linux-kernel - Re: [PATCH] mfd: avoid two assignments if failures happen in tps65910_i2c

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Date:	Fri, 15 Jul 2011 10:12:26 +0100
From:	Graeme Gregory <gg@...mlogic.co.uk>
To:	Jesper Juhl <jj@...osbits.net>
CC:	Samuel Ortiz <sameo@...ux.intel.com>, linux-kernel@...r.kernel.org,
	Jorge Eduardo Candelaria <jedu@...mlogic.co.uk>
Subject: Re: [PATCH] mfd: avoid two assignments if failures happen in tps65910_i2c_probe

On 07/13/2011 10:22 PM, Jesper Juhl wrote:
> In drivers/mfd/tps65910.c:tps65910_i2c_probe() there's potential for a
> tiny optimization.
>
> We assign to init_data->irq and init_data->irq_base long before we
> need them, and there are two potential exits from the function before
> they are needed.
>
> Moving the assignments below these two potential exits means we
> completely avoid doing them in these two (failure) cases.
>
> Signed-off-by: Jesper Juhl <jj@...osbits.net>
> ---
>  drivers/mfd/tps65910.c |    6 +++---
>  1 files changed, 3 insertions(+), 3 deletions(-)
>
>   - compile tested only.
>   - patch is on top of the patch in https://lkml.org/lkml/2011/7/5/503 
>     which is now in linux-next.
>
> diff --git a/drivers/mfd/tps65910.c b/drivers/mfd/tps65910.c
> index 7a3eb2d..65e9479 100644
> --- a/drivers/mfd/tps65910.c
> +++ b/drivers/mfd/tps65910.c
> @@ -147,9 +147,6 @@ static int tps65910_i2c_probe(struct i2c_client *i2c,
>  	if (init_data == NULL)
>  		return -ENOMEM;
>  
> -	init_data->irq = pmic_plat_data->irq;
> -	init_data->irq_base = pmic_plat_data->irq;
> -
>  	tps65910 = kzalloc(sizeof(struct tps65910), GFP_KERNEL);
>  	if (tps65910 == NULL) {
>  		kfree(init_data);
> @@ -170,6 +167,9 @@ static int tps65910_i2c_probe(struct i2c_client *i2c,
>  	if (ret < 0)
>  		goto err;
>  
> +	init_data->irq = pmic_plat_data->irq;
> +	init_data->irq_base = pmic_plat_data->irq;
> +
>  	tps65910_gpio_init(tps65910, pmic_plat_data->gpio_base);
>  
>  	ret = tps65910_irq_init(tps65910, init_data->irq, init_data);
Not sure this form of micro optimisation really buys anything, but the
resulting code does look nicer so.

Acked-by: Graeme Gregory <gg@...mlogic.co.uk>

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