linux-kernel - Re: [PATCH v5 1/5] counter: Internalize sysfs interface code

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Message-ID: <17c22445-d523-07f8-d1ff-59e8dbc73cc8@lechnology.com>
Date:   Wed, 14 Oct 2020 20:38:40 -0500
From:   David Lechner <david@...hnology.com>
To:     William Breathitt Gray <vilhelm.gray@...il.com>, jic23@...nel.org
Cc:     kamel.bouhara@...tlin.com, gwendal@...omium.org,
        alexandre.belloni@...tlin.com, linux-iio@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org, syednwaris@...il.com,
        patrick.havelange@...ensium.com, fabrice.gasnier@...com,
        mcoquelin.stm32@...il.com, alexandre.torgue@...com
Subject: Re: [PATCH v5 1/5] counter: Internalize sysfs interface code

On 9/26/20 9:18 PM, William Breathitt Gray wrote:
> +static ssize_t counter_comp_u8_store(struct device *dev,
> +				     struct device_attribute *attr,
> +				     const char *buf, size_t len)
> +{
> +	const struct counter_attribute *const a = to_counter_attribute(attr);
> +	struct counter_device *const counter = dev_get_drvdata(dev);
> +	struct counter_count *const count = a->parent;
> +	struct counter_synapse *const synapse = a->comp.priv;
> +	const struct counter_available *const avail = a->comp.priv;
> +	int err;
> +	bool bool_data;
> +	u8 data;
> +
> +	switch (a->comp.type) {
> +	case COUNTER_COMP_BOOL:
> +		err = kstrtobool(buf, &bool_data);
> +		data = bool_data;
> +		break;
> +	case COUNTER_COMP_FUNCTION:
> +		err = find_in_string_array(&data, count->functions_list,
> +					   count->num_functions, buf,
> +					   counter_function_str);
> +		break;
> +	case COUNTER_COMP_SYNAPSE_ACTION:
> +		err = find_in_string_array(&data, synapse->actions_list,
> +					   synapse->num_actions, buf,
> +					   counter_synapse_action_str);
> +		break;
> +	case COUNTER_COMP_ENUM:
> +		err = __sysfs_match_string(avail->strs, avail->num_items, buf);
> +		data = err;
> +		break;
> +	case COUNTER_COMP_COUNT_MODE:
> +		err = find_in_string_array(&data, avail->enums,
> +					   avail->num_items, buf,
> +					   counter_count_mode_str);
> +		break;
> +	default:
> +		err = kstrtou8(buf, 0, &data);
> +		break;
> +	}

In this function, return values are not always errors. So it would make
sense to call the err variable ret instead and check for ret < 0 below.

Setting enums to a value with index > 0 fails currently because of this.

> +	if (err)
> +		return err;
> +
> +	switch (a->scope) {
> +	case COUNTER_SCOPE_DEVICE:
> +		err = a->comp.device_u8_write(counter, data);
> +		break;
> +	case COUNTER_SCOPE_SIGNAL:
> +		err = a->comp.signal_u8_write(counter, a->parent, data);
> +		break;
> +	case COUNTER_SCOPE_COUNT:
> +		if (a->comp.type == COUNTER_COMP_SYNAPSE_ACTION)
> +			err = a->comp.action_write(counter, count, synapse,
> +						   data);
> +		else
> +			err = a->comp.count_u8_write(counter, count, data);
> +		break;
> +	}
> +	if (err)
> +		return err;
> +
> +	return len;
> +}