linux-kernel - Re: [PATCH 7/8] Input: qt2160

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Message-ID: <ZL4J4h3JJLh1UQnQ@google.com>
Date:   Sun, 23 Jul 2023 22:19:30 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Yangtao Li <frank.li@...o.com>
Cc:     linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 7/8] Input: qt2160 - convert to use devm_* api

Hi Yangtao,

On Fri, Jul 14, 2023 at 04:06:10PM +0800, Yangtao Li wrote:
> Use devm_* api to simplify code, this makes it unnecessary to explicitly
> release resources.
> 
> Signed-off-by: Yangtao Li <frank.li@...o.com>
> ---
>  drivers/input/keyboard/qt2160.c | 30 +++++++++++-------------------
>  1 file changed, 11 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/input/keyboard/qt2160.c b/drivers/input/keyboard/qt2160.c
> index 599ea85cfd30..218ef92b8c2b 100644
> --- a/drivers/input/keyboard/qt2160.c
> +++ b/drivers/input/keyboard/qt2160.c
> @@ -340,6 +340,7 @@ static bool qt2160_identify(struct i2c_client *client)
>  
>  static int qt2160_probe(struct i2c_client *client)
>  {
> +	struct device *dev = &client->dev;

You create a temporary, but half of the code does not use it. Please if
you introduce a temporary make sure everything is using it.

>  	struct qt2160_data *qt2160;
>  	struct input_dev *input;
>  	int i;
> @@ -358,12 +359,11 @@ static int qt2160_probe(struct i2c_client *client)
>  		return -ENODEV;
>  
>  	/* Chip is valid and active. Allocate structure */
> -	qt2160 = kzalloc(sizeof(struct qt2160_data), GFP_KERNEL);
> -	input = input_allocate_device();
> +	qt2160 = devm_kzalloc(dev, sizeof(struct qt2160_data), GFP_KERNEL);
> +	input = devm_input_allocate_device(dev);
>  	if (!qt2160 || !input) {

This double check was a cheat when resources did not free automatically,
it makes no sense to carry with devm.

>  		dev_err(&client->dev, "insufficient memory\n");
> -		error = -ENOMEM;
> -		goto err_free_mem;
> +		return -ENOMEM;
>  	}
>  
>  	qt2160->client = client;
> @@ -389,23 +389,23 @@ static int qt2160_probe(struct i2c_client *client)
>  	error = qt2160_write(client, QT2160_CMD_CALIBRATE, 1);
>  	if (error) {
>  		dev_err(&client->dev, "failed to calibrate device\n");
> -		goto err_free_mem;
> +		return error;
>  	}
>  
>  	if (client->irq) {
> -		error = request_irq(client->irq, qt2160_irq,
> -				    IRQF_TRIGGER_FALLING, "qt2160", qt2160);
> +		error = devm_request_irq(dev, client->irq, qt2160_irq,
> +					 IRQF_TRIGGER_FALLING, "qt2160", qt2160);
>  		if (error) {
>  			dev_err(&client->dev,
>  				"failed to allocate irq %d\n", client->irq);
> -			goto err_free_mem;
> +			return error;
>  		}
>  	}
>  
>  	error = qt2160_register_leds(qt2160);
>  	if (error) {
>  		dev_err(&client->dev, "Failed to register leds\n");
> -		goto err_free_irq;
> +		return error;
>  	}
>  
>  	error = input_register_device(qt2160->input);
> @@ -422,29 +422,21 @@ static int qt2160_probe(struct i2c_client *client)
>  
>  err_unregister_leds:
>  	qt2160_unregister_leds(qt2160);

LEDs can also be registered with devm.

> -err_free_irq:
> -	if (client->irq)
> -		free_irq(client->irq, qt2160);
> -err_free_mem:
> -	input_free_device(input);
> -	kfree(qt2160);
>  	return error;
>  }
>  
>  static void qt2160_remove(struct i2c_client *client)
>  {
>  	struct qt2160_data *qt2160 = i2c_get_clientdata(client);
> +	struct device *dev = &client->dev;
>  
>  	qt2160_unregister_leds(qt2160);
>  
>  	/* Release IRQ so no queue will be scheduled */
>  	if (client->irq)
> -		free_irq(client->irq, qt2160);
> +		devm_free_irq(dev, client->irq, qt2160);
>  
>  	cancel_delayed_work_sync(&qt2160->dwork);

It is not great that we are left with non-empty qt2160_remove(). The
driver should be converted away from using work item, and then entirety
of qt2160_remove() can be deleted.

I posted a series that cleans up the driver and incorporates an updated
version of your patch.

Thanks.

-- 
Dmitry