char *runtime_path;
+	int retval;
+
+	if (context->runtime_us)
+		return context->runtime_us;
+
+	runtime_path = tracefs_get_tracing_file("osnoise/runtime_us");
+
+	context->runtime_fd = open(runtime_path, O_RDWR);
+	if (!context->runtime_fd)
+		goto out_err;

+	retval = read(context->runtime_fd, &buffer, sizeof(buffer));
+	if (!retval)
+		goto out_close;
+
+	context->runtime_us = get_long_from_str(buffer);
+	if (!context->runtime_us)
+		goto out_close;
+
+	context->orig_runtime_us = context->runtime_us;
+
+	tracefs_put_tracing_file(runtime_path);
+
+	return context->runtime_us;
+
+out_close:
+	close(context->runtime_fd);
+	context->runtime_fd = -1;
+out_err:
+	tracefs_put_tracing_file(runtime_path);
+	return 0;
+}
+
+/*
+ * osnoise_get_period - return the original "osnoise/period_us" value
+ *
+ * It also saves the value to be restored.
+ */
+unsigned long long osnoise_get_period(struct osnoise_context *context)
+{
+	char buffer[BUFF_U64_STR_SIZE];
+	char *period_path;
+	int retval;
+
+	if (context->period_us)
+		return context->period_us;
+
+	period_path = tracefs_get_tracing_file("osnoise/period_us");
+
+	context->period_fd = open(period_path, O_RDWR);
+	if (!context->period_fd)
+		goto out_err;

+	retval = read(context->period_fd, &buffer, sizeof(buffer));
+	if (!retval)
+		goto out_close;
+
+	context->period_us = get_long_from_str(buffer);
+	if (!context->period_us)
+		goto out_close;
+
+	context->orig_period_us = context->period_us;
+
+	tracefs_put_tracing_file(period_path);
+
+	return context->period_us;
+
+out_close:
+	close(context->period_fd);
+	context->period_fd = -1;
+out_err:
+	tracefs_put_tracing_file(period_path);
+	return 0;
+}
+
+static int __osnoise_write_runtime(struct osnoise_context *context,
+				   unsigned long long runtime)
+{
+	char buffer[BUFF_U64_STR_SIZE];
+	int retval;
+
+	if (context->runtime_fd == -1) {
+		err_msg("tried to write osnoise runtime before getting it\n");
+		return 0;
+	}
+
+	snprintf(buffer, sizeof(buffer), "%llu\n", runtime);
+
+	retval = write(context->runtime_fd, buffer, strlen(buffer) + 1);
+	if (retval < 0)
+		return -1;
+
+	context->runtime_us = runtime;
+	return 0;
+}
+
+static int __osnoise_write_period(struct osnoise_context *context,
+				  unsigned long long period)
+{
+	char buffer[BUFF_U64_STR_SIZE];
+	int retval;
+
+	if (context->period_fd == -1)
+		return 0;
+
+	snprintf(buffer, sizeof(buffer), "%llu\n", period);
+
+	retval = write(context->period_fd, buffer, strlen(buffer) + 1);
+	if (retval < 0)
+		return -1;
+
+	context->period_us = period;
+	return 0;
+}
+
+/*
+ * osnoise_set_runtime_period - set osnoise runtime and period
+ *
+ * Osnoise's runtime and period are related as runtime <= period.
+ * Thus, this function saves the original values, and then tries
+ * to set the runtime and period if they are != 0.
+ */
+int osnoise_set_runtime_period(struct osnoise_context *context,
+			       unsigned long long runtime,
+			       unsigned long long period)
+{
+	unsigned long long curr_runtime_us;
+	unsigned long long curr_period_us;
+	int retval;
+
+	if (!period && !runtime)
+		return 0;
+
+	curr_runtime_us = osnoise_get_runtime(context);
+	curr_period_us = osnoise_get_period(context);
+
+	if (!curr_period_us || !curr_runtime_us)
+		return -1;
+
+	if (!period) {
+		if (runtime > curr_period_us)
+			return -1;
+		return __osnoise_write_runtime(context, runtime);
+	} else if (!runtime) {
+		if (period < curr_runtime_us)
+			return -1;
+		return __osnoise_write_period(context, period);
+	}
+
+	if (runtime > curr_period_us) {
+		retval = __osnoise_write_period(context, period);
+		if (retval)
+			return -1;
+		retval = __osnoise_write_runtime(context, runtime);
+		if (retval)
+			return -1;
+	} else {
+		retval = __osnoise_write_runtime(context, runtime);
+		if (retval)
+			return -1;
+		retval = __osnoise_write_period(context, period);
+		if (retval)
+			return -1;
+	}
+
+	return 0;
+}
+
+/*
+ * osnoise_restore_runtime_period - restore the original runtime and period
+ */
+void osnoise_restore_runtime_period(struct osnoise_context *context)
+{
+	unsigned long long runtime = context->orig_runtime_us;
+	unsigned long long period = context->orig_period_us;
+	int retval;
+
+	if (context->runtime_fd < 0 && context->period_fd < 0)
+		return;
+
+	retval = osnoise_set_runtime_period(context, runtime, period);
+	if (retval)
+		err_msg("Could not restore original osnoise runtime/period\n");
+}
+
+/*
+ * osnoise_get_stop_us - read and save the original "stop_tracing_us"
+ */
+static long long
+osnoise_get_stop_us(struct osnoise_context *context)
+{
+	char buffer[BUFF_U64_STR_SIZE];
+	char *stop_path;
+	int retval;
+
+	if (context->stop_us_fd > 0)
+		return context->stop_us;
+
+	stop_path = tracefs_get_tracing_file("osnoise/stop_tracing_us");
+
+	context->stop_us_fd = open(stop_path, O_RDWR);
+	if (!context->stop_us_fd)
+		goto out_err;

+	retval = read(context->stop_us_fd, &buffer, sizeof(buffer));
+	if (!retval)
+		goto out_close;
+
+	context->stop_us = get_long_from_str(buffer);
+	context->orig_stop_us = context->stop_us;
+
+	tracefs_put_tracing_file(stop_path);
+
+	return context->stop_us;
+
+out_close:
+	close(context->stop_us_fd);
+	context->stop_us_fd = -1;
+out_err:
+	tracefs_put_tracing_file(stop_path);
+	return -1;
+}
+
+/*
+ * osnoise_set_stop_us - set "stop_tracing_us"
+ */
+int osnoise_set_stop_us(struct osnoise_context *context, long long stop_us)
+{
+	long long curr_stop_us = osnoise_get_stop_us(context);
+	char buffer[BUFF_U64_STR_SIZE];
+	int retval;
+
+	if (curr_stop_us < 0)
+		return -1;
+
+	snprintf(buffer, BUFF_U64_STR_SIZE, "%lld\n", stop_us);
+
+	retval = write(context->stop_us_fd, buffer, strlen(buffer) + 1);
+	if (retval < 0)
+		return -1;
+
+	context->stop_us = stop_us;
+
+	return 0;
+}
+
+/*
+ * osnoise_restore_stop_us - restore the original stop_tracing_us
+ */
+void osnoise_restore_stop_us(struct osnoise_context *context)
+{
+	char buffer[BUFF_U64_STR_SIZE];
+	int retval;
+
+	if (context->stop_us_fd < 0)
+		return;
+
+	if (context->orig_stop_us == context->stop_us)
+		return;
+
+	snprintf(buffer, BUFF_U64_STR_SIZE, "%lld\n", context->orig_stop_us);
+
+	retval = write(context->stop_us_fd, buffer, strlen(buffer) + 1);
+	if (retval < 0)
+		err_msg("Could not restore original osnoise stop_us\n");
+}
+
+/*
+ * osnoise_get_stop_us - read and save the original "stop_tracing_total_us"

+ */
+static long long
+osnoise_get_stop_total_us(struct osnoise_context *context)
+{
+	char buffer[BUFF_U64_STR_SIZE];
+	char *stop_path;
+	int retval;
+
+	if (context->stop_total_us_fd > 0)
+		return context->stop_total_us;
+
+	stop_path = tracefs_get_tracing_file("osnoise/stop_tracing_total_us");
+
+	context->stop_total_us_fd = open(stop_path, O_RDWR);
+	if (!context->stop_total_us_fd)
+		goto out_err;

+	retval = read(context->stop_total_us_fd, &buffer, sizeof(buffer));
+	if (!retval)
+		goto out_close;
+
+	context->stop_total_us = get_long_from_str(buffer);
+	context->orig_stop_total_us = context->stop_total_us;
+
+	tracefs_put_tracing_file(stop_path);
+
+	return context->stop_total_us;
+
+out_close:
+	close(context->stop_total_us_fd);
+	context->stop_total_us_fd = -1;
+out_err:
+	tracefs_put_tracing_file(stop_path);
+	return -1;
+}
+
+/*
+ * osnoise_set_stop_us - set "stop_tracing_total_us"

+ */
+int osnoise_set_stop_total_us(struct osnoise_context *context, long long stop_total_us)
+{
+	long long curr_stop_total_us = osnoise_get_stop_total_us(context);
+	char buffer[BUFF_U64_STR_SIZE];
+	int retval;
+
+	if (curr_stop_total_us < 0)
+		return -1;
+
+	snprintf(buffer, BUFF_U64_STR_SIZE, "%lld\n", stop_total_us);
+
+	retval = write(context->stop_total_us_fd, buffer, strlen(buffer) + 1);
+	if (retval < 0)
+		return -1;
+
+	context->stop_total_us = stop_total_us;
+
+	return 0;
+}
+
+/*
+ * osnoise_restore_stop_us - restore the original stop_tracing_us

+ */
+void osnoise_restore_stop_total_us(struct osnoise_context *context)
+{
+	char buffer[BUFF_U64_STR_SIZE];
+	int retval;
+
+	if (context->stop_total_us_fd < 0)
+		return;
+
+	if (context->orig_stop_total_us == context->stop_total_us)
+		return;
+
+	snprintf(buffer, BUFF_U64_STR_SIZE, "%lld\n", context->orig_stop_total_us);
+
+	retval = write(context->stop_total_us_fd, buffer, strlen(buffer) + 1);
+	if (retval < 0)
+		err_msg("Could not restore original osnoise stop_total_us\n");
+}
+
+/*
+ * osnoise_get_timerlat_period_us - read and save the original "timerlat_period_us"
+ */
+static long long
+osnoise_get_timerlat_period_us(struct osnoise_context *context)
+{
+	char buffer[BUFF_U64_STR_SIZE];
+	char *stop_path;
+	int retval;
+
+	if (context->timerlat_period_us_fd > 0)
+		return context->timerlat_period_us;
+
+	stop_path = tracefs_get_tracing_file("osnoise/timerlat_period_us");
+
+	context->timerlat_period_us_fd = open(stop_path, O_RDWR);
+	if (!context->timerlat_period_us_fd)
+		goto out_err;

+	retval = read(context->timerlat_period_us_fd, &buffer, sizeof(buffer));
+	if (!retval)
+		goto out_close;
+
+	context->timerlat_period_us = get_long_from_str(buffer);
+	context->orig_timerlat_period_us = context->timerlat_period_us;
+
+	tracefs_put_tracing_file(stop_path);
+
+	return context->timerlat_period_us;
+
+out_close:
+	close(context->timerlat_period_us_fd);
+	context->timerlat_period_us_fd = -1;
+out_err:
+	tracefs_put_tracing_file(stop_path);
+	return -1;
+}
+
+/*
+ * osnoise_set_timerlat_period_us - set "timerlat_period_us"
+ */
+int osnoise_set_timerlat_period_us(struct osnoise_context *context, long long timerlat_period_us)
+{
+	long long curr_timerlat_period_us = osnoise_get_timerlat_period_us(context);
+	char buffer[BUFF_U64_STR_SIZE];
+	int retval;
+
+	if (curr_timerlat_period_us < 0)
+		return -1;
+
+	snprintf(buffer, BUFF_U64_STR_SIZE, "%lld\n", timerlat_period_us);
+
+	retval = write(context->timerlat_period_us_fd, buffer, strlen(buffer) + 1);
+	if (retval < 0)
+		return -1;
+
+	context->timerlat_period_us = timerlat_period_us;
+
+	return 0;
+}
+
+/*
+ * osnoise_restore_timerlat_period_us - restore "timerlat_period_us"
+ */
+void osnoise_restore_timerlat_period_us(struct osnoise_context *context)
+{
+	char buffer[BUFF_U64_STR_SIZE];
+	int retval;
+
+	if (context->timerlat_period_us_fd < 0)
+		return;
+
+	if (context->orig_timerlat_period_us == context->timerlat_period_us)
+		return;
+
+	snprintf(buffer, BUFF_U64_STR_SIZE, "%lld\n", context->orig_timerlat_period_us);
+
+	retval = write(context->timerlat_period_us_fd, buffer, strlen(buffer) + 1);
+	if (retval < 0)
+		err_msg("Could not restore original osnoise timerlat_period_us\n");
+}
+
+/*
+ * osnoise_get_print_stack - read and save the original "print_stack"
+ */
+static long long
+osnoise_get_print_stack(struct osnoise_context *context)
+{
+	char buffer[BUFF_U64_STR_SIZE];
+	char *stop_path;
+	int retval;
+
+	if (context->print_stack_fd > 0)
+		return context->print_stack;
+
+	stop_path = tracefs_get_tracing_file("osnoise/print_stack");
+
+	context->print_stack_fd = open(stop_path, O_RDWR);
+	if (!context->print_stack_fd)
+		goto out_err;

+	retval = read(context->print_stack_fd, &buffer, sizeof(buffer));
+	if (!retval)
+		goto out_close;
+
+	context->print_stack = get_long_from_str(buffer);
+	context->orig_print_stack = context->print_stack;
+
+	tracefs_put_tracing_file(stop_path);
+
+	return context->print_stack;
+
+out_close:
+	close(context->print_stack_fd);
+	context->print_stack_fd = -1;
+out_err:
+	tracefs_put_tracing_file(stop_path);
+	return -1;
+}
+
+/*
+ * osnoise_set_print_stack - set "print_stack"
+ */
+int osnoise_set_print_stack(struct osnoise_context *context, long long print_stack)
+{
+	long long curr_print_stack = osnoise_get_print_stack(context);
+	char buffer[BUFF_U64_STR_SIZE];
+	int retval;
+
+	if (curr_print_stack < 0)
+		return -1;
+
+	snprintf(buffer, BUFF_U64_STR_SIZE, "%lld\n", print_stack);
+
+	retval = write(context->print_stack_fd, buffer, strlen(buffer) + 1);
+	if (retval < 0)
+		return -1;